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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
To be published on 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. Keywords: Wheel-housing, Drag Coefficient, CFD Simulation, Bus, Energy consumption
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CFD Simulation on Turbulent Forced Convection of Copper Oxide (CuO) -Water Nanofluids in a Horizontal Circular Pipe

John Deere India Pvt, Ltd.-Nitin Dewangan, Nitin Kattula
  • Technical Paper
  • 2019-28-0131
To be published on 2019-10-11 by SAE International in United States
The present study provides a detailed investigation on simulation of Copper oxide nanofluids in a simple horizontal circular pipe considering turbulent forced convection, with a constant heat flux boundary condition. The simulation is carried out using three different models available in fluent viz. Newtonian single phase model, Eulerian-mixture and Eulerian-Eulerian multiphase models. The Reynold number of the flow is varied along with volume concentration of nanoparticles varying form low to high. Nanofluids rheology is studied by considering standard k-ε two equation turbulence model with enhanced wall treatment considering appropriate wall y+ values. The effective temperature dependent thermo-physical properties for nanofluids were seized from the literatures. The results from the simulation clearly showed an increase in the heat transfer characteristics with the addition of nanoparticles compared to that of base fluid alone. Eulerian-Mixture model predicted the Nusselt number near to that of the experimental results from literature.
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Increase of Compressor Performance through the Use of Microstructures

Bionic Surface Technologies GmbH-Mikel Garcia de Albeniz, Peter Adrian Leitl
RINA-Emiliano Costa, Stefano Barberis
  • Technical Paper
  • 2019-24-0239
To be published on 2019-10-07 by SAE International in United States
This paper describes how turbomachines can be optimized by simulating the effect of micro- and nanostructures suitably created over the shapes of their constituting components in order to increase the efficiency of the whole mechanical system. These structures, called riblets, consist of tiny streamwise grooved surfaces which reduce the drag in the turbulent boundary layer. Theoretical, numerical and experimental experiences give a first estimation of the impact of riblets in industrial compressors. In this case, the riblet structures reduce the aerodynamic shear stress losses. The areas of higher interest are the diffusor and the volute. It is there where the higher losses happen. The optimal size, position and effect on performance is going to be analysed. The use of such an effective numerical means may give benefits in terms of efficiency increase as well as of CO2 and noise emission reduction and, for these reasons, it also has a positive economical and societal impact in relation to mobility. The presented activities were performed in the Framework of the ReSISTant project, which was co-financed by the…
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Large Eddy Simulation of an Ignition Front in a Heavy Duty Partially Premixed Combustion Engine

Lund University-Christian Ibron, Hesameddin Fatehi, Mehdi Jangi, Xue-Song Bai
Published 2019-09-09 by SAE International in United States
In partially premixed combustion engines high octane number fuels are injected into the cylinder during the late part of the compression cycle, giving the fuel and oxidizer enough time to mix into a desirable stratified mixture. If ignited by auto-ignition such a gas composition can react in a combustion mode dominated by ignition wave propagation. 3D-CFD modeling of such a combustion mode is challenging as the rate of fuel consumption can be dependent on both mixing history and turbulence acting on the reaction wave. This paper presents a large eddy simulation (LES) study of the effects of stratification in scalar concentration (enthalpy and reactant mass fraction) due to large scale turbulence on the propagation of reaction waves in PPC combustion engines. The studied case is a closed cycle simulation of a single cylinder of a Scania D13 engine running PRF81 (81% iso-octane and 19% n-heptane). Two injection timings are investigated; start of injection at -17 CAD aTDC and -30 CAD aTDC. One-equation transported turbulence sub-grid closure is used for the unresolved momentum and scalar fluxes…
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A New Take on Porous Medium Approach for Modelling Monoliths and Other Multiple Channel Devices

Coventry University-Gianluca Padula, Jonathan Saul, Svetlana Aleksandrova, Humberto Medina, Stephen Benjamin
  • Technical Paper
  • 2019-24-0049
Published 2019-09-09 by SAE International in United States
The porous medium approach is widely used to represent high-resistance devices, such as catalysts, filters or heat exchangers. Because of its computational efficiency, it is invaluable when flow losses need to be predicted on a system level. One drawback of using the porous medium approach is the loss of detailed information downstream of the device. Correct evaluation of the turbulence downstream affects the calculation of the related properties, e.g. heat and mass transfer.The novel approach proposed in the current study is based on a modified distribution of the resistance across the porous medium, which allows to account for the single jets developing in the small channels, showing an improved prediction of the turbulence at the exit of the device, while keeping the low computational demand of the porous medium approach.The benefits and limitations of the current approach are discussed and presented by comparing the results with different numerical approaches and experiments. The flexibility of the proposed approach in terms of describing the device geometry is demonstrated via an optimisation study where the size of the…
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A Fundamental Study on Combustion Characteristics in a Pre-Chamber Type Lean Burn Natural Gas Engine

Waseda University-Masashi Tanamura, Shintaro Nakai, Mahoko Nakatsuka, Shota Taki, Kohei Ozawa, Beini Zhou, Ratnak Sok, Yasuhiro Daisho, Jin Kusaka
Published 2019-09-09 by SAE International in United States
Pre-chamber spark ignition technology can stabilize combustion and improve thermal efficiency of lean burn natural gas engines. During compression stroke, a homogeneous lean mixture is introduced into pre-chamber, which separates spark plug electrodes from turbulent flow field. After the pre-chamber mixture is ignited, the burnt jet gas is discharged through multi-hole nozzles which promotes combustion of the lean mixture in the main chamber due to turbulence caused by high speed jet and multi-points ignition. However, details mechanism in the process has not been elucidated.To design the pre-chamber geometry and to achieve stable combustion under the lean condition for such engines, it is important to understand the fundamental aspects of the combustion process. In this study, a high-speed video camera with a 306 nm band-pass filer and an image intensifier is used to visualize OH* self-luminosity in rapid compression-expansion machine experiment. The results show that the OH* self-luminosity is observed in outer edge of the jet, while the luminosity in the jet temporarily weakens because the turbulent jet is exposed to low temperature surrounding in the…
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Effects of the LES-Mode SGS Viscosity Formulation on the Hybrid URANS/LES Modeling of Turbulent Fuel Sprays

University of Rome Niccolò Cusano-Giovanni Di Ilio
University of Rome Tor Vergata-Vesselin Krastev, Gino Bella
Published 2019-09-09 by SAE International in United States
The LES hybridization of standard two-equation turbulence closures is often achieved leaving formally unchanged the turbulent viscosity expression in the URANS and LES modes of operation. Although generally convenient in terms of ease of implementation, this choice leaves some theoretical consistency questions unanswered, the most obvious being the actual meaning of the two transported turbulent scalars and their exact role in the modeled viscosity build-up. A possible remedy to this is represented by the simultaneous modification of one or both the turbulent transport equations and of the turbulent viscosity formula, for which a standard LES behavior is enforced whenever needed. The present work compares a conventional DES-based hybrid model with a consistency-enforcing modified variant for turbulent fuel spray simulation. In our case, LES-mode consistency is accomplished by excluding the second turbulent scalar quantity from the viscosity calculation. In this way, the turbulent kinetic energy acts as SGS kinetic energy and the SGS viscosity is evaluated according to the well known one-equation LES implementation. The conventional and modified hybrid models are applied to the simulation of…
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Development and Validation of SI Combustion Models for Natural-Gas Heavy-Duty Engines

Politecnico di Milano-Lorenzo Sforza, Tommaso Lucchini, Giovanni Gianetti, Gianluca D'Errico
Published 2019-09-09 by SAE International in United States
Flexible, reliable and consistent combustion models are necessary for the improvement of the next generation spark-ignition engines. Different approaches have been proposed and widely applied in the past. However, the complexity of the process involving ignition, laminar flame propagation and transition to turbulent combustion need further investigations. Purpose of this paper is to compare two different approaches describing turbulent flame propagation. The first is the one-equation flame wrinkling model by Weller, while the second is the Coherent Flamelet Model (CFM). Ignition is described by a simplified deposition model while the correlation from Herweg and Maly is used for the transition from the laminar to turbulent flame propagation. Validation of the proposed models was performed with experimental data of a natural-gas, heavy duty engine running at different operating conditions. To deeply analyze main differences between Weller and CFM models, a detailed comparison of computed and experimental data was performed in terms of cylinder pressure, heat release rate, wall heat transfer, distribution of progress variable and flame surface density.
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Torque and Pressure CFD Correlation of a Torque Converter

SAE International Journal of Passenger Cars - Mechanical Systems

Ford Motor Company, USA-Steve Frait, Ram Devendran
Michigan Technological University, USA-Edward De Jesus Rivera, Mark Woodland, Darrell Robinette, Jason Blough, Carl Anderson
  • Journal Article
  • 06-12-03-0012
Published 2019-08-22 by SAE International in United States
A torque converter was instrumented with 29 pressure transducers inside five cavities under study (impeller, turbine, stator, clutch cavity between the pressure plate and the turbine shell). A computer model was created to establish correlation with measured torque and pressure. Torque errors between test and simulation were within 5% and K-Factor and torque ratio errors within 2%. Turbulence intensity on the computer model was used to simulate test conditions representing transmission low and high line pressure settings. When turbulence intensity was set to 5%, pressure simulation root mean square errors were within 11%-15% for the high line pressure setting and up to 34% for low line pressure setting. When turbulence intensity was increased to 50% for the low line pressure settings, a 6% reduced root mean square error in the pressure simulations was seen. For all pressure settings, cavities closer to the converter inlet required a 5% turbulence intensity while the cavities inside or near the torus were better suited with 50% turbulence intensity levels.
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Modelling and Numerical Simulation of Dual Fuel Lean Flames Using Local Burning Velocity and Critical Chemical Timescale

SAE International Journal of Engines

Alstom, Switzerland-Naresh K. Aluri
Kingston University, UK-Siva Muppala
  • Journal Article
  • 03-12-04-0025
Published 2019-07-02 by SAE International in United States
Addition of hydrogen to hydrocarbons in premixed turbulent combustion is of technological interest due to their increased reactivity, flame stability and extended lean extinction limits. However, such flames are a challenge to reaction modelling, especially as the strong preferential diffusion effects modify the physical processes, which are of importance even for highly turbulent high-pressure conditions. In the present work, Reynolds-averaged Navier-Stokes (RANS) modelling is carried out to investigate pressure and hydrogen content on methane/hydrogen/air flames. For this purpose, four different subclosures, used in conjunction with an algebraic reaction model, are compared with two independent sets of experimental data: (1) Orléans data consists of pressures up to 9 bar, with addition of hydrogen content by up to 20% in hydrogen/methane mixture, for moderate turbulence intensities. 2) The Paul Scherrer Institute data includes same fuels with higher volume proportion of hydrogen (40%), at much higher turbulent intensities at 5 bar. The first model Model I is based solely on the increased reactivity of the hydrogen/methane mixture under laminar conditions. It shows that the increase of unstretched laminar…
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