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Impact of Wheel-Housing on Aerodynamic Drag and Effect on Energy Consumption on an Electric Bus Body

ARAI Academy-Amitabh Das, Yash Jain
Automotive Research Association of India-Mohammad Rafiq Agrewale, Kamalkishore Vora
  • Technical Paper
  • 2019-28-2394
Published 2019-11-21 by SAE International in United States
Role of wheel and underbody aerodynamics of vehicle in the formation of drag forces is detrimental to the fuel (energy) consumption during the course of operation at high velocities. This paper deals with the CFD simulation of the flow around the wheels of a bus with different wheel housing arrangements. Based on benchmarking, a model of a bus is selected and analysis is performed. The aerodynamic drag coefficient is obtained and turbulence around wheels is observed using ANSYS Fluent CFD simulation for different combinations of wheel-housing- at the front wheels, at the rear wheels and both in the front and rear wheels. The drag force is recorded and corresponding influence on energy consumption of a bus is evaluated mathematically. A comparison is drawn between energy consumption of bus body without wheel housing and bus body with wheel housing. The result shows a significant reduction in drag coefficient and fuel consumption.
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Numerical Simulation of Battery Thermal Management Systems in Electric Vehicles

Pranav Vikas, Ltd.-Bharat Kumar Nuthi, Vijayaraghavan S, D. Govindaraj
  • Technical Paper
  • 2019-28-2481
Published 2019-11-21 by SAE International in United States
Electric vehicle works on stored energy inside the batteries or cells. These units needs to be regulated by cool down or heat up to perform utmost. This temperature regulation also ensure individual battery or cell life. BCS are installed on vehicles to regulate the temperature around battery packs. To ensure maximum performance of these units, numerical simulation is performed and detailed optimization of flow rate as well as flow path into BCS is carried out. All the parts are assembled inside the unit as per defined packaging area or size. Numerical modelling (CFD) is performed to examine the flow path. Flow path is very important to examine, as BCS units consists of condenser. It is very important for condensers to perform efficiently, which means air flow should happen across it appropriately. If sufficient flow is not happening across the condenser, then performance of condensers comes down and optimum temperature around battery packs cannot be maintained. This will affect the performance of battery pack capacity as well as individual battery life. Based on results obtained from…
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Modelling for Collective Effect of Muffler Geometric Modifications and Blended Microalgae Fuel Use on Exhaust Performance of a Four-Stroke Diesel Engine: A Computational Fluid Dynamics Approach

Lovely Professional University-Sumit Kanchan, Rajesh Choudhary, Chavagani Brahmaiah
University of Kashmir-Shahid Qayoom
  • Technical Paper
  • 2019-28-2377
Published 2019-11-21 by SAE International in United States
Engine performance significantly depends on the effective exhaust of the combustion gases from the muffler. With stricter BSVI norms more efficient measures have to be adopted to reduce the levels of emissions from the exhaust to the atmosphere. Muffler along with reducing the engine noise is intended to control the back pressure as well. Back pressure change has a significant effect on muffler temperature distribution which affects the NOx emission from the exhaust. Many research communications have been made to reduce the exhaust emissions like HC, CO and CO2 from the exhaust by using different generation biofuels as an alternative fuel, yet they have confronted challenges in controlling the NOx content from the exhaust.This work presents the combined effect of Muffler geometry modifications and blended microalgal fuel on exhaust performance with an aim to reduce NOx emission form a four-stroke engine. In this exertion, the computational fluid dynamics model is developed to analyze the effect of muffler geometry modification on vital exhaust parameters of an engine. The engine is powered with a blend of chlorella…
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Heat Shield Insulation for Thermal Challenges in Automotive Exhaust System

Sharda Motor Industries, Ltd.-Sivanandi Rajadurai, Ananth S
  • Technical Paper
  • 2019-28-2539
Published 2019-11-21 by SAE International in United States
While advanced automotive system assemblies contribute greater value to automobile safety, reliability, emission/noise performance and comfort, they are also generating higher temperatures that can reduce the functionality and reliability of the system over time. Thermal management and proper insulation are extremely important and highly demanding for the functioning of BSVI and RDE vehicles. Frugal engineering is mandatory to develop heat shield in the exhaust system with minimum heat loss. Heat shield design parameters such as insulation material type, insulation material composition, insulation thickness, insulation density, air gap thickness and outer layer material are studied for their influences on skin temperature using mathematical calculation, CFD simulation and measurement. Simulation results are comparable to that of the test results within 10% deviation. The performance index is calculated using the temperature gradient between the pipe surface and the external skin temperature. The performance index increases with material insulation thickness and insulation material density. Increase in insulation thickness from 6 mm to 19 mm reduces the skin temperature from 44% to 77%. The specialty insulation material provides a high…
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Improving the Modelling of Dissociating Hydrogen Nozzles

SAE International Journal of Aerospace

Prince Mohammad Bin Fahd University, Saudi Arabia Ton Duc Thang University, Vietnam-Alberto Boretti
  • Journal Article
  • 01-12-02-0006
Published 2019-11-21 by SAE International in United States
While the design of nozzles for diatomic gases is very well established and covered by published works, the case of a diatomic gas dissociating to monatomic along a nozzle is a novel subject that needs a proper mathematical description. These novel studies are relevant to the definition of nozzles for gas-core Nuclear Thermal Rockets (NTR) that are receiving increased attention for the potential advantages they may deliver versus current generation rockets. The article thus reviews the design of the nozzles of gas-core NTR that use hydrogen as the propellant. Propellant temperatures are expected to reach 9,000-15,000 K. Above 1500 K, hydrogen begins to dissociate at low pressures, and around 3000 K dissociation also occurs at high pressures. At a given temperature, the lower the gas pressure the more molecules dissociate, and H2 → H + H. The properties of the gas are a function of the mass fractions of diatomic and monatomic hydrogen x H2 and x H = 1 − x H2. Dissociation influences the molecular weight of the gas and its heat capacity,…
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1D Numerical and Experimental Investigations of an Ultralean Pre-chamber Engine

SAE International Journal of Engines

Business Unit Gasoline Powertrains FEV Europe GmbH in Aachen, Germany-Christoph Müller, Knut Habermann
Universita degli Studi di Napoli Federico II Dipartimento di Ingegneria Industriale, Italy-Vincenzo De Bellis
  • Journal Article
  • 03-13-02-0012
Published 2019-11-19 by SAE International in United States
In recent years, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigations. With this solution, in fact, it is possible to simultaneously reduce NOx raw emissions and fuel consumption due to decreased heat losses, higher thermodynamic efficiency, and enhanced knock resistance. However, the real applicability of this technique is strongly limited by the increase in cyclic variation and the occurrence of misfire, which are typical for the combustion of homogeneous lean air/fuel mixtures. The employment of a Pre-Chamber (PC), in which the combustion begins before proceeding in the main combustion chamber, has already shown the capability of significantly extending the lean-burn limit. In this work, the potential of an ultralean PC SI engine for a decisive improvement of the thermal efficiency is presented by means of numerical and experimental analyses. The SI engine is experimentally investigated with and without the employment of the PC with the aim to analyze the real gain of this innovative combustion system. For both configurations, the engine is tested at various speeds, loads, and air-fuel ratios. A…
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Development of a Novel Machine Learning Methodology for the Generation of a Gasoline Surrogate Laminar Flame Speed Database under Water Injection Engine Conditions

SAE International Journal of Fuels and Lubricants

NAIS S.r.l., Italy-Claudio Forte
University of Bologna, Italy-Leonardo Pulga, Gian Marco Bianchi, Matteo Ricci, Giulio Cazzoli
  • Journal Article
  • 04-13-01-0001
Published 2019-11-19 by SAE International in United States
The water injection is one of the technologies assessed in the development of new internal combustion engines fulfilling new emission regulation and policy on Auxiliary Emission Strategy assessment. Besides all the positive aspects about the reduction of mixture temperature at top dead center and exhaust gases temperature at turbine inlet, it is well known that the water vapor acts as a mixture diluter, thus diminishing the reactants burning rate. A common methodology employed for the Reynolds-Averaged Navier-Stokes Computational Fluid Dynamics (RANS CFD) simulation of the reciprocating internal combustion engines’ turbulent combustion relies on the flamelet approach, which requires knowledge of the Laminar Flame Speed (LFS) and thickness. Typically, these properties are calculated by means of correlation laws, but they do not keep into account the presence of water mass fraction. A more precise methodology for the definition of both the LFS and thickness is thus required. The interrogation of a previously computed look-up table of such properties during run time seems to be a suitable and more accurate method than using correlations. In order to…
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Design and Fabrication of a Formula SAE Undertray

Colorado School of Mines-Jacob Thom, Bridger Armstrong, Robin Chow, Forrest Denham, Quinn Khosla, Luke La Rocque, John Oldland, Steven Ripple, Nicholas Sammons
Published 2019-10-22 by SAE International in United States
Aerodynamic packages can provide a significant performance benefit to Formula SAE cars, but design and development of a full aerodynamics package can be time-consuming and expensive. An undertray system can provide significant aerodynamic benefits at a lower cost than a full aerodynamics package with front and rear wings. To properly design and test an undertray, a robust program of computational fluid dynamics (CFD) analysis and verification is needed. CFD analysis can be challenging, especially for large external flow problems like that of a full car. Due to this difficulty, careful meshing and setup of simulations is necessary to ensure accurate results. Much like analysis, fabrication of an aerodynamics package for a Formula SAE car is difficult. Fiberglass and carbon fiber layup processes are commonly used, but are prone to a variety of issues, and can be costly and time-consuming. Therefore, a thorough layup schedule and a careful manufacturing process is necessary. Fiberglass and carbon fiber were chosen as materials for the undertray due to their low weight relative to strength. These materials are often difficult…
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Overset Mesh-Based Computational Investigations on the Aerodynamics of a Generic Car Model in Proximity to a Side-Wall

SAE International Journal of Passenger Cars - Mechanical Systems

University of North Carolina at Charlotte, USA-Charles Patrick Bounds, Srivatsa Mallapragada, Mesbah Uddin
  • Journal Article
  • 06-12-03-0015
Published 2019-10-21 by SAE International in United States
This article discusses an approach to simulating a generic idealized car model (Ahmed body) moving in close proximity to a side-wall, using a transient Computational Fluid Dynamics (CFD) method. This phenomenon is very important in motorsports, where racing close to the safety barrier is common. Driving in close proximity to a side-wall alters the aerodynamic characteristics of the vehicle significantly; however, only a handful of published works exist in this area. Additionally, the experimental studies conducted in the past suffer from certain inadequacies, especially in terms of simulating the side-wall. This casts some uncertainty as to the relevance of these studies to the real-world problem. The present study attempts to imitate the real-world flow phenomenon by taking a nontraditional CFD approach of translating the body relative to the stationary surrounding fluid and side-wall instead of the classical method of flowing air over a stationary vehicle model. This was achieved by using a relatively new and computationally efficient meshing technique for overlapping grids called the “Overset” or “Chimera” mesh. The initial task was to accurately predict…
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Reduced-Order Modeling of Vehicle Aerodynamics via Proper Orthogonal Decomposition

SAE International Journal of Passenger Cars - Mechanical Systems

Technische Universität Braunschweig, Germany-Rolf Radespiel
Volkswagen AG, Germany-Markus Mrosek, Carsten Othmer
  • Journal Article
  • 06-12-03-0016
Published 2019-10-21 by SAE International in United States
Aerodynamic optimization of the exterior vehicle shape is a highly multidisciplinary task involving, among others, styling and aerodynamics. The often differing priorities of these two disciplines give rise to iterative loops between stylists and aerodynamicists. Reduced-order modeling (ROM) has the potential to shortcut these loops by enabling aerodynamic evaluations in real time. In this study, we aim to assess the performance of ROM via proper orthogonal decomposition (POD) for a real-life industrial test case, with focus on the achievable accuracy for the prediction of fields and aerodynamic coefficients. To that end, we create a training data set based on a six-dimensional parameterization of a Volkswagen passenger production car by computing 100 variants with Detached-Eddy simulations (DES). Based on this training data, we reduce the dimension of the solution space via POD and interpolate the base coefficients with Kriging (aka Gaussian Process Regression) for predictions of the flow field at unseen parameter combinations. The error analysis of the fields and drag coefficient predictions reveal that 100 training samples are sufficient for this six-dimensional test case in…
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