Browse Topic: Ignition systems

Items (2,854)

A Numerical Study on the Effect of a Pre-Chamber Initiated Turbulent Jet on Main Chamber Combustion

2022-01-0469

3/29/2022

To elucidate the complex characteristics of pre-chamber combustion engines, the interaction of the hot gas jets initiated by an active narrow throated pre-chamber with lean premixed CH4/air in a heavy-duty engine was studied computationally. A twelve-hole KAUST proprietary pre-chamber geometry was investigated using CONVERGE software. The KAUST pre-chamber has an upper conical part with the spark plug, and fuel injector, followed by a straight narrow region called the throat and nozzles connecting the chambers. The simulations were run for an entire cycle, starting at the previous cycle's exhaust valve opening (EVO). The SAGE combustion model was used with the chemistry modeled using a reduced methane oxidation mechanism based on GRI Mech 3.0, which was validated against in-house OH chemiluminescence data from the optical engine experiments. Two different piston geometries, a flat piston geometry, and a more realistic bowl piston geometry were studied to understand the influence of jet on main chamber combustion. Varying the piston geometries results in different free jet times and hence main chamber combustion characteristics. Pre-chamber fuel ratio (PCFR) 6% of the total amount of fuel was investigated while keeping the global excess air ratios (λ) condition a constant value of 2.0. Both piston cases resulted in similar pre-chamber pressurization, with almost the same pre-chamber discharge and the equal pressure difference between pre-and main-chamber (ΔP) at the start of jet ejection. Different combustion behaviors were observed on analysis of the heat release rate in the main chamber. The importance of turbulence generated by the pre-chamber-initiated jets was further studied. It was observed that free jet time is a critical factor in developing turbulence in the main chamber. This increase in turbulence helps in increasing the burning velocity causing faster combustion. The influence of the jet-piston interaction is also analyzed as that determines the combustion behavior in the later CAD.

Sanal, Sangeeth, Echeverri Marquez, Manuel, Silva, Mickael, Cenker, Emre, Im, Hong G.

021 - Development of a 0D Model Starting from Different RANS CFD Tumble Flow Fields in Order to Predict the Turbulence Evolution at Ignition Timing

SAE-PP-001501/25/2021

aster combustion and lower cycle-to-cycle variability are mandatory tasks for naturally aspirated engines to reduce emission levels and to increase engine efficiency. The promotion of a stable and coherent tumble structure is considered as one of the best way to promote the in-cylinder turbulence and therefore the combustion velocity. During the compression stroke the tumble vortex is deformed, accelerated and its breakdown in smaller eddies leads to the turbulence enhancement process. The prediction of the final level of turbulence for a particular engine operating point is crucial during the engine design process because it represents a practical comparative means for different engine solutions. The tumble ratio parameter value represents a first step toward the evaluation of the turbulence level at ignition time, but it has an intrinsic limit. The tumble ratio parameter represents the value of the angular velocity of a single macro vortex, while the flow-field is often characterized by multiple vortexes, sometimes some rotating and some counter-rotating. The idea at the basis of the paper is: To develop a quasi-predictive 0D model for defining the final mean level of the turbulence at the ignition time. The model is fed by the curtain intake valve mass flow rate and the intake valve lift trend. In order to validate the 0D model the results were compared versus 3D CFD results. To extract from a 3D CFD flow field at IVC the type and the number of the vortexes. The 3D CFD RANS simulations were performed by AVL Fire code v. 2010. To demonstrate through some 3D CFD results that the flow field structure was a function only of the engine type and the load condition. Finally the flow field structure could be used in the 0D model on varying the engine speeds as a means of improvement of the model prediction capability.

Mutagaana, Festo

Automatic Pilots (Turbine Powered Subsonic Aircraft)

AS440B (Current)

12/22/2020

This SAE Aerospace Standard (AS) covers automatic pilots intended for use on aircraft to automatically operate the primary and trim aerodynamic controls to maintain stable flight and/or to provide maneuvering about any of the three axes through servo control. Automatic control functions essential for primary or augmented flight control are excluded.

A-4 Aircraft Instruments Committee

Ignition System Measurements Procedure

J973_202011 (Historical)

11/3/2020

This SAE Recommended Practice specifies the design and/or evaluation with the specific equipment, conditions, and methods for distributorless battery ignition systems intended for use in various internal combustion engines including automotive, marine, motorcycle, and utility engine applications. The test procedures listed in this document are limited to measurements performed on a test bench only and do not include measurements made directly on engines or vehicles. This standard is not intended to supply information for battery ignition systems used in aircraft applications of any type.

Ignition Standards Committee

Lubricating Oil, Aircraft Piston Engine (Ashless Dispersant)

J1899_202010 (Current)

10/28/2020

This SAE Standard establishes the requirements for lubricating oils containing ashless dispersant additives to be used in four-stroke cycle, reciprocating piston aircraft engines. This document covers the same lubricating oil requirements as the former military specification MIL-L-22851. Users should consult their airframe or engine manufacturers manuals for the latest listing of acceptable lubricants.

E-38 Aviation Piston Engine Fuels and Lubricants

Silicone Compound, NATO Code Number S-736

AS8660A (Current)9/14/2020

This specification covers one type of a nonmelting, heat stable silicone compound for use in high tension electrical connections, ignition systems and electronics equipment; for application to unpainted mating threaded or non-threaded surfaces, and as a lubricant for components fabricated from rubber. This compound is effective in the temperature range from -54°C (-65°F) to +204°C (+400°F) for extended periods and to 260°C (500°F) for short periods. This compound is identified by NATO symbol S-736 (see 6.5).

AMS M Aerospace Greases Committee

Tools, Inserting and Extracting Helical Coil Wire Screw Thread Inserts Inch and Spark Plug Sizes

AS59158A (Current)

8/3/2020

This SAE Aerospace Standard (AS) describes taps, thread plug gages, inserting tools, expanding tools, offset and staking tools, tang break-off tools, extracting tools and thread repair kits.

EG-1B Hand Tools Committee

Preignition Rating of Spark Plugs

J549_202006 (Current)

6/15/2020

This SAE Recommended Practice describes the equipment and procedures used in obtaining preignition ratings of spark plugs.

Ignition Standards Committee

Knock, Auto-Ignition and Pre-Ignition Tendency of Fuels for Advanced Combustion Engines (FACE) with Ethanol Blends and Similar RON

2020-01-06134/14/2020

Researchers have known about a higher pre-ignition frequency of alcohol fuels for several decades now. Several studies, assessing the effect of ethanol addition on stochastic pre-ignition, have shown contradicting observations. Researchers at FEV observed an increase in pre-ignition frequency with an increase in ethanol concentration, however the pre-ignition events at high ethanol content did not lead to super-knock. Most of the studies have used varying ethanol fraction in a common base-fuel, thereby varying the auto-ignition tendency of the blend. In the current study, the effect of ethanol addition on FACE (Fuels for Advanced Combustion Engines) gasolines is assessed. Five different FACE gasolines (FACE A, C, I, J and G) were used for the study. Ignition delay time of varying ethanol fractions in FACE gasolines was measured in an Ignition Quality Tester (IQT), following ASTM 6890. The measurements showed that 13% ethanol (v/v) is needed for FACE A and C, while 27% ethanol (v/v) is needed for FACE I and J to match the ignition delay time of FACE G fuel. The five blends were tested in a Co-operative Fuel Research (CFR) engine in Homogeneous Charge Compression Ignition (HCCI) and Spark Ignition (SI) combustion mode. The experiments showed similar auto-ignition and knocking tendency for the five blends. After that, the pre-ignition tendency of the blends was assessed in a supercharged AVL engine. In general, increasing ethanol content led to higher pre-ignition frequency. Moreover, the effect of ethanol on increasing pre-ignition frequency was dependent on the base-fuel into which ethanol was added. For the same ethanol fraction added, base-fuels with higher aromatic content showed higher pre-ignition frequency.

Singh, Eshan, Dibble, Robert

Characteristics of Auto-Ignition for Lubricants and Lubricant/Gasoline Based on an Innovative Single Droplet Test System

2020-01-14284/14/2020

Due to the advantages of low weight, low emissions and good fuel economy, downsized turbocharged gasoline direct injection (GDI) engines are widely-applied nowadays. However, Low-Speed Pre-Ignition (LSPI) phenomenon observed in these engines restricts their improvement of performance. Some researchers have shown that auto-ignition of lubricant in the combustion chamber has a great effect on the LSPI frequency. To study the auto-ignition characteristics of lubricant, an innovative single droplet auto-ignition test system for lubricant and its mixture is designed and developed, with better accuracy and effectiveness. The experiments are carried out by hanging lubricant droplets on the thermocouple node under active thermo-atmosphere provided by a small “Dibble burner”. The auto-ignition process of lubricant droplets is recorded by a high-speed camera. Influences of different base oil types, viscosities, calcium contents, initial droplet diameters, co-flow speeds, new oil, used oil and blending ratios of lubricant and gasoline on the ignition delay time of droplets are investigated at different droplet temperatures. The background co-flow field temperature varies from 823K to 1323K. Equivalent diameters of droplets, 0.99mm, 1.24mm and 1.63mm, generated by micro-syringes are compared for their characteristics of auto-ignition. The results show that the ignition delay time of all the droplets is significantly shortened with the increase of droplet temperature. When the droplet temperature is lower than 1073K, the ignition delay of droplets from Type III base oil is shorter than that of droplets from Type IV base oil. Besides, lubricant droplets with higher viscosities or larger initial diameters have a longer ignition delay. Furthermore, increasing both the calcium content and co-flow speed can obviously promote the auto-ignition process of droplets. Moreover, there is a critical blending ratio for gasoline to lubricant, whose value is between 20% and 30%. When it is lower than the critical blending ratio, the ignition delay of lubricant droplets increases with the rising of blending ratio. When it is higher than the critical blending ratio, the rule is contrary.

Yu, Yang, Pan, Kaifeng, Deng, Jun, Hu, Zongjie, Xie, Wei, Wu, Zhijun, Li, Liguang

Measurement of Fuel Distribution in a Small PFI Spark-Ignition Engine Using Tracer PLIF

2020-01-0786

4/14/2020

The distribution of fuel-air mixture inside the engine cylinder strongly influences the combustion process. Planar laser-induced fluorescence (PLIF) is commonly used for fuel distribution measurement, however, it is mostly reported on moderate- to large-sized engines. In the present work, PLIF is applied to measure the fuel distribution inside the cylinder of a small, four-stroke, port-fuel-injection (PFI), spark-ignition engine with displacement volume of 110 cm3. Iso-octane was used as the base fuel, and 3-pentanone (15% by volume) was added as a fluorescent tracer in the base fuel. The effect of equivalence ratio, considering ϕ = 1.2, 1.0, and 0.8, on in-cylinder fuel distribution was studied with low throttle opening of 25% at 1200 rpm. PLIF images were recorded at different crank angle degrees during both intake and compression strokes over a swirl measurement plane located at the TDC position. It was found that the fuel stratification was present from intake to even late compression. Also, no significant change in fuel distribution patterns was noted at different crank angle degrees for a given operating condition. Instantaneous PLIF images of the fuel distribution at 330 CAD during compression also showed a considerable variation from one cycle to the next. As expected, the fluorescence signal intensity was increased with the increase in equivalence ratio. Results also showed that the fuel distribution was much more noticeable near the diametrically opposite location to the spark plug on the tested engine, and continued to exist till late compression (i.e. 330 CAD).

Garg, Shubham, Mittal, Mayank, Sahu, Srikrishna, Lakshminarasimhan, V

Potential Analysis and Virtual Development of SI Engines Operated with Synthetic Fuel DMC+

2020-01-0342

4/14/2020

On the way to emission-free mobility, future fuels must be CO2 neutral. To achieve this, synthetic fuels are being developed. In order to better assess the effects of the new fuels on the engine process, simulation models are being developed that reproduce the chemical and physical properties of these fuels. In this paper, the fuel DMC+ is examined. DMC+ (a mixture of dimethyl carbonate (DMC) and methyl formate (MeFo) mainly, characterized by the lack of C-C Bonds and high oxygen content) offers advantages with regard to evaporation heat, demand of oxygen and knock resistance. Furthermore, its combustion is almost particle free. With the aid of modern 0D/1D simulation methods, an assessment of the potential of DMC+ can be made. It is shown that the simulative conversion of a state-of-the-art gasoline engine to DMC+ fuel offers advantages in terms of efficiency in many operating points even if the engine design is not altered. This is mainly due to the higher knock resistance and the lower temperatures in the intake stroke resulting from the higher amount of evaporated fuel. For a fixed amount of fuel energy, a lower air mass flow rate is needed, making the fuel particularly interesting for down-sizing concepts. Therefore, the engine design is adapted for the new fuel to take full advantage of the fluid properties. In a first step, the adaptions include the compression ratio, the engine displacement and the turbocharger matching. A considerable efficiency gain in the whole operating range can be demonstrated, making DMC+ a highly promising prospective for future SI engines.

Wagner, Cornelius, Grill, Michael, Keskin, Mahir-Tim, Bargende, Michael, Cai, Liming, Pitsch, Heinz

Effect of Fuel and Lubricant on Engine Vibration

2020-01-1015

4/14/2020

Vibration problems in internal combustion engines produce premature wear on the internal components of the engine, which contributes both to reduce the lifespan of the engine itself as well as cause discomfort to the occupants of the vehicle. Thus, since it is impossible to totally eliminate vibrations from engines, it is important to understand the sources of vibration production and control them to acceptable levels. The general objective of this paper is to measure the vibration in the areas that undergo greater efforts due to the processes of combustion and mechanical forces. These areas are the fixed bearings located to the extremes of the crankshaft. The specified objective of this study is to correlate these levels of crankshaft engine vibration relative to the fuel used, ethanol and gasoline, and assess the influence of lubricant oils on the vibration levels as a function of the viscosity of the lubricant. The results demonstrated that the vibration intensity of the engine increases with increasing engine speed and load. In all operating conditions, the ethanol-run engine has higher vibration intensities than the gasoline-run engine. For the same type of fuel, an oil of higher viscosity attenuates the level of vibration of the engine. Measurements show an average increase of 18% of transverse vibration and 12% of longitudinal vibration in the crankshaft of the engine running on ethanol in relation to gasoline with low viscosity lubricant and 14% and 10% with higher viscosity lubricant.

Santana, Claudio Marcio, Mautone, Jose, Gutierrez, Juan, Almeida Junior, Hélder

The Isochoric Engine

2020-01-07964/14/2020

For the gasoline engine, the isochoric process is the ideal limit of the ideal processes. During the project, a combustion engine with real isochoric boundary conditions is built. A “resting time” of the piston for several degrees crank angle in the top dead center (TDC) can be realized with a special crank drive. This crank drive consists of two crankshafts with different strokes, which are combined. The two crankshafts rotate with a ratio of two to one in opposite directions. The total stroke corresponds to the amount of the first crankshaft, so it is possible to investigate different strokes of the second crankshaft in the same crankcase. Different “resting times” can be achieved by different strokes of the second crankshaft. A specific combination of both crankshafts make a stroke possible which corresponds to that of a conventional combustion engine. In addition to the standard cylinder pressure sensor, a quick surface temperature probe is also used as supplementary measurement technology. The influence of isochoric combustion is studied with constant air mass and constant lambda at three different strokes of the small crankshaft.

Burger, Benjamin, Bargende, Michael

Smart Spark Plug for Proper Combustion Timing in Gasoline Engines and Detection of Misfire and Knock

2020-01-07904/14/2020

Internal combustion engines are required to achieve production goals of better fuel economy, improved fuel economy and reduced emissions in order to meet the current and future stringent standards. To achieve these goals, it is essential to control the combustion process using an in-cylinder combustion sensor and a system that produces a feedback signal to the ECU. This paper presents a system based on combustion ionization that includes a newly developed smart spark plug capable of sensing the whole combustion process. A unique feature of the smart spark plug system is its ability to sense the early stages of combustion and produce a complete ion current signal that accurately identifies and can be used for the control of the start of combustion. This is not the case for the conventional spark plug where the start of combustion cannot be determined from the ion current signal because its early part is distorted or completely overshadowed by the strong electromagnetic field produced by the spark ignition system. In addition to its ability to detect and control the start of combustion, the new system can detect other combustion related problems such as misfire and knock. The paper describes the construction of the smart spark plug and compares its ion current signal with that produced by the conventional spark plug. The new system, developed and patented by IC LLC, can be applied in current production spark ignition engines as well as for the development of future advanced concepts engines.

Assaad, Kamal, Henein, Naeim A.

Energy Enhanced Adaptive Spark Ignition for Lean Combustion Initiation

2020-01-08414/14/2020

For internal combustion engine systems, lean and diluted combustion is an important technology applied for fuel efficiency improvement. Because of the thermodynamic boundary conditions and the presence of in-cylinder flow, the development of a well-sustained flame kernel for lean combustion is a challenging task. Reliable spark discharge with the addition of enhanced delivered energy is thus needed at certain time durations to achieve successful combustion initiation of the lean air-fuel mixture. For a conventional transistor coil ignition system, only limited amount of energy is stored in the ignition coil. Therefore, both the energy of the spark discharge and the duration of the spark discharge are bounded. To break through the energy limit of the conventional transistor coil ignition system, in this work, an adaptive spark ignition system is introduced. The system has the ability to reconstruct the conductive ion channels whenever it is interrupted during the spark discharge. Furthermore, thanks to the addition of a spark energy management module, the amplitude and the duration of the discharge current are both controllable. As a result, the amplitude of the discharge current can be maintained at a relatively high level within the duration of the spark discharge. Whenever the system detects the interruption of the spark current by external disturbances, such as strong air-motion, the embedded control algorithm in the proposed ignition system would command the generation of multiple consecutive spark breakdowns to reconstruct the conductive ion-channels. With the reestablishment of the conductive ion channels, spark discharge reforms inside the air-fuel mixture. This technique has the potential to improve the flame kernel development in lean air-fuel mixtures. Preliminary ignition tests are conducted in a constant volume optical vessel to demonstrate the performance of the proposed ignition system.

Tan, Qingyuan, Zheng, Ming, Wang, Linyan, Li, Liguang, Yu, Xiao, Zhu, Hua

Probing Spark Discharge Behavior in High-speed Cross-flows through Modeling and Experimentation

2020-01-11204/14/2020

This paper presents a combined numerical and experimental investigation of the characteristics of spark discharge in a spark-ignition engine. The main objective of this work is to gain insights into the spark discharge process and early flame kernel development. Experiments were conducted in an inert medium within an optically accessible constant-volume combustion vessel. The cross-flow motion in the vessel was generated using a previously developed shrouded fan. Numerical modeling was based on an existing discharge model in the literature developed by Kim and Anderson. However, this model is applicable to a limited range of gas pressures and flow fields. Therefore, the original model was evaluated and improved to predict the behavior of spark discharge at pressurized conditions up to 45 bar and high-speed cross-flows up to 32 m/s. To accomplish this goal, a parametric study on the spark channel resistance was conducted. Then, the parameters that best fit the experimental data were obtained using the least-squares fit technique. Results show that the model captured the spark discharge characteristics including the occurrence of the spark blowouts and re-strikes that were observed experimentally. It was also shown that the voltage and current waveforms of the spark discharge are correlated to the flow velocity across the spark plug gap. Further investigations were also performed to study the stretching rate of the spark channel under high-speed cross-flows.

P. Zadeh, Mary, Schmidt, Henry, Lee, Seong-Young, Naber, Jeffrey

Experimental Investigation of the Influence of Ignition System Parameters on Combustion in a Rapid Compression-Expansion Machine

2020-01-11224/14/2020

Lean burn combustion concepts with high mean effective pressures are being pursued for large gas engines in order to meet future stringent emission limits while maintaining high engine efficiencies. Since severe boundary conditions for the ignition process are encountered with these combustion concepts, the processes of spark ignition and flame initiation are important topics of applied research, which aims to avoid misfiring and to keep cycle-to-cycle combustion variability within reasonable limits. This paper focuses on the fundamental investigation of early flame kernel development using different ignition system settings. The investigations are carried out on a rapid compression-expansion machine in which the spark ignition process can be observed under engine-like pressure and excess air ratio conditions while low flow velocities are maintained. The schlieren setup for high-speed optical investigations of the area of the spark plug electrodes is described and a suitable post-processing routine is introduced. The influence of different spark current durations on early flame kernel formation is investigated using a modulated capacitive discharge ignition (MCDI) system. The outcomes reveal that a short spark current duration results in a slower increase and higher standard deviation of the flame area during the early phase of combustion. Moreover, stable flame initiation appears to require a minimum spark current duration. The methodology introduced in this paper will be applied in detailed investigations of other spark plug geometries and ignition settings in order to shed more light on the ignition of lean mixtures.

Kiesling, Constantin, Pirker, Gerhard, Tilz, Anton, Oppl, Thomas, Nickl, Andreas, Wimmer, Andreas, Meyer, Georg

Optical Diagnostics of Isooctane and n-Heptane Isobaric Combustion

2020-01-11264/14/2020

Isobaric combustion has demonstrated a great potential to reach high thermodynamic efficiency in the advanced Double Compression Expansion Engine (DCEE) concept. It appears as one of few viable choices for applications with high-pressure combustion. At these conditions, releasing heat at a constant pressure minimizes the peak in-cylinder pressure and, hence, mitigates excessive mechanical stress on the engine. This study focuses on the effect of fuels on the multiple-injection isobaric combustion. A single-cylinder heavy-duty engine was utilized to test and compare the isobaric combustion with pure isooctane and n-heptane fuels. The engine was equipped with an optical piston to allow a bottom-view of the combustion chamber. The interactions of multiple injections and the combustion behavior were studied using high-speed acquisition of chemiluminescence. The examined isobaric cases have a peak pressure of 70 bar. For cases with high soot luminosity, a short band-pass filter was used to avoid image saturation. Fuels with short ignition delay time such as n-heptane are usually used for isobaric applications as they offer good controllability of injections. However, the study herein demonstrates that isobaric combustion can be achieved even with high octane number fuels such as isooctane. The dwell time between injections is much larger for isooctane, which allows enhanced mixing of the fuel jets with air and thus a partially premixed combustion behavior. The high-speed imaging demonstrated evidence of flame extinguishing during the sequential injection of n-heptane. This contributes to the staging of the heat release rate.

Al Ramadan, Abdullah S., Nyrenstedt, Gustav, Ben Houidi, Moez, Johansson, Bengt

Experimental Study on the Characteristics of Short Circuits and Restrikes of Spark Channels

2020-01-11234/14/2020

Ignition performance is critical for the implementation of diluted combustion for spark-ignition engines. The short circuit and restrike phenomena can influence the initial ignition volume and discharge duration which are important for the stable ignition processes. In this study, the short circuits and restrikes of spark channels are studied with various flow velocities, spark plug gaps and discharge energies. The development of the spark channels is captured by using the direct imaging technique with a CMOS camera equipped with an image intensifier. A multi-coil ignition system is designed to enable flexible control of discharge energies. The results show that the spark plug gap size is a critical parameter to suppress the phenomena of short circuits and restrikes. With the enlargement of spark plug gap, the maximum and average lengths of the spark channel effectively increase. Meanwhile, increasing discharge power is another effective method to improve the short circuit and restrike phenomena. However, for the discharge strategy of single strike, further increasing the discharge power cannot improve the restrike phenomena. The spark channel growth rate has no correlation with the spark plug gap and the discharge energy, but linearly relating to the flow velocity around the spark plug gap. An enhanced flow velocity increases the events of short circuit and restrike. The restrike voltage increases with decrease of the discharge current or increase of the flow velocity, while, the restrike voltage is lower than the breakdown voltage of the spark onset from the same discharge process. Finally, a new spark plug prototype is given to suppress the short circuit and enhance the spark plasma channel under high-velocity flow conditions.

Huang, Shuai, Li, Tie, Wang, Ning, Wang, Xinran, Yang, Zhenyi, Yu, Xiao, Zheng, Ming

Investigation of the Impacts of Spark Plug Orientation on Combustion Stability under Lean SI Operation

2020-01-11214/14/2020

The increasingly stringent restrictions on vehicle emissions and fuel consumption are driving the development of gasoline engines towards lean combustion. Increasing ignition energy has been considered an effective way to achieve lean operation conditions. To further improve the lean limit of engine combustion, the influence of the spark plug orientation on the combustion stability under lean operation should be explored. In this investigation, the original machine spark plug orientation, 90 degrees clockwise rotation, and 180 degrees clockwise rotation are studied to analyze the impact of spark plug orientation. The combustion experiment was carried out under the condition of low excess air ratio of the original machine and high excess air ratio with a 450 mA high energy ignition. It is found that changing the orientation of the spark plug had little effect on combustion at low excess air ratio; however, under high excess air ratio (ultra-lean operation), spark plug orientation had a great influence on combustion stability. The combustion stability can be significantly improved when the spark plug orientation is vertical to the intake direction. What’s more, we found that when the engine speed was low as 1000rpm, the effects of the spark plug orientation were not very clear. However, when the engine speed increased to 2000rpm, the lean operation limit can be improved from an excess air ratio of 1.78 to 1.96 by adjusting the orientation of the spark plug.

Gu, Qifan, Xu, Min, Ye, Chang, Hung, David, Li, Xuesong

A Novel Design of Engine Misfire Detection System Suitable for Small Capacity S.I. Engine for Two Wheeled Vehicle

2020-01-02674/14/2020

As per the OBD II regulations, it is essential to detect and monitor the misfire event in an I.C. engine. Misfiring of an I.C. engine affects the quality of combustion and degrades the performance of catalyst convertor which can lead to an increase of emissions. Misfire event can be categorized as partial or complete, based on amount of combustion occurred during that particular engine cycle. Most of the production engine for non-two wheeler vehicle identifies misfire by monitoring angular acceleration of the engine crank-shaft. However, single cylinder engine with lower capacity (less than 300 cubic centimeter) provides challenges to identify misfire due to low mechanical inertia of the I.C. engine using the same approach. The problem of misfire identification for this category of I.C. engine turn out to be more challenging due to presence of various load disturbances on the powertrain. Ion current sensing is one of the alternate method to detect misfire, which received good attention during the last decade of the previous century. When the air-fuel mixture ignites inside the I.C. engine cylinder, air particles get ionize. By applying a suitable high-voltage on spark plug, it is possible to measure the ion current as the amount of ion current reflects the level of ionization of air fuel mixture. The ion current measurement system presented in this paper is implemented in a production vehicle ignition system for two wheeled vehicles. The vehicle ignition system is unique due to the shorted terminals of high & low voltage sides. Due to the shorted primary and secondary connection, it is challenging to implement ion current measurement system using available research work. The proposed novel design of ion current measurement system accommodates the above constraint. The ion current signal is captured during normal combustion event as well as by creating misfire in the combustion. There are significant changes observed in the ion current signal with and without misfire. The information extracted from the ion current signal is utilized to detect the misfire. The proposed design is analyzed with suitable 1D theoretical model of the ignition system.

Bagade, Monika Jayprakash, Das, Himadri Bhushan, Raveendranath Sr, Arjun, Jabez Dhinagar, S

Studying Ignition Delay Time of Lubricant Oil Mixed with Alcohols, Water and Toluene in IQT and CVCC

2020-01-14224/14/2020

The auto-ignition of liquid fuel and lubricant oil droplets is considered as one of the possible sources of pre-ignition. Researchers are continually finding new ways to form advanced lubricant oil by changing its composition and varying different oil additives to prevent the occurrence of this event. This study investigates additives for lubricants to suppress its auto-ignition tendency. Three sets of mixtures were prepared. The first set of mixtures were prepared by adding different alcohols namely ethanol, and methanol to the commercial lubricant oil (SAE 15W-40) in ratio of 1 - 5 % by vol The second set of mixtures were prepared by mixing SAE 15W-40 with aforementioned alcohols (1 % vol.) and H2O (1 % vol.). Lastly, the third set of mixtures were prepared by adding toluene to SAE 15W-40 in (1 % - 5% by vol.). Two experimental setups were used in the current work. An Ignition Quality Tester (IQT) was used to investigate the mixtures’ ignition delay time (IDT) following standard ASTM D6890 procedure, and a larger constant volume combustion chamber (CVCC) was used to investigate the combustion characteristics of a suspended single oil droplet. In the CVCC chamber, the droplet was ignited in an atmosphere of air at 300 °C and pressure ranging from 4 bar - 22 bar at 6 bar interval pressures. IDT of lubricant oil was considered as the base IDT, which was compared to those of other mixtures. Addition of alcohols and water in lubricant oil showed a significant increase in IDT compared to toluene addition. On the contrary, the addition of toluene resulted in a decrease in IDT. Among the alcohols, methanol addition showed higher IDT than ethanol addition. Alcohols increased the IDT effectively only beyond the addition of > 4 % by vol.

Maharjan, Sumit, Elbaz, Ayman, Mitsudharmadi, Hatsari, Roberts, William

Devices Providing Backfire Flame Control for Gasoline Engines in Marine Applications

J1928_202002 (Historical)2/25/2020

This SAE Standard covers the minimum requirements for design, construction, and testing of devices to prevent the propagation of backfire flame from within the gasoline engine to the surrounding atmosphere.

Marine Technical Steering Committee

Internal Combustion Engines - Piston Vocabulary

J2612_202002 (Current)2/18/2020

This SAE standard defines the most commonly used terms for pistons. These terms designate either types of pistons or certain characteristics and phenomena of pistons.

Piston and Ring Standards Committee

Ignition System Nomenclature and Terminology

J139_202002 (Current)2/10/2020

To provide standard terminology and definitions with regard to ignition systems for spark-ignited internal combustion engines.

Ignition Standards Committee

A Study of Ignition Method for Gas Heat Pump Engine Using Low Temperature Plasma

2019-32-06221/24/2020

Low temperature plasma ignition has been proposed as a new ignition technique as it has features of good wear resistance, low energy release and combustion enhancement. In the authors’ previous study, lean burn limit could be extended by low temperature plasma ignition while a voltage drop during discharge, leading to the transition to arc discharge, was found. In this study, the structure of plug and power supply’s performance with steep voltage rising with time, dV/dt, are examined to investigate the effects on combustion performance. As a result, comparing three power sources of conventional, IES and steep dV/dt, steep dV/dt showed small cycle-to-cycle variation and shorter combustion period, leading to higher peak value of the rate of heat release and better indicated thermal efficiency by relatively 6% and 4% compared to CIC and IES, respectively.

Moriyoshi, Yasuo, Matsumoto, Osamu, Kuboyama, Tatsuya, Tsukamoto, Takahiro, Kinuzawa, Yoshiyuki, Maeshima, Hideaki

Tumble Flow Enhancement Applied for Low-Load Condition of Engines by Utilizing Reverse Flow Phenomenon in Intake Port

2019-32-05091/24/2020

We established a technology that can enhance the tumble flow in the cylinder only in a partial load range of the engine without the need to use any intake path switching mechanisms. Firstly, we attempted to understand the basic phenomena of intake flow by using a CFD model, while using a butterfly throttle valve in a straight pipe. By doing this, we were able to observe the reverse flow of intake air that appears after the intake air has passed the throttle valve when the throttle valve opening is 30% or less. This reverse flow is generated mainly in the flow that has passed the trailing edge of the throttle valve. At both sides of the trailing edge opening, the flow is slowed down by diffusing. The flow is then pulled into the low-pressure zone created behind the throttle valve. In addition, a part of the reverse flow merges with the air flowing on the leading-edge side. Next, we confirmed that installing a flow separator behind the throttle valve that vertically divides the flow can successfully capture the reverse flow into one of the two flow paths. Furthermore, we confirmed that optimizing the separator position can capture most of the flow into one path, thereby gaining the required amount of flow that can generate tumble in the combustion chamber. By applying the above results to an actual engine, we validated the effect through a CFD flow analysis and also steady flow tests. As a result, we confirmed that this system can enhance tumble within a partial load range of the engine to a level that is equivalent to that obtained by a tumble port that has a flow path switching mechanism.

Nakamura, Yohei, Inoue, Yosuke, Fujikubo, Makoto

Analysis of Cycle-to-Cycle Variation in a Port Injection Gasoline Engine by Simultaneous Measurement of Time Resolved PIV and PLIF

2019-32-05521/24/2020

Cycle-to-cycle variation (CCV) of combustion in low load operation is a factor that may cause various problems in engine operation. Variable valve timing and variable ignition timing are commonly used as a means to reduce this variation. However, due to mountability and cost constraints, these methods are not feasible for use in motorcycle engines. Therefore, development of an engine with minimal CCV without utilizing complicated mechanisms or electronic control is required. CCV of combustion may be caused by fluctuations in in-cylinder flow, air-fuel mixture, temperature, residual gas and ignition energy. In this study, the relationship between CCV of combustion, in-cylinder flow fluctuation and air-fuel mixture fluctuation was the primary focus. In order to evaluate in-cylinder flow fluctuation, Time Resolved Particle Image Velocimetry (TR-PIV) technique was utilized. In addition, Planar Laser Induced Fluorescence (PLIF) technique was used to measure spatial distribution of the mixture. These two visualization techniques were used together to measure continuous combustion cycles. The fluctuation of net IMEP can be explained by the fluctuation of Turbulence Kinetic Energy (TKE) and fuel concentration. In most cycles, net IMEP was correlated with TKE. In the remaining cycles, net IMEP was correlated with fuel concentration. The contribution of each factor towards net IMEP is to be discussed. It has been also confirmed that TKE fluctuation is caused by fluctuation in the tumble vortex structure, as shown in the authors' previous study [2] [13].

HARAMIISHI, Santa, WATANABE, Takahiro, IIDA, Minoru, HOKIMOTO, Satoshi, KUBOYAMA, Tatsuya, MORIYOSHI, Yasuo

Influence of Zn, Mo, P, S-contained Engine Oil Additives on Abnormal Combustion in a Spark Ignition Engine

2019-32-05861/24/2020

A Spark Ignition Engine has some kinds of problem to be solved over many years, one of them is abnormal combustion; Low-speed pre-ignition (LSPI) under low-speed, high-load driving conditions for vehicle, and pre-ignition under longterm operation without cleaning a combustion chamber for gas cogeneration. As a cause for abnormal combustion, engine oil droplets diluted by liquid fuel and peeled combustion deposits delivered from engine oil are proposed. In this study, experiments were conducted focusing on engine oil additives having different chemical structure and abnormal combustion behavior. A four-stroke side-valve single cylinder engine that allowed in-cylinder visualization of the combustion flame was used in the experiments. The experimental results showed that the influence of DTC additive on abnormal combustion is small and the zinc component contained in the DTP additives had the effect of advancing the autoignition timing.

Izako, Takuya, Iijima, Akira, Kusumoto, Tatsuya, Utaka, Toshimasa

Temperature Calculation Methodology of Pre Chamber With Homogeneous Charge

2019-36-02031/13/2020

The methodology for temperature calculations of homogeneous prechamber must be analyzed from a one-dimensional analytical model so that it is possible to determine the temperature profiles during the filling and emptying of the gases, so that it can avoid abnormalities such as increase of Forces, deformation / breaking, performance limitations, increased probability of detonation, increase of NOX and increase in the probability of pre-ignition. The equations of conservation of energy and of the state of gases are used to base the calculations, following the hypothesis that the flow is transient, comprehensible and one-dimensional; The fluid in the control volume is in the gaseous state and the fuel is already injected into the gas phase following the ideal gas equation. A homogeneous mixture is considered to generate a poor mixture in the pre-chamber.

MACHADO, L.F.G, FERREIRA, TIAGO S., RODRIGUES FILHO, F. A., MOREIRA, T. A. A.

Effects of Coolant Temperature and Fuel Properties on Soot Emission from a Spark-ignited Direct Injection Gasoline Engine

2019-01-235212/19/2019

Effects of measurement method, coolant temperature and fuel composition on soot emissions were examined by engine experiments. By reducing the pressure fluctuation in the sampling line, the measured soot emissions with better stability and reproducibility could be obtained. With lower coolant temperatures, larger soot emissions were yielded at much advanced fuel injection timings. Compared to gasoline, soot emissions with a blend fuel of normal heptane, isooctane and toluene were significantly decreased, suggesting the amounts of aromatic components (toluene or others) should be increased to obtain a representative fuel for the predictive model of particulate matter in SIDI engines.

Xiong, Qian, Gupta, Ankur, Kuboyama, Tatsuya, Moriyoshi, Yasuo, Suzuki, Hisakazu, Takeda, Takuya, Akihama, Kazuhiro, Hashimoto, Jun

Ignition of Individual Droplets in a Reactive Fuel/Air Mixture behind Reflected Shock Waves

2019-01-216212/19/2019

Multiphase-induced ignition is frequently discussed as a trigger for early ignition in internal combustion engines. In this context, we investigated the ignition process of single lubricant-oil droplets and their interaction with the bulk air/fuel mixture in a high-pressure shock tube, mimicking oil-fuel interaction in turbocharged internal combustion engines at the end of the compression stroke. A fast micro-dispensing injector released single fuel or lubricant oil droplets with a diameter of 200±50 µm into shock-heated fuel/air mixtures consisting of PRF95 and synthetic air. The injector was flush-mounted in the sidewall of the shock tube. The droplets were released into the gas after the passage of the reflected shock waves at post-shock conditions of 2 MPa and 750-950 K. With a high-frame-rate color camera, the entire evolution of droplet injection and ignition was traced in space and time through a large sapphire window in the endwall of the shock tube. A high-repetition-rate laser at 532 nm was used to illuminate the droplets. The light scattered by the droplets was detected in the green channel of the camera, whereas ignition and soot luminosity were detected in the blue and red channel, respectively. From the camera images the time for the appearance of first detected kernel related to local ignition (originating from either droplet or gaseous ignition) was determined. Additionally, the volume ignition that proceeds after an ignition delay time was determined from the OH* emission time-trace from a photomultiplier tube. It was found that the oil-droplet injection had an influence on the local ignition whereas the ignition delay time was reduced in the low temperature range only.

Niegemann, P., Fikri, M., Kaiser, S. A., Schulz, C.

Using RON Synergistic Effects to Formulate Fuels for Better Fuel Economy and Lower CO2 Emissions

2019-01-2155

12/19/2019

The knock resistance of gasoline is a key factor to decrease the specific fuel consumption and CO2 emissions of modern turbocharged spark ignition engines. For this purpose, high RON and octane sensitivity (S) are needed. This study shows a relevant synergistic effect on RON and S when formulating a fuel with isooctane, cyclopentane and aromatics, the mixtures reaching RON levels well beyond the ones of individual components. The same is observed when measuring their knock resistance on a boosted single cylinder engine. The mixtures were also characterized on a rapid compression machine at 700 K and 850 K, a shock tube at 1000 K, an instrumented and an adapted CFR engine. The components responsible for the synergistic effects are thus identified. Furthermore, the correlations plotted between these experiments results disclose our current understanding on the origin of these synergistic effects. This study concludes that this synergistic effect encourages formulating highly paraffinic fuels for lower specific fuel consumptions and CO2 emissions. Thus, paraffins are still relevant compounds to formulate highly efficient gasolines, despite their low octane sensitivity when individually considered. Furthermore, the CFR engine is still the best known device to anticipate synergistic effects in gasoline's knock resistance, through the Octane Index (OI = RON - K.S). A sensitivity study on the “K value” of the octane index shows that octane sensitivity mainly drives the gasoline performance for the low-sensitivity fuels while RON also drives it for the high-sensitivity ones.