Abstract In subsonic aircraft design, the aerodynamic performance of aircraft is compared meaningfully at a system level by evaluating their range and endurance, but cannot do so at an aerodynamic level when using lift and drag coefficients, CL and CD , as these often result in misleading results for different wing reference areas. This Part I of the article (i) illustrates these shortcomings, (ii) introduces a dimensionless number quantifying the induced drag of aircraft, and (iii) proposes an aerodynamic equation of state for lift, drag, and induced drag and applies it to evaluate the aerodynamics of the canard aircraft, the dual rotors of the hovering Ingenuity Mars helicopter, and the composite lifting system (wing plus cylinders in Magnus effect) of a YOV-10 Bronco. Part II of this article applies this aerodynamic equation of state to the flapping flight of hovering and forward-flying insects. Part III applies the aerodynamic equation of state to some well-trodden cases in fluid

Burgers, Phillip

An Aerodynamic Equation of State—Part I: Introduction and Aerospace Applications - QA Test Tatsiana

01-17-01-0001-TEST-REC04/19/2023

Burgers, Phillip

An Aerodynamic Equation of State—Part III: Applications to Fluid Statics and Dynamics

01-17-01-0003

04/19/2023

The aerodynamic equation of state is introduced in Part I and applies to selected aerospace systems. Part II applies it to the flapping of hovering and forward-flying biological fliers. This last Part III expands the aerodynamic equation of state by adding the potential energy term, assumed up to this point to be zero as the system and its trajectory is placed coplanar with an arbitrary reference potential plane. Part III applies the expanded equation of state to familiar and well-trodden fluid-static and fluid-dynamic cases selected from fluid mechanic textbooks.

Burgers, Phillip

An Aerodynamic Equation of State—Part II: Applications to Flapping Flight

01-17-01-0002

04/19/2023

Part I introduced the aerodynamic equation of state. This Part II introduces the aerodynamic equation of state for lift and induced drag of flapping wings and applies it to a hovering and forward-flying bumblebee and a mosquito. Two- and three-dimensional graphical representations of the state space are introduced and explored for engineered subsonic flyers, biological fliers, and sports balls.

Burgers, Phillip

An Aerodynamic Equation of State—Part I: Introduction and Aerospace Applications

01-17-01-0001

04/19/2023

In subsonic aircraft design, the aerodynamic performance of aircraft is compared meaningfullyby evaluating their range and endurance, but cannot do so atwhen using lift and drag coefficients,and, as these often result in misleading results for different wing reference areas. This Part I of the article (i) illustrates these shortcomings, (ii) introduces a dimensionless number quantifying the induced drag of aircraft, and (iii) proposes anfor lift, drag, and induced drag and applies it to evaluate the aerodynamics of the canard aircraft, the dual rotors of the hoveringMars helicopter, and the composite lifting system (wing plus cylinders in Magnus effect) of a YOV-10. Part II of this article applies this aerodynamic equation of state to the flapping flight of hovering and forward-flying insects. Part III applies the aerodynamic equation of state to some well-trodden cases in fluid mechanics found in fluid-mechanics textbooks.

Burgers, Phillip

Aerodynamic Drag of Road Vehicles in Close Lateral Proximity

2023-01-0952

04/11/2023

Aerodynamic interaction between vehicles on a roadway can modify the fuel use and greenhouse gas emissions of the vehicle relative to their performance under isolated, uniform-wind conditions. A comprehensive wind-tunnel study was undertaken to examine changes to the aerodynamic drag experienced by vehicles in close proximity, in adjacent lanes. Wind-load measurements were conducted for two general configurations: 15%-scale testing with light-duty-vehicle (LDV) models, and 6.7%-scale testing with a heavy-duty vehicle (HDV) model. For the LDV study, a DrivAer model was tested with a proximate AeroSUV model or an Ahmed model at lateral distances representing 75%, 100%, and 125% of a typical highway lane spacing, and for longitudinal distances up to 2 vehicle lengths forward and back. Commensurate measurements were conducted for the AeroSUV model with the proximate DrivAer or Ahmed model. For the HDV study, a tractor-trailer model was tested with a single or combination of adjacent-lane

McAuliffe, Brian, Barber, Hali

Aerodynamics of Landing Maneuvering of an Unmanned Aerial Vehicle in Close Proximity to a Ground Vehicle

2023-01-0118

04/11/2023

Autonomous takeoff and landing maneuvers of an unmanned aerial vehicle (UAV) from/on a moving ground vehicle (GV) have been an area of active research for the past several years. For military missions requiring repeated flight operations of the UAV, precise landing ability is important for autonomous docking into a recharging station, since such stations are often mounted on a ground vehicle. The development of precise and efficient control algorithms for this autonomous maneuvering has two key challenges; one is related to flight aerodynamics and the other is related to a precise detection of the landing zone. The aerodynamic challenges include understanding the complex interaction of the flows over the UAV and GV, potential ground effects at the proximity of the landing surface, and the impact of the variations in the surrounding wind flow and ambient conditions. While a large body of work in this area can be found on the control aspect of the UAV landing and takeoff maneuvers

Uddin, Mesbah, Nichols, Spencer, Hahn, Cortney, Misar, Adit, Desai, Shishir, Tison, Nathan, Korivi, Vamshi

Aerodynamic Investigation by Computational Fluid Dynamics to Exterior Design Modifications in a Simplified Bus Model

2023-01-5003

01/04/2023

Abstract Exterior design modifications have crucial importance on vehicle aerodynamics. Therefore, it makes one of the key parameters to achieve to reduce the fuel consumption in diesel-, CNG-, and hybrid-powered engines and increase the range of electric vehicles (EVs). The slightest change in the vehicle exterior design can directly affect the vehicle aerodynamics. Thus, four different parameters (front windshield angle, front diffuser angle, rear diffuser angle, and fillet [bending] on the rear and front top) are reviewed on a conceptual 12 m long bus which is to be designed at Anadolu Isuzu. Computational fluid dynamics (CFD) simulations become a source for comparative evaluations in these studies. Simulations are carried out for all different models with a realizable k-epsilon turbulence model and enhanced wall treatment wall function. In conclusion, a positive aerodynamic effect is observed with parameters that are the windshield, front diffuser angle, and fillet on the rear and

Özcan, Onur, Yıldız, Alp Eren

Aerodynamic Investigation by Computational Fluid Dynamics to Exterior Design Modifications in a Simplified Bus Model

2023-01-5003-TEST-REC01/04/2023

Özcan, Onur, Yıldız, Alp Eren

Aerodynamic Investigation by Computational Fluid Dynamics to Exterior Design Modifications in a Simplified Bus Model

2023-19-500301/04/2023

Exterior design modifications have crucial importance on vehicle aerodynamics. Therefore, it makes one of the key parameters to achieve to reduce the fuel consumption in diesel-, CNG-, and hybrid-powered engines and increase the range of electric vehicles (EVs). The slightest change in the vehicle exterior design can directly affect the vehicle aerodynamics. Thus, four different parameters (front windshield angle, front diffuser angle, rear diffuser angle, and fillet [bending] on the rear and front top) are reviewed on a conceptual 12 m long bus which is to be designed at Anadolu Isuzu. Computational fluid dynamics (CFD) simulations become a source for comparative evaluations in these studies. Simulations are carried out for all different models with a realizable k-epsilon turbulence model and enhanced wall treatment wall function. In conclusion, a positive aerodynamic effect is observed with parameters that are the windshield, front diffuser angle, and fillet on the rear and front top

Özcan, Onur, Yıldız, Alp Eren

Numerical Drag and Lift Predictions of Transport Aircrafts

2022-26-118605/26/2022

Accurate estimation of drag and lift during take-off/landing and flight of an aircraft is critical in improving its performance. The flow separation and aerodynamic forces estimation using a CFD simulation are very sensitive to numerical methods, types of grid, turbulence models and other numerical treatments. In this paper, results from the simulations of two aircraft models using a RANS based CFD software, SimericsMP+ are presented. One set of simulations are performed on a DLR-F6 model at conditions of 0.75 Mach number and 3.0e6 Reynolds number as provided in the 2nd AIAA CFD Drag Prediction Workshop. The flow behavior over a range of angle of attack during the flight condition at transonic speed is simulated for Wing Body Nacelle Pylon (WBNP) configuration of DLR-F6 model. The second set of simulations are performed on JAXA high-lift configuration Standard Model (JSM) with nacelle-off configuration. These simulations are performed for high-lift conditions of 0.172 Mach number and

Godavarthi, Raghu Vamsee, Wang, Junfeng, Maiti, Dipak

An Effective Design of Micro Tesla Valve as a Passive Mixer in Microfluidics Channels

2022-26-117805/26/2022

Mixing fluids is one of the major challenges in microfluidics. Normally, the mixing process is done by diffusion rather than turbulence, which makes it very slow due to low Reynolds number (Re) flow in the range of 0.1 to1. Owing to this behaviour, ineffective mixing occurs when two miscible liquids are mixed purely by diffusion which requires longer striation lengths and therefore longer microfluidic channels along with lengthy mixing time. Homogeneous mixing of solute and solvent is important for providing consistent chemical and biological reactions in µTAS.In this study, we develop a passive mixer that provides efficient mixing using micro tesla valves which allows the flow of liquids in the forward and reverse directions to analyse the formed vortices, turbulent intense areas, Reynolds number, and pressure using Ansys fluent workbench. An optimum design has been arrived by varying the number of cells from 1 to 5 in series and realization is done by excimer laser micromachining.

Singh, Deepak, Sankar PhD, Ravi

Design and Parametric Investigations on Various Propellers for Nature Inspired Unmanned Amphibious Vehicle

2022-26-117405/26/2022

Unmanned Amphibious Vehicle (UAV) is an integrative working environments based vehicle, which doesn’t allocate the place for onboard pilots. Mostly, unmanned amphibians have been controlled through pre-provided algorithms in the predestined paths. Aerodynamic and hydrodynamic working conditions are the compositions of aforesaid integrative environments, wherein the possible lifespan affecting failure of UAV may chance to happen in a high manner. Thus, the multidisciplinary investigation on UAV and it's every component needs to be done in order to pick the suitable UAV parts for both missions executing conditions. This work deals the comprehensive computational investigations on a different number of blades equipped propellers for the proposed cum nature-inspired UAV under aerodynamic and hydrodynamic loading conditions. Three different propellers are uniquely constructed based on the aerodynamic environment reference with the guidance of analytical formulae and thereafter modeling

R, Vijayanandh, Mathaiyan, Vijayakumar, Raji, Arul Prakash, Madasamy, Senthil Kumar, Gnanasekaran, Raj Kumar

The Short-flight Alternative

22AVEP04_0804/01/2022

The Budget Airline Car is an EV alt-shuttle seating six adults, with luggage storage in each door. Short-haul airline flights can be a great convenience for travelers, but they produce more CO2 emissions - about 250 g/km per person - than any other form of passenger transportation, including compact EVs and electric trains. That's about 25% more emissions than long-haul flights, because short-hop flying uses proportionately more fuel at takeoff and landing. Could an automotive alternative offer a solution? That is what Car Design Research (CDR), a U.K.-based consultancy, set out to investigate, working with design associates Yichen Shu in China and Aditya Jangid in India. The resulting concept is the Budget Airline Car, one of six new passenger-vehicle types that CDR director Sam Livingston and his team feel would be enabled by new mobility technologies.

Kendall, John

An Estimation of the Effect of Turbulence from the Natural Wind and Traffic on the Cycle-Averaged-Drag Coefficient.

2022-01-107603/29/2022

A drag coefficient, which is representative of the drag of a car undergoing a particular drive cycle, known as the cycle-averaged-drag coefficient, has been previously developed. It was derived for different drive cycles using mean values for the natural wind. It assumed terrain dependent wind velocities based on the Weibull function, equi-probable wind direction and shear effects. It did not, however, include any effects of turbulence in the natural wind. Some recent research using active vanes in the wind tunnel to generate turbulence has suggested that the effect on drag can be evaluated from the quasi steady wind inputs. On this basis the effect of natural wind turbulence on the aerodynamic drag of a typical car has been obtained as a function of car velocity and both wind velocity and direction. For a particular combination of car and wind velocity the additional effects of turbulence are very sensitive to the wind angle and on the shape of the drag curve with yaw angle. The wind

Howell, Jeff, Passmore, Martin

New Metrics for Quantifying the Energy Efficiency of Platoons in the Presence of Disturbances

2022-01-064503/29/2022

Due to aerodynamic drag reduction, vehicles have shown significant fuel savings while platooning in close succession. However, when circumstances force active deceleration to maintain the platoon, such as vehicle cut-ins or grade changes, the aerodynamic efficiency benefits may be undermined. In this work, the influence of active deceleration on platooning dynamics is investigated using over 400 hours of experimental data from PID-controlled and NMPC-controlled vehicle platoons. The test vehicles are Class 8 line-haul tractors with dry vans and various powertrain configurations. Using J1939 CAN data and GPS-estimated grade profiles, off-throttle data is isolated and longitudinal acceleration is estimated as a function of grade using Kalman filtering. Efficiency losses are analyzed as a function of active deceleration and analyzed to describe the effects of grade and cut-ins on platooning fuel economy. Finally, new metrics are proposed to analyze the efficiency of platoons that

Stegner, Evan, Snitzer, Philip, Bevly, David M., Hoffman, Mark

Transient car aerodynamics during an overtaking maneuver: a wind-tunnel flow simulation study

2022-01-107503/29/2022

An overtaking process realized in a wind tunnel, implying a BMW car model passing a correspondingly designed truck model (with both vehicles being down-scaled according to 1:2.5), has been investigated computationally by applying the PANS (Partially-averaged Navier-Stokes) approach representing a scale-resolving hybrid RANS/LES (Reynolds-averaged Navier-Stokes / Large-eddy Simulation) model (Basara et al.; AIAA Journal 42(12), 2011). A complementary study including the flow past an isolated BMW car model has been preliminary performed. The characteristic car-relevant flow Reynolds number, based on the axis-center distance and air velocity (of 140 km/h) corresponds to 3 million. The present overtaking maneuver, referred to as a “quasi-stationary” sequence, has been realized by considering eight distinct positions the car model takes relative to the truck configuration. Accordingly, a complete overtaking event accounting for the car positions corresponding to the car approaching the

Kutej, Lukas, Basara, Branislav, Tropea, Cameron, Hussong, Jeanette, Jakirlic, Suad

An Investigation of Aerodynamic Characteristics of Three Bluff Bodies in Close Longitudinal Proximity – Part 3: Influence on Lift

2022-01-107103/29/2022

The aerodynamic effects of bodies in close proximity continues to be an interest for those involved in aeronautical, automotive and civil engineering together with those involved in sports such as cycling, motor racing and sailing. For passenger cars, research in the USA published in the 1980s had considered travelling in close proximity, termed “platooning”, as a means for reducing congestion. But the aerodynamic drag reduction and fuel-savings found in associated wind tunnel tests and road-trials became the focus of further investigations. Although practical applications were not originally pursued, the recent development of control systems for connected and autonomous vehicles has provided the opportunity for platooning to be considered again within future traffic management systems. Thus while the focus of automotive work to date has been the potential for the reduction in total aerodynamic drag, the associated changes in aerodynamic lift which might influence the characteristics

Le Good, Geoffrey, Self, Matthew, Boardman, Peter, Resnick, Max, Cirstea, Remus

On-road Aerodynamic Measurement Techniques

2022-01-109603/29/2022

The development of car shape to provide optimal aerodynamic behaviour is typically an iterative process involving test and development. Two main test and development methods are used: wind tunnel testing (of both models and full-size cars) and Computational Fluid Dynamic (CFD) modelling. However, especially for development teams working on a small budget, there are problems with both approaches. Wind tunnel testing of full-size cars is extremely expensive. In addition, access may be problematic, especially for longer periods of testing. To be accurate, wind tunnel testing of models requires a high degree of model fidelity and appropriate wind tunnel conditions to avoid adverse Reynolds Number effects. CFD modelling, while very valuable, varies widely in quality and is always proved through physical testing. Another approach, covered in this paper, is to carry out aerodynamic testing on the road. For example, car aerodynamic drag is normally reduced if areas of separated flow along the

Edgar, Julian

An Investigation of Aerodynamic Characteristics of Two Bluff Bodies in Close Longitudinal Proximity – Sensitivity to Front-End Geometry

2022-01-109203/29/2022

With an increasing focus on the reduction of greenhouse gases by transport industries and the continued development of connected and autonomous vehicle systems, the potential for aerodynamic drag reduction by means of managed systems of vehicles travelling in close-proximity, termed “platooning”, has continued as topic for research. For commercial vehicles the principle variable for drag reduction has been the inter-vehicle spacing since, in effect, the constituents of platoons are of similar geometry. Early-work in passenger car platooning was also conducted with homogeneous platoons, but more recently the use of systematic changes in upper-body geometry has provided a further variable in the assessment of platooning characteristics. The work shown in this paper adds to investigations illustrated in SAE Papers 2019-01-0659 and 2021-01-0952 using the Windsor model with interchangeable backlight angle geometry. For this investigation a new add-on geometry to the nose was introduced to

MacAskill, James, Le Good, Geoffrey, Cirstea, Remus

The Effect of Unsteady Incident Flow on Drag Measurements for Different Vehicle Geometries in an Open Jet Wind Tunnel

2022-01-109003/29/2022

Automotive engineers use the wind tunnel to improve a vehicle’s aerodynamic properties on the road. However, a car driving on the road does not experience the steady-state, uniform flow characteristic of the wind tunnel. Wind, terrain and traffic all cause the flow experienced by the vehicle to be highly transient. Therefore, it is imperative to understand the effects of unsteady flow on the forces the vehicle experiences. To this end, the FKFS swing® installed in the University of Stuttgart’s model scale wind tunnel was used to create 36 different incident flow signals with time-resolved yaw angles. The cD values of five different 25% vehicle models, each with a notchback and a squareback configuration, were measured while under the influence of the aforementioned signals. The vehicle models were chosen to ensure a variety of different geometries, but at the same time also to enable isolated comparison of specific geometric properties. All drag measurements were corrected using the

Fei, Xiao, Kuthada, Timo, Wagner, Andreas, Wiedemann, Jochen

Study and Analysis of External Drag Reduction Methods for Tractor-Trailer Trucks using 3D CFD

2022-01-109303/29/2022

Heavy vehicles play a huge role in the national economy of a country and are responsible for the transportation of a major portion of goods across the terrain. In the United States alone, over 85% of the total value of goods are transported with the help of heavy vehicles. Despite the heavy reliance, these vehicles are not fuel-efficient and more than 40% of the engine’s power production is utilized in overcoming the vehicle aerodynamic drag at highway speeds. The present work explores drag reduction methods that could be used as an external aid for cargo trailer trucks. The paper focuses on 3D CFD analysis of different boat-tail designs that could be used to reduce aerodynamic drag on trailers. The boat tails analysed has been optimised in coherence with standard legal norms for European and US highways. It has been found and established that a truncated boat tail works as a better drag reduction measure than a full or completely inflated boat tail. The commercial code of Simerics MP

Varshney, Anchal, Khandagale, Vitthal, Saha, Rohit

The Proper Orthogonal and Dynamic Mode Decomposition of wake behind a Fastback DrivAer Model

2022-01-108603/29/2022

The aerodynamic design optimization of a ground vehicle highly depends on the wake region behind it. Vehicle's wake and its instability have a major contribution to the drag, lift, and side forces experienced by the vehicle. In this paper, we investigate numerically the dynamic characteristics of wake downstream of a realistic generic car model, DrivAer, at a Reynolds number Re=4.87E06. Two methods, Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) are applied to symmetric and asymmetric 2D planes at y=0 and 0.5 H to decompose the unsteady wake to its major dynamic modes. We simulated the flow field using the turbulence model URANS/IDDES then applied POD and DMD on streamwise and spanwise velocity components and the pressure fields. Wake dynamic mode analysis enables us to capture different modes and their contributions to the kinetic energy distribution within the region of interest. For DrivAer geometry, at high Reynolds number, we observed quasi-steady wake

Ahani, Hamed, Uddin, Mesbah, Nielsen, Jonas

Aerodynamic drag and downforce of a sport motorcycle

2022-01-107303/29/2022

The aerodynamic drag and lift of a sport-motorcycle was investigated in a full-scale and in a 1/6th scale wind tunnel tests. The results show the large vertical load transfer to the rear wheel as vehicle’s speed increases. Consequently, several simple dive and splitter-plates were tested to increase the aerodynamic downforce. These devices were added at a relatively low position on the bodywork in order to avoid adverse handling effects while leaning in turns. This study shows the level of downforce that can be generated by simple add-ons without major alterations to the bodywork. Consequently, for higher levels of aerodynamic downforce, larger underbody surfaces or wings are needed.

Katz, Joseph

Effect of Aero Covers on Underfloor Wind Noise; Conclusions from a Wind Tunnel Validated, Aero-Vibro-Acoustic Model

2022-01-036703/29/2022

Low frequency interior wind noise is typically dominated by underfloor flow noise. The source mechanisms are fluctuating surface pressure loading from both turbulence and acoustic field levels developed in the semi-reverberant cavity between floor and road. Previous studies have used computation fluid dynamics (CFD) to estimate the aero-acoustic loading applied to a vibro-acoustic model, which is then used to predict the transmitted interior wind noise. This paper reports a new perspective in two respects. First it uses sophisticated surface pressure microphone arrays to directly measure the underfloor aero-acoustic loading in the wind tunnel. Second, it considers two different underfloor aerodynamic configurations – with and without lightweight aero cover panels, which are installed primarily to reduce aerodynamic drag. Results are presented showing the relative contributions of turbulence versus acoustic sources and demonstrating validation of the aero-vibro-acoustic model for

Terakado, Susumu, Bremner, Paul

Design Optimization of Bicycle Wheel Hub Assembly for Automotive Applications

2022-01-030503/29/2022

The diminutive rolling resistance and wheel bearing drag characteristics of a bicycle wheel assembly makes it a lucrative choice of component in numerous 3-wheeled (3W) and 4-wheeled (4W) automotive applications. However, when a bicycle wheel is subjected to the loads encountered in such applications, complications pertaining to strength, durability and, performance are encountered. Since a bicycle wheel is intended to be arrested at either end of its axle, cantilever loading of the component as practiced in automotive applications diminishes the ability of the spindle to withstand longitudinal, and vertical forces encountered. Furthermore, while cornering on a bicycle, the maneuver of leaning in a corner significantly reduces the lateral stiffness requirement of the hub flanges. Therefore generic hub assemblies are designed without accounting for the action of lateral forces that are experienced at the hub with the wheel held vertical. Since most bicycle wheel assemblies are designed

Chakraborty, Apurva, R, Shreyas, Kanhai, Palash

Aerodynamic study of the different spoiler section design used in formula-SAE cars

2021-28-018110/01/2021

Aerodynamics of a car plays a very important role in a racing car. That is why many race cars are designed to take advantage of aerodynamics. Improvement cornering speed in the race car is achieved through increase in the downforce on the tire. Spoilers (inverted wings) are used for increasing the downforce but this increases the drag too. The performance of a racing car depends on both the downforce and drag, requiring good compromise between these two forces. In this paper, different airfoils which are used for building front and rear spoiler of the race car are analyzed. NACA 0012 is analyzed at 0° angle of attack the front spoiler design is made on the basis of the result with the analysis of S1223 (s1223-il) and GOE304 at 10° and 17° . Modeling of a wing is has been done in Solid work and CFD analysis using ANSYS software. Keywords: Aerodynamics, ANSYS, CFD analysis, Front and rear wing, spoiler.

Patil, Shrikant, Bhaskara Rao, Lokavarapu

Influence of Tyre Rolling Resistance and Operational Parameters on Vehicle Fuel Efficiency

2021-26-050309/22/2021

There has been a persistent demand for Vehicle fuel efficiency improvement, mainly due to ever-increasing fuel price and imposition of stricter regulatory norms to curb greenhouse gas emissions. Factors like driving style, vehicle weight, engine, tyre, aerodynamics, weather conditions, etc. affect fuel efficiency. This study focuses on the impact of certain sub-parameters like tyre construction, tyre wear, inflation pressure and driver behavior to establish a correlation between the Rolling Resistance Coefficient (RRC) of a tyre and the fuel efficiency of the vehicle. Tyres with contrasting RRC are considered with multiple drivers and driving conditions while measuring Fuel efficiency using test cycles defined as Constant Speed Test (CST), Mixed Cycle Test (MCT) and Public Road Test (PRT). Fuel consumption sensitivity to driving behavior or driving aggressiveness varies even within expert drivers [1][2]. Reduction in Non-Skid Depth due to tyre wear adversely affects its properties

TOMER, AVINASH, Chepyala, Shiva Kumar Reddy, Mukhopadhyay, Rabindra, Ghosh, Prasenjit

Coastdown Road Load Coefficients of Passenger Vehicles – Variation Analysis and its Correlation with Temperature

2021-26-048709/22/2021

Road Load parameters (rolling resistance & aerodynamic drag) of a vehicle have strong impact on overall Vehicle Emissions & Fuel Economy. The road load coefficients are simulated on chassis dynamometer to carryout emission & fuel economy measurement and are hence required to be found beforehand. A realistic measure of road load parameters can be obtained by conducting a coastdown test. Coastdown test results are hugely impacted by various environmental parameters like ambient temperature, atmospheric pressure, wind speed etc. Though performed in standard boundary conditions, results of multiple tests performed on a vehicle vary from one another due to variations in the mentioned environmental parameters over & above standard test to test variation. This paper aims at studying the variation in test results due to ambient temperature as one of the parameters responsible. For this study, road load coefficients from more than 100 coastdown tests conducted on oval test track for almost 30

Kuhar, Saurabhh, Pattalwar, Ashutosh, Gupta, Parveen

Aerodynamic performance prediction using a novel approach of Ansys Mosaic mesh & revolutionary GEKO turbulence model, and application of Adjoint Solver for aerodynamic Optimisation of a car

2021-26-035309/22/2021

In the present scenario, wherein the cost of transportation is continuously increasing, achieving optimum fuel efficiency is key area of focus for many Automotive OEMs. Aerodynamic drag is prominent form of resistance any vehicle encounters while it is in motion, and this particularly increases at higher speeds and overtakes all other forms of resistive forces acting on vehicle. Hence, predicting and improving aerodynamic performance of a car forms a very important aspect in overall product design cycle. Engineers and designers around the world try different methods for predicting and improving the aerodynamics of a car, including rigorous wind tunnel & test track testing. However, in our current paper, we will be discussing a novel approach to predict and improve the aerodynamics drag for an academic test vehicle (Ford-Ka) model. The paper will contain two sections, first section will showcase usage of a new meshing technology, Mosaic Mesh, and a revolutionary breakthrough turbulence

Patil, Tushar, Patil, Vivek

Aero drag improvement study on large commercial vehicles using CFD lead approach

2021-26-042409/22/2021

Nowadays, E- commerce and logistics business model is booming in India with road transport as a major mode of delivery system using containers. As competition in such business are on rise, different ways of improving profit margins are been continuously evolved. One such scenario is to look at reducing transportation cost while reducing fuel consumption. Traditionally, aero dynamics of commercial vehicles have never been in focus during their product development although literature shows major part of total fuel energy is consumed in overcoming aerodynamic drag at and above 60 kmph in case of large commercial vehicle. Hence improving vehicle exterior aerodynamic performance gives opportunity to reduce fuel consumption and thereby business profitability. Also byproduct of this improvement is reduced emissions and meeting regulatory requirements. To bring this into reality, vehicle manufacturers are looking at different opportunities to reduce aero drag and one such method that are been

ANWAR, FAISAL, Gulavani, Rohan Arun, Chalipat, Sujit, Jadhav, Satish

Aerodynamic approach on enhancing the downforce in a self-powered Electric Vehicle

2021-26-035809/22/2021

With the world moving towards sustainable energy, the importance of Electric Vehicles (EV) has gained huge momentum. However merely moving with a rechargeable structure has put forward many challenges and the quest for a better alternative to power the vehicle electrically remains constant. Researchers across the world are looking forward to how the vehicle can be made self-powered. The study aims at proposing a self-powered and aerodynamically robust design of an EV. The enhanced downforce and reduced air drag were analyzed using Computational Fluid Dynamics (CFD). The vehicle design is proposed using the principles of bio-mimicry following the standard procedures of transportation design. Speedform (a primitive form of the vehicle design generally considered as the visual vocabulary for transportation design) was developed computationally using AutoCAD. To enhance the Aerodynamic robustness of the vehicle, unique Aerodynamic Spoilers inspired by Venturi tunnels of Le Mans Sportscar

Moon, Rohini Ramrao, Prajapati, Shivam, MISHRA, PRAYAG RAJ

Speed Planning System for Commercial Vehicles in Mountainous Areas

2021-01-0126-TEST-REC04/06/2021

There are a large number of curves and slopes in the mountainous areas. Unreasonable acceleration and deceleration in these areas will increase the burden of the brake system and the fuel consumption of the vehicle. The main purpose of this paper is to introduce a speed planning and promotion system for commercial vehicles in mountainous areas. The wind, slope, curve, engine brake, and rolling resistances are analyzed to establish the thermal model of the brake system. Based on the thermal model, the safe speed of the brake system is acquired. The maximum safe speed on the turning section is generated by the vehicle dynamic model. And the economic speed is calculated according to the fuel consumption model. The planning speed is provided based on these models. This system can guide the driver to handle the vehicle speed more reasonably. According to the simulation, compared to cruise control, speed planning can save fuel consumption at a mean value of 9.13% in typical mountainous areas

Peng, Dengzhi, Fang, Kekui, Tian, Zhongpeng, Zhang, Yuxiao, Tan, Gangfeng

Speed Planning System for Commercial Vehicles in Mountainous Areas

2021-01-0126

04/06/2021

Peng, Dengzhi, Fang, Kekui, Tian, Zhongpeng, Zhang, Yuxiao, Tan, Gangfeng

Near-to-Far Wake Characteristics of Road Vehicles Part 2: Influence of Cross Winds and Free-Stream Turbulence

2021-01-094904/06/2021

Conventional assessments of the aerodynamic performance of ground vehicles have, to date, been considered in the context of a vehicle that encounters a uniform wind field in the absence of surrounding traffic. Recent vehicle-platooning studies have revealed measurable fuel savings when following other vehicles at inter-vehicle distances experienced in every-day traffic. These energy savings have been attributed in large part to the air-wakes of the leading vehicles. This set of three papers documents a study to examine the near-to-far regions of ground-vehicle wakes (one to ten vehicle lengths), in the context of their potential influence on other vehicles. Part two of this three-part paper documents the influence of the ambient winds on the development of the wake behind a vehicle. A series of scaled-model wind-tunnel measurements, supplemented by some high-fidelity numerical simulations, based on a Lattice-Boltzmann approach, are presented to examine the effects cross-wind magnitude

McAuliffe, Brian, Sowmianarayanan, Bhargav, Barber, Hali

Near-to-Far Wake Characteristics of Road Vehicles Part 1: Influence of Ground Motion and Vehicle Shape

2021-01-095704/06/2021

Conventional assessments of the aerodynamic performance of ground vehicles have, to date, been considered in the context of a vehicle that encounters a uniform wind field in the absence of surrounding traffic. Recent vehicle-platooning studies have revealed measurable fuel savings when following other vehicles at inter-vehicle distances experienced in every-day traffic. These energy savings have been attributed in large part to the air-wakes of the leading vehicles. This set of three papers documents a study to examine the near-to-far regions of ground-vehicle wakes (one to ten vehicle lengths), in the context of their potential influence on other vehicles. Part one of this three-part paper documents principally the influence of vehicle shape on the development of its wake. A series of high-fidelity numerical simulations, based on a Lattice-Boltzmann approach, and a series of scaled-model wind-tunnel measurements are presented to examine the effects of four types of vehicles: a sedan

McAuliffe, Brian, Sowmianarayanan, Bhargav, Barber, Hali

Rolling Resistance Measurement Procedure for Highway Truck and Bus Tires

J1379_202011 (Current)

11/12/2020

This recommended practice applies to the laboratory measurement of the rolling resistance of pneumatic tires designed primarily for use on trucks and buses in normal highway service, as defined by the Tire and Rim Association, Inc. (TRA); it does not include light truck tires (designated LT). The procedure applies only to straight, free-rolling tires under steady-state operation and includes the following three basic methods:

Truck and Bus Tire Committee

The Measurement of Highway Truck and Bus Tire Rolling Resistance

J1380_202011 (Current)

11/09/2020

The force, torque, and energy methods of measurement are all in common use and should yield the same test results. Effects of steering, traction, and non steady-state tire operations are excluded from the recommended practice because they are still in the research stage. Methods of correcting laboratory data to road conditions are being developed.

Truck and Bus Tire Committee

Tire pressure's impact on EV driving range

20AUTP11_0311/01/2020

A new study shows that tighter control of tire-pressure loss can lead to marked improvement in electric-vehicle efficiency. Electric-vehicle development teams have made great advances in improving vehicle range, mitigating “range anxiety” for the end customer. While much focus has been on advances in battery technology, controls and vehicle aerodynamics, EV driving range also is significantly affected by tires. Energy-inefficient tire construction, sub-optimal inflation and other factors can adversely impact EV range. Tires lose a certain amount of air on a continuous basis. An underinflated tire is less stiff and its deformation is much higher, leading to a larger amount of heat dissipation and ultimately higher rolling resistance and poor range efficiency.

Tang, Lamei, Wei, Sheng, Valentage, Jeffrey, Li, Zheng, Nair, Sujith

Instrumentation for Fabrication and Testing of High-Speed Single-Rotor and Compound-Rotor Systems

TBMG-3788010/01/2020

Precision data acquisition is required to generate a comprehensive set of measurements of the blade surface pressures, pitch link loads, hub loads, rotor wakes and performance of high-speed single-rotor and compound-rotor systems to support the development of next-generation rotorcraft, such as envisioned in the Joint Multi-Role (JMR) rotorcraft program. These data are crucial to validate advanced CFD tools, as well as gain improved understanding of the fundamental physics in high advance ratio flight conditions.

A Priori Analysis of Acoustic Source Terms from Large-Eddy Simulation in Turbulent Pipe Flow

2020-01-151806/03/2020

The absence of combustion engine noise pushes increasingly attention to the sound generation from other, even much weaker, sources in the acoustic design of electric vehicles. The present work focusses on the numerical computation of flow induced noise, typically emerging in components of flow guiding devices in electro-mobile applications. The method of Large-Eddy Simulation (LES) represents a powerful technique for capturing most part of the turbulent fluctuating motion, which qualifies this approach as a highly reliable candidate for providing a sufficiently accurate level of description of the flow induced generation of sound. Considering the generic test configuration of turbulent pipe flow, the present study investigates in particular the scope and the limits of incompressible Large-Eddy Simulation in predicting the evolution of turbulent sound sources to be supplied as source terms into acoustic analogies, which have been proposed for the computation of the acoustic pressure

Tieber, Johannes, Steiner, Helfried

Supersonic Spike Diffuser

TBMG-3682405/01/2020

The basic mode of operation for all passive supersonic diffusers is to enable a plume’s inherent power to drive the outer boundary of the exhaust jet to the diffuser wall so that the entire cross-section of the flow has a speed greater than that of sound. This allows mass removal from the area surrounding the nozzle via entrainment. The result is a low-pressure environment similar to the altitude at which the nozzle was designed to operate. Additionally, the nature of supersonic flow prevents pressure interference from the downstream environment.

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