Browse Topic: Jet engines

Items (1,095)

A Review of Literature on the Relationship Between Gas Turbine Engine Lubricants and Aircraft Cabin Air Quality

11/26/2025

There has been a recent upsurge in interest from the media concerning the quality of the environment within aircraft cabins and cockpits especially in the commercial world. This has included (although by no means been limited to) the air quality, with particular reference to the alleged effects of contamination from the aircraft turbine lubricant. Possible exposure to 'organophosphates' (OPs) from the oil has raised special concerns from cabin crew. Such is the concern that government organisations around the world, including Australia, USA and UK, have set up committees to investigate the cabin air quality issue. Concern was also voiced in the aviation lubricants world at the way in which OP additives in turbine lubricants were being blamed in some reports for the symptoms being experienced by air crew and passengers. SAE Committee E-34 therefore decided that it should gather as much available information on the subject as possible. This would then enable E-34 to participate in debates on the issue and help prevent a potentially erroneous decision regarding the future of OP based additives in turbine lubricants. It would also serve as an indicator of where any additional work may be necessary to properly gauge the role that turbine lubricants, and OP additives, play in cabin air quality. This report summarises recent documentation from the literature on this subject. The contents do not necessarily represent the views of the SAE or any of the members of the study group who produced this review. The literature falls into three categories: - Air quality (Section 5), which includes: future systems to improve air quality and research plans into investigating cabin air quality - Chemistry of turbine lubricants, phosphate esters (Section 6), including evaluation of products found in cabin air and thermal breakdown products of lubricants. - Toxicity evaluation of turbine oils and additives (Section 7).

E-34 Propulsion Lubricants Committee

Experimental Evidence to Influence Design of Novel Low Lubrication Method for Rotorcraft Secondary Lubrication Systems

F-0081-2025-0279

5/20/2025

This paper presents experimental research aimed at developing novel low lubrication methods for rotorcraft and jet engines, focusing on sustaining minimal lubrication to prevent catastrophic bearing failure during loss of lubrication (LoL) events or to increase fuel consumption performance on once-through, fuel-oil bearing lubrication engines. Utilizing two high-speed bearing test rigs simulating low and high thrust class engine conditions, the study establishes lower bounds for oil flow rates necessary to maintain thermal stability and prevent thermal runaway in hybrid ball bearings. These findings inform the design of the Zulu Pod (ZPod), a passively driven, self-contained oil delivery system that uses engine compressor bleed air to precisely meter lubricant flow. Engine test stand results demonstrate that replacing traditional fuel-oil lubrication with the ZPod system reduces thrust specific fuel consumption (TSFC) by an average of 7%, with up to 11% savings, without compromising engine thrust or bearing health. The ZPod offers a simplified, efficient alternative to fuel-lubricated systems by eliminating fuel diversion for lubrication, enhancing fuel efficiency, and maintaining bearing performance in attritable or single-use engines. Additionally, the study highlights the potential of minimal lubrication supplied by the ZPod to extend operational life during LoL scenarios, enabling safer aircraft recovery. Future work will focus on extending testing to higher thrust classes and optimizing ZPod designs for broader applications.

Boersma, Pieter, Currier, Todd, Ferrante, Jason, Rosenthal, Julius

Performance Analysis of a High-Speed Tiltrotor Aircraft Featuring VerdeGo Aero's VH-5 Hybrid-Electric Turbofan Engine

F-0080-2024-1235

5/7/2024

In the pursuit of High-Speed Vertical Takeoff and Landing (HSVTOL) platforms, VerdeGo Aero offers its VH-5 hybrid-electric turbofan as the answer to missions requiring high power, vertical lift, and jet-like speeds. To evaluate the possibility of designing a real HSVTOL aircraft around VerdeGo's VH-5 powerplant, this paper investigates the size and expected performance of a militarized spinoff of NASA's Class B, High-Efficiency Civil TiltRotor (HECTR) concept, which has been renamed the VerdeGo Hybrid-Electric Combative TiltRotor, or "VHECTR" for short. Through an in-depth conceptual weight buildup of four commonly proposed tiltrotor architectures, this paper suggests that an entirely new, turbofan-driven propulsion system is needed if modern day HSVTOL demands are to be met. Hence, a separate, yet more conventional "Modified HECTR" tiltrotor configuration is considered to contest the proposed, VH-5 powered VHECTR concept. However, the results of a full-scale aircraft comparison, aerodynamic analysis, and mission analysis alongside the V-22 Osprey indicate the VHECTR concept is more HSVTOL mission capable with greater time and fuel savings than any advanced tiltrotor system to date.

Roiati, Riccardo, Rice, Tyler, Steinfeldt, Brock, Nitzsche, Jasper, Anderson, Richard

Performance Analysis and Data Processing for the Mars Sample Recovery Helicopter in the Jet Propulsion Laboratory 25-ft Space Simulator

F-0080-2024-1357

5/7/2024

On April 19, 2021, Ingenuity became the first helicopter to fly on Mars at Jezero Crater, completing a total of 72 flights by the end of its mission. The success of Ingenuity resulted in various research efforts to further exploreMars via vertical flight, including two optimized Ingenuity-sized helicopters proposed to retrieve samples for the 2028 Mars Sample Return mission. To aid in the design process for the two proposed Sample Retrieval Helicopters, both heritage and optimized, increased diameter rotors were tested at the NASA Jet Propulsion Laboratory in the 25-ft Space Simulator. Three test campaigns were performed using the Ingenuity rotors and optimized Sample Retrieval Helicopter (SRH) rotors for several rotor speeds, densities, configurations, and collectives to identify performance limitations. These three test campaigns included the Ingenuity Engineering Design Model 1 (EDM-1) with and without a cruciform box, Transonic Rotor Test (TRT) rig, and SRH Dual Rotor Test (DRT). Experimental setup, test matrix, data processing, data quality, and performance results for EDM-1, TRT, and DRT campaigns are presented and discussed. Experimental results from the test campaigns will aid in future experimental methods and validation efforts for planetary rotorcraft exploration.

Schatzman, Natasha, Ridland, Paulina, Santillan, Diego, Glazebrook, Kenneth, Gehlot, Vinod, Meyn, Larry, Fillman, Michael, Chan, Athena

Aircraft Engine Life Cycle Cost Guide

AIR1939A (Current)

9/10/2021

AIR 1939 addresses communication of LCC data between equipment suppliers, aircraft engine producers, aircraft manufacturers, and users, as illustrated in Figure 1. The LCC data categories addressed include: research, development, test and evaluation (RDT&E); acquisition (initial procurement and investment); and operating and support (O&S) costs. While input and output formats are suggested, calculation procedures and cost methodology are specifically excluded since many LCC models preferred by the industry are company sensitive or proprietary (Figure 1). The relationship of LCC input data to program phase is described. Ground rules and assumptions are addressed. A glossary of LCC terms is provided. The LCC impact of propulsion systems on other aircraft systems is considered. This document was specifically developed for military propulsion system cost analysis. However, it is believed that a functional relationship exists between military and commercial Life Cycle Cost analysis and that with some interpretation, sections of AIR 1939 might be applicable to commercial propulsion systems as well. In summary, AIR 1939 provides a basis for LCC calculations, for monitoring of LCC status resulting from trade studies, and for tracking status against LCC goals in a consistent manner, thus permitting quantitative, comparable assessment. AIR 1939 guidelines recommend that a Life Cycle Cost presentation include consideration of overall cost rather than a sub-optimization of just one or a few cost elements.

LCLS Life Cycle Logistics Supportability

Weather Support to Deicing Decision Making (WSDDM) Winter Weather Nowcasting System

AS5537A (Current)

2/10/2021

The purpose of this SAE Aerospace Standard is to provide guidelines for the components and configurations that define the research and commercial versions of the Weather Support to Deicing Decision Making (WSDDM) winter weather nowcasting system.

G-12M Methods Committee

Design Considerations for Enclosed Turbofan/Turbojet Engine Test Cells

AIR4869B (Current)

2/1/2021

This SAE Aerospace Information Report (AIR) has been written for individuals associated with the ground-level testing of large and small gas turbine engines and particularly for those who might be interested in upgrading their existing or acquiring new test cell facilities.

EG-1E Gas Turbine Test Facilities and Equipment

Design Considerations for Enclosed Turbofan/Turbojet Engine Test Cells

AIR4869A (Historical)10/22/2020

EG-1E Gas Turbine Test Facilities and Equipment

Test Cell Instrumentation

AIR5026B (Current)10/21/2020

This document discusses, in broad general terms, typical present instrumentation practice for post-overhaul gas turbine engine testing. Production engine testing and engine development work are outside the scope of this document as they will typically use many more channels of instrumentation, and in most cases will have requirements for measurements that are never made in post-overhaul testing, such as fan airflow measurements, or strain measurements on compressor blades. The specifications for each parameter to be measured, in terms of measurement range and measurement accuracy, are established by the engine manufacturers. Each test cell instrument system should meet or exceed those requirements. Furthermore, each instrument system should be recalibrated regularly, to ensure that it is still performing correctly.

EG-1E Gas Turbine Test Facilities and Equipment

Determination of Costs and Benefits from Implementing an Engine Health Management System

ARP4176A (Current)4/28/2020

This ARP provides an insight into how to approach a cost benefit analysis (CBA) to determine the return on investment (ROI) that would result from implementing a propulsion Prognostics and Health Management (PHM) system on an air vehicle. It describes the complexity of features that can be considered in the analysis, the different tools and approaches for conducting a CBA and differentiates between military and commercial applications. This document is intended to help those who might not necessarily have a deep technical understanding or familiarity with PHM systems but want to either quantify or understand the economic benefits (i.e., the value proposition) that a PHM system could provide.

E-32 Aerospace Propulsion Systems Health Management

Electronic Warfare Weapon

TBMG-360682/1/2020

MBDA Hertfordshire, UK +44 (0)1438 752000

Aircraft Engine Technology Review - The Pathways for an Efficient, Cleaner and Quieter Aviation Industry

2019-36-01751/13/2020

The aviation industry has been submitted to a set of environmental and commercial drivers that have led it to pursue engine technologies focused on the efficiency improvement, greenhouse (CO2) and pollutant (NOx and PM) emissions reductions, as well as noise abatement.The effort to comply with the ambitious long term environmental and efficiency targets set by the regulatory authorities has driven the aeronautic industry in a technological research effort. In the medium term, the aviation industry's strategy for commercial aviation is to focus on the advanced, but rather conventional propulsion systems (mainly turbofan engines). In this scenario, technological efforts have focused basically on enhancing thermal efficiency, through advanced core engines, as well as improving propulsive efficiency, through the use of low pressure systems (basically reduced pressure ratio and increased engine bypass ratio). To reach these objectives, a set of technological platforms has been proposed, with some already on an operational/commercial level, while others still in a prototype category. In this context, engine manufacturers have given a special focus on some technological approaches, like Ultra High Bypass Ratio (UHBPR) Geared Turbofans (GTF), Three Spool Turbofan (3STF), Counter-Rotating Open Rotor (CROR), Intercooled Turbofan (ITF) and Bleedless Engine (BE). This work is supposed to present, into a review format, an overview of the aforementioned technology platforms, demonstrating their potential to meet the efficiency and environmental requirements, their maturity level, as well as report any cases of operational experience available in the technical literature.

Barbosa, Fábio Coelho

Marking Aircraft Components

TBMG-3568312/1/2019

Numbers are critical to the smooth functioning of the international aerospace industry. Regulatory authorities such as the Federal Aviation Authority (FAA) and the US Department of Defense (DoD) mandate that aero components be permanently marked to ensure authenticity and traceability throughout the supply chain and into service.

Metallization for SiC Semiconductors

TBMG-3570412/1/2019

Scientists at NASA’s Glenn Research Center have developed and patented improved ohmic contacts, and a fabrication method for them, that will speed the production of silicon carbide (SiC) sensors and electronics that operate in high-temperature, harsh environments.

Eddy Current Inspection of Circular Holes in Nonferrous Metallic Aircraft Engine Hardware

AS4787A (Current)10/14/2019

This SAE Aerospace Standard (AS) establishes minimum requirements for eddy current inspection of circular holes in nonferrous, metallic, low conductivity (less than 5% IACS) aircraft engine hardware with fasteners removed. The inspection is intended to be performed at maintenance and overhaul facilities on engine run hardware.

AMS K Non Destructive Methods and Processes Committee

Assessment of Numerical Cold Flow Testing of Gas Turbine Combustor through an Integrated Approach Using Rapid Prototyping and Water Tunnel

2019-28-005110/11/2019

In the present work, it is aimed at developing an integrated approach for combustor modeling involving rapid prototyping and water tunnel testing to assess the cold flow numerical simulations; the physical model will be subjected to cold flow visualization and parametric studies and CFD analysis to demonstrate its capability for undergoing rigorous cold flow testing. A straight through annular combustors is chosen for the present study because of it has low pressure drop, less weight and used widely in modern day aviation engines. Numerical Analysis has been performed using ANSYS-FLUENT. Three dimensional RANS equations are solved using k-ɛ model for the Reynolds numbers ranging from 0.64 x 105-1.5 x 105 based on the annulus diameter. Post processing the results is done in terms of jet penetration, formation of recirculation zone, effective mixing, flow split and pressure drop for different cases. Physical combustor models are fabricated using Rapid prototyping with Poly Lactic Acid material and approximated 2D combustor model is used for capturing important flow patterns using high speed camera in 2D water tunnel, and for pressure measurement in vertical flow water tunnel. Qualitative flow visualization study on 2D combustor model using 2D water tunnel reasonably compares with CFD results. It is also found that the percentage of total pressure drop normalized with the inlet total pressure of combustor is within the acceptable range (i.e. less than 10%) in CFD whereas in the physical cold flow testing, it has more deviation at the lower flow rate.

Senthilkumar, Sundararaj, Pugazhendhi, Ssheshan

Advanced Exergy Analysis of an Air Craft Gas Turbine Engine at Different Power Loading Operations

2019-01-18639/16/2019

The innovations in aircraft propulsion have been identified as the key parameter towards the progress in transportation. Continuous advancement in the performance and efficiency of propulsion has enabled aircraft to travel over larger distances with higher speed. Aviation is also responsible for approximately 2% of total greenhouse gas emission and is expected to grow around 3% by 2050. The present article aims to use the exergetic analysis of a turboprop engine which should be helpful in designing of such engines and also helps these engine users to regulate and select the operation modes. A gas turbine with film air cooling of turbine blades has been proposed to be the turboprop engine. The engine is analyzed on exergy point of view at different power loading operation modes and the performance is studied. Selected exergetic measures under consideration are Exergy Efficiency, Fuel Exergy Depletion Ratio, Relative Exergy Consumption Ratio, Exergetic Improvement potential and Productivity Lack ratio. The total fuel exergy depletion ratio of the turboprop engine is estimated to be around 64.7 % at 100% loading. Also, among the identified cycle components, combustion chamber is identified as the main source (~ 35%) of the exergy destruction and, thus is the biggest contributor to the overall irreversibility of the system. The exergy efficiency is observed to be minimum at 75 % mode and maximum for Take-off. The exergetic improvement potential of the thermodynamic inefficiencies increases with increase in fuel-air ratio from 75%-mode to Take-off mode. The combustor section of the engine has been identified as the greatest source of relative exergy consumption ratio (63 %) and productivity lack ratio (51 %) followed by the turbine and compressor sections (at take off mode).

Mohapatra, Alok Kumar, Hotta, Tapano, Choudhary, Tushar

Compensating the Effects of Ice Crystal Icing on the Engine Performance by Control Methods

2019-01-18629/16/2019

Aircraft equipment is operated in a wide range of external conditions, which, with a certain combination of environmental parameters, can lead to icing of the engine internal elements. Due to icing, the engine components performance characteristics change what leads to decrease in thrust, gas dynamic stability, durability, etc. Safe aircraft operation and its desired performance may be lost as a result of such external influence. Therefore, it is relevant to study the possibilities of reducing the icing effect with the help of a special engine control. The focus of this paper is to determine control methods of an aircraft gas turbine engine addressing this problem. The object of the study is a modern commercial turbofan with a bypass ratio of about 9. In this paper analysis of the effect of ice crystal icing on the engine components performance is conducted. To perform simulation of the engine performance under such impact, degraded components characteristics was introduced into physics-based turbofan model. Control algorithms for this model were developed applied to various regulated variables used in the setpoint controllers of modern engines (fan speed, engine pressure ratio, etc.). It allowed to evaluate an engine operation in ice crystal condition with each kind of controller. Additionally, the engine control method using a thrust value provided by the on-board engine model is considered. Simulation showed the ability to maintain baseline thrust with degraded engine components performance. According to calculation results, an optimal engine control method which allow compensating the negative effect of ice crystal icing is determined.

Gurevich, Oskar, Smetanin, Sergei, Trifonov, Mikhail

Landing Gear Integration into Aircraft Structure in Early Design Stage

2019-01-18909/16/2019

The demanded development towards various emission reduction goals set up by several institutions forces the aerospace industry to think about new technologies and alternative aircraft configurations. With these alternative aircraft concepts, the landing gear layout is also affected. Turbofan engines with very high bypass ratios could increase the diameter of the nacelles extensively. In this case, mounting the engines above the wing could be a possible arrangement to avoid an exceedingly long landing gear. Thus, the landing gear could be shortened and eventually mounted at the fuselage instead of the wings. Other technologies such as high aspect ratio wings have an influence on the landing gear integration as well. To assess the difference, especially in weight, between the conventional landing gear configuration and alternative layouts a method is developed based on preliminary structural designs of the different aircraft components, namely landing gear, wing and fuselage. Simplified parametric finite element structural models for the different components are introduced. These models are used to investigate different aircraft configurations with special regard on the landing gear integration. The structural models of the fuselage and the wing are sized according to defined load cases. After this first sizing step, the structural model of the landing gear is integrated and different landing gear load cases are applied. The developed methods aim to assess the impact of the different landing gear configurations, not only regarding the landing gear structure but also the surrounding support structure of the airframe. Results of the applied methods for aircraft configurations with different landing gear integration are presented and discussed.

Kling, Ulrich, Hornung, Mirko

Predictive CFD Auto-Tuning Approach for In-Cylinder Simulations of Two Small-Bore LDD Engines

2019-24-00339/9/2019

Tightening emission regulations and accelerating production cycles force engine developers to shift their attention towards virtual engineering tools. When simulating in-cylinder processes in commercial LDD DI engine development, the trade-off between run time and accuracy is typically tipped towards the former. High-fidelity simulation approaches which require little tuning would be desirable but require excessive computing resources. For this reason, industry still favors low-fidelity simulation approaches and bridges remaining uncertainties with prototyping and testing. The problem with low-fidelity simulations is that simplifications in the form of sub models introduce multi variable tuning parameter dependencies which, if not understood, impair the predictive nature of CFD simulations. In previous work, the authors have successfully developed a boundary condition dependent input parameter table. This parameter table showed outstanding results for lab-scale experiments for over 40 varying operating conditions. The objective in this paper is first to identify the necessary considerations to adjust for the inherent differences between lab-scale and real engine conditions and then implement this parameter table into industry relevant conditions. With this approach the appropriate simulation setup for a real EU6 diesel engine can be predefined by the boundary conditions without previous tuning iterations. The performance of the simulation will be assessed based on its capability to match experimental heat release and chamber pressure data. The approach shown here has the potential to remove the necessity of lengthy tuning iterations and lays the groundwork for novel auto-tuned and predictive in-cylinder simulations.

Nsikane, Daniel, Vogiatzaki, Konstantina, Morgan, Robert, Mustafa, Kenan, Ward, Andy

Aircraft Engine Icing Event Avoidance and Mitigation

TBMG-347387/1/2019

Innovators at NASA’s Glenn Research Center have developed a new means of avoiding and mitigating icing events for aircraft flying above 14,000 feet, dramatically improving aviation safety and reducing operating costs.

Wind Tunnel Measurements of Simulated Glaciated Cloud Conditions to Evaluate Newly Developed 2D Imaging Probes

2019-01-19816/10/2019

Instrumentation that has been used for characterization of mixed-phase and glaciated conditions in the past, like the OAP probes, are subject to errors caused by variations in diffraction on the images away from the object plane and by the discrete nature of their particle detection and sizing. Correction methods are necessary to consider their measurements adequate for high ice water content (IWC) environments judged to represent a significant safety hazard to propellers and turbofan engine operability and performance. For this reason, within the frame of EU FP7 HAIC project, instrumentation characterization and validation is considered a major element need for successful execution of flight tests campaigns. Clearly, instrumentation must be sufficiently reliable to assess the reproducibility of artificial clouds with high ice water content generated in icing tunnels. Instruments are required to measure these conditions with a sufficient level of accuracy for the purposes of the testing. Currently, there is an anticipated basic uncertainty of a factor of 2-5 when measuring clouds in-situ. This may be worse for thunderstorm core regions, because of the poorly measured ice particle sizes below 100 μm when using legacy instruments. Measurements below 100 μm are especially difficult for ice particles. In order to mitigate this measurement limitation, an innovative approach for imaging droplets and ice crystals was considered in this work. This method is based on Artium Technologies Inc. High Speed Imaging (HSI) instrument. The method utilizes a unique multi-beam illumination approach to control the depth of field, minimize out-of-focus image noise effects, and limit obscuration of particles in the sample volume produced by out-of-focus particles in the optical path. Rather than utilizing a linear array to acquire the images, a modern CMOS two-dimensional array imaging system is used. The lasers used for producing bright field shadow images are pulsed synchronously and have pulse duration of as little as 12.5 ns to “freeze” the particle motion. The response of the HSI will be reviewed on the basis of comparison with SPEC 2D-S by means of wind tunnel measurements for glaciated cloud conditions.

Esposito, Biagio M., Bachalo, William D., Leroy, Delphine, Schwarzenboeck, Alfons, Jurkat, Tina, Voigt, Christiane, Bansmer, Stephan

The Effect of Crosswinds on Icing at Turbofan Engine Inlet

2019-01-20246/10/2019

Ice accretion at engine inlet has a dangerous effect on the inlet airflow and shed ice would be ingested into the engine and cause compressor blades damage, and even combustors flame out. In order to analyze the effect of crosswinds on icing at turbofan engine inlet, a complete icing analysis method, which is based on the Messinger model and takes the influence of runback water into consideration, is constructed. The runback water is considered laminar flow and the flow direction is dominated by the bottom flow of air. The supercooled water droplets impingement, ice accretion and runback water characteristics and inlet distortion with and without ice were investigated at crosswinds speed of 15, 20, 25, 30 kt. The variation of local water collection coefficient β is unchanged at crosswind conditions, but the location of the maximum value and non-dimensional impact limits change with the crosswind, which move backward along the outer edge on the windward, and move along the inner edge on the leeward. The ice thickness on windward surface increases slightly near the stagnation point, and the outer icing limit occurs at more rear position with crosswinds. On leeward surface, the variation is opposite to the windward and the ice shapes present a more symmetrical distribution at stagnation point. On the smooth inlet surface, the inlet airflow at the fan is relatively uniform, and the total pressure ratio variation at the inlet lip also is regular as crosswind increases. Greatly losses of airflow occur after ice accretion at crosswind conditions, which cause uneven inlet airflow. The effect of the crosswind on ice accretion at the inlet should be considered when designing and optimizing anti-icing system. Otherwise, the ice formation under crosswind will deteriorate the inlet airflow quality and pose a hazard to aircraft safety.

Yang, Qian, Guo, Zhiqiang, Zheng, Mei, Dong, Wei

Numerical Investigation of the NASA Glenn Propulsion Systems Laboratory

2019-01-19246/10/2019

NASA Glenn Research Center’s Propulsion Systems Laboratory (PSL) allows ice-crystal ice accretion tests on jet engines. This pressurized wind tunnel facility allows engines to be operated at flight altitudes and temperatures. Steady state and unsteady computational fluid dynamics simulations were performed for the PSL geometry, including the spray bars with their supports, and the converging duct section. These simulation results help to characterize the performance of the tunnel and are important for understanding the flow and particle behavior leading up to the engine test section. The results indicate complex flow structures, with vortex shedding and non-uniform flow features. Flow separation is observed in several regions. Several flow features and vortices are seen to persist to the duct exit plane where the fan section of a jet engine would be mounted for testing. Unsteady simulations show that periodic vortex shedding is created by the spray bars, and that the generated crosswise vorticity is converted to streamwise and antistreamwise vorticity through the acceleration and stretching of the flow structures in the converging duct section. Flow nonuniformity is observed on the duct exit plane for both steady state and unsteady simulations with velocity deficits on the sides and bottom of the exit plane. Particles of various diameters were released from either the upstream inlet plane or the spray bars, and corresponding trajectory simulations predict that the larger diameter particles will exit the duct closer to the centerline of the tunnel. Particle distribution at the duct exit plane is not uniform and is influenced by the upstream tunnel geometry features. These three dimensional simulation results will inform future testing efforts.

Feier, Ioan

Microwave Technique for Liquid Water Detection in Icing Applications

2019-01-19306/10/2019

The partial melting of ingested ice crystals can lead to ice accretion in aircraft compressors, but accurately measuring the relatively small fraction of liquid water content in such flows is challenging. Probe-based methods for detecting liquid water content are not suitable for deployment within turbofan engines, and thus alternatives are sought. Recent research has described approaches based on passive microwave sensing. We present here an approach based on active microwave transmission and reflection, employing a vector network analyzer. Utilization of both transmission and reflection provides additional data over and above emission or transmission only, and permits a more controllable environment than passive sensing approaches. The paper specifically addresses the question of whether such an approach is viable within the context of representative icing wind tunnel and engine flow conditions. A quasi-thermal equilibrium approach is presented herein to estimate the melting ratio during microwave analysis of samples at 0 °C. Experimental results using microwaves in the 2.45GHz region are presented, and post-processing methods investigated. This is followed by an investigation of detection limits for ice accretion in the sub-gram range. The results indicate the potential of the technique, with a number of avenues evident for further research.

Leis, John, Buttsworth, David, Saeed, Ramiz, Saleh, Khalid, McGilvray, Matthew, Gillespie, David

Scaling Evaluation of Ice-Crystal Icing on a Modern Turbofan Engine in PSL Using the COMDES-MELT Code

2019-01-19206/10/2019

This paper presents preliminary ice-crystal icing (ICI) altitude scaling evaluation results of a Honeywell Uncertified Research Engine (HURE) that was tested in the NASA Glenn Research Center Propulsion Systems Laboratory (PSL) during January of 2018. This engine geometry features a hidden core design to keep the core less exposed. The engine was fitted with internal video cameras to observe various ice buildup processes at multiple selected locations within the engine core flow path covering the fan stator, the splitter-lip/shroud/strut, and the high pressure compressor (HPC) variable inlet guide vane (IGV) regions. The potential ice accretion risk was pre-determined to occur by using NASA’s in-house 1D Engine Icing Risk assessment code, COMDES-MELT. The code was successful in predicting the risk of ice accretion in adiabatic regions like the fan-stator of the HURE at specific engine operating points. However at several operating points during the test, liquid water was observed running along the shroud toward the variable IGV of the HPC regions with an air temperature well below freezing, thus no particle melting could have occurred due to heating from the air alone. It was reasoned that other sources of heat were present in that region. To account for these heat sources the inlet total temperature was adjusted to give a wet bulb temperature of 24 °F below the standard minimum wet bulb temperature of 492 °R to allow ice to accrete in the splitter-lip/shroud/strut region, which was determined from a reference case where hard ice was observed in that region. With that adjustment the COMDES-MELT code was successful in providing operating points where there was a risk of ice accretion during the test campaign. In addition to calculating possible conditions at different selected lower altitudes, simulations were run to determine potential inlet conditions that could lead to ice-crystal accretion along the prescribed stations where the cameras were available. From there, scaled test conditions were determined by best matching the following three icing related parameters of the reference condition: (1) the local air total wet bulb temperature, (2) the local ice crystal cloud melt ratio and (3) the engine fan face ice/water to air mass flux ratio of the ice crystal cloud. Instantaneous images taken from the time-lapsed movies of ice buildup were used along with the relevant thermodynamic data of air, water vapor and local icing condition to help evaluate how closely the proposed altitude scaling method could be used in ground based test facility to duplicate selected reference ICI features observed at specific location inside this engine at different scale altitudes. Discussions on observed limitation for engine icing scaling application from this test campaign and needed improvement are provided. A scaling test procedure to help identify potential ICI risk conditions and possible ice accretion locations of a new turbofan engine is evaluated in PSL.

Tsao, Jen-Ching

Ice-Crystal Icing Accretion Studies at the NASA Propulsion Systems Laboratory

2019-01-19216/10/2019

This paper describes an ice-crystal icing experiment conducted at the NASA Propulsion System Laboratory during June 2018. This test produced ice shape data on an airfoil for different test conditions similar to those inside the compressor region of a turbo-fan jet engine. Mixed-phase icing conditions were generated by partially freezing out a water spray using the relative humidity of flow as the primary parameter to control freeze-out. The paper presents the ice shape data and associated conditions which include pressure, velocity, temperature, humidity, total water content, melt ratio, and particle size distribution. The test featured a new instrument traversing system which allowed surveys of the flow and cloud. The purpose of this work was to provide experimental ice shape data and associated conditions to help develop and validate ice-crystal icing accretion models. The results support previous experimental observations of a minimum melt-ratio threshold for accretion to occur as well as the existence of a plateau region where the icing severity is high for a range of melt ratios. However, a maximum limit for melt ratio, which is suggested in the ice crystal icing literature, was not observed perhaps complicated by the potential for some supercooling of the water at these conditions.

Struk, Peter M., Agui, Juan, Ratvasky, Thomas, King, Michael, Bartkus, Tadas, Tsao, Jen-Ching

A Continuing Investigation of Diurnal and Location Trends in an Ice Crystal Icing Engine Event Database

2019-01-19646/10/2019

Due to ongoing efforts by the aviation industry, much has been learned over the last several years regarding jet engine power loss and compressor damage events caused by the ingestion of high concentrations of ice crystal particles into the core flow path. Boeing has created and maintained a database of such ice crystal icing (ICI) events to aid in analysis and further study of this phenomenon. This article provides a general update on statistics derived from the Boeing event database, and provides more details on specific event clusters of interest. A series of three flight campaigns have, over the past five years, collected in-situ data in deep convective clouds that will be used for the assessment of the new FAA CFR Part 33 ice crystal environmental envelope Appendix D, and the equivalent EASA CS-25 Appendix P. The most recent Boeing engine event study in 2015 focused on oceanic cloud systems that caused events in Southeast Asia, a region expected to have similar cloud properties as the first flight campaign in Darwin, Australia. The current study will examine ICI engine events over South America and Africa, which are caused by large deep convective continental clouds of the type that were not the main focus of the three Appendix D/P flight campaigns. Continental event clouds are compared to the previously studied oceanic event clouds, in order to ascertain whether any systematic differences exist that should be considered when assessing the representativeness of the flight campaign datasets. The results may also be useful to those developing nowcasting algorithms identifying high ice concentration regions using satellite measurements.

Bravin, Melissa, Strapp, J. Walter

Semi-Empirical Modelling of Erosion Phenomena for Ice Crystal Icing Numerical Simulation

2019-01-19676/10/2019

The aim of this work is to develop a semi-empirical model for erosion phenomena under ice crystal condition, which is one of the major phenomena for ice crystal accretion. Such a model would be able to calculate the erosion rate caused by impinging ice crystals on accreted ice layer. This model is based on Finnie [1] and Bitter [2] [3] solid/solid collision theory which assumes that metal erosion due to sand impingement is driven by two phenomena: cutting wear and deformation wear. These two phenomena are strongly dependent on the particle density, velocity and shape, as well as on the surface physical properties such as Young modulus, Poisson ratio, surface yield strength and hardness. Moreover, cutting wear is mostly driven by tangential velocity and is more effective for ductile eroded body, whereas deformation wear is driven by normal velocity and is more effective for brittle eroded body. Several researchers based their erosion modelling on these two phenomena such as Hutchings et al. [4] for deformation erosion, or Huang et al. [5] and Arabnejad et al. [6] for cutting and deformation erosion. The main work of this paper is to develop an erosion model for ice crystal impingement based on these two phenomena, and to show its capability to predict accretion shape by simulating experimental cases from the National Research Council of Canada (NRC). NRC’s Currie et al. ice crystal experiments [7] [8] realized in warm aerodynamic conditions, such as the one encountered in high icing severity areas of a turbofan engine, show accretion severity for a large range of liquid water content to total water content. In order to validate the erosion model based on solid/solid collision, this paper presents the simulation of the lower melting rate experiment. Results show fair agreement with experimental data and allow us to propose pertinent further work.

Charton, Virgile, Trontin, Pierre, Aouizerate, Gilles, Villedieu, Philippe

Aerospace Work Platforms - More than Meets the Eye

19AERP06_136/1/2019

Today's work platforms are far more complex than the simple designs of the past. For maintenance personnel in the aerospace industry to do their jobs effectively, they need to be able to get physically close to the equipment they are working on. This statement sounds obvious, but in order to meet this requirement, it is very important to utilize quality work platforms. Although most people are familiar with the basic uses of work platforms, there is not always much thought given to everything that goes into their design and fabrication. In years past, simple platforms were widely used for a variety of different work applications, however, much more is demanded of them in modern facilities. These increased demands have forced the work platform fabrication industry to evolve. The design and fabrication of today's platforms require manufacturers with expertise, experience, and skill. Fabricators and designers must incorporate specialized features in many areas never before seen or even considered. Safety, configurability, mobility, material selection, worker access, and utilities are all requirements that need to be considered.

Aerospace Work Platforms — More than Meets the Eye

TBMG-345456/1/2019

For maintenance personnel in the aerospace industry to do their jobs effectively, they need to be able to get physically close to the equipment they are working on. This statement sounds obvious, but in order to meet this requirement, it is very important to utilize quality work platforms. Although most people are familiar with the basic uses of work platforms, there is not always much thought given to everything that goes into their design and fabrication.

Design of Composite Materials for Improved Loss-of-Lubrication Survivability of Hybrid Rotorcraft Gears

F-0075-2019-14685

5/13/2019

Hybrid gears featuring steel teeth mated to a composite body provide the potential for significant weight savings in aerospace applications such as rotorcraft and geared turbofan engines. For hybrid gears to be viable for use in these applications, they must not degrade mechanical performance or thermal characteristics, particularly under loss-of- lubrication operation. The heat generated by loss-of-lubrication operation may be especially problematic for the fiber- reinforced polymer composite materials used in hybrid steel-composite gear prototypes. Initial hybrid gear design and testing is described in the literature, but no prior studies have investigated optimization of the composite material for thermal performance. In the study presented herein, conductive fibers and high-temperature polymers are introduced to make a composite material better suited to high-temperature and loss-of-lubrication. Channel-flow resin transfer molding was used to fabricate composites with a variety of configurations, including hybrid reinforcement alternating highly-conductive pitch-based carbon fiber plies with typical high-strength polyacrylonitrile (PAN)-based carbon fiber plies. Performance was evaluated by thermal conductivity measurement and compression strength testing. Finite element modeling was performed to quantify strength and stiffness requirements for the composite gear web and to investigate the effects of using plies of different stiffness in a hybrid laminate. Results of this study show that the in-plane thermal conductivity of composite laminates can be greatly increased by using hybrid reinforcement, but the hybrid gear web design must account for the low compression strength of the hybrid reinforcement to ensure that the structural integrity of the composite gear web is not compromised.

Waller, Matthew, Koudela, Kevin, McIntyre, Sean