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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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Winglet Design and Analysis for Cessna 152 - A Numerical Study

SRM Institute of Science and Technology-Vivek Saini, Nagarajan Sunil Bhargav, Yallur Mohiddinsha, Sundararaj Senthilkumar
Published 2019-10-11 by SAE International in United States
During flight an emergent circulatory flow pattern named vortex is observed at wing tips producing induced drag. An approach to reduce this effect is by implementing winglets. Winglets are small wing-like lifting surfaces, fitted at the tip of some wings, usually with the objective of decreasing trailing vortex drag and thereby increasing the aerodynamic efficiency of the wing. The aim of the project is to design and analyze the effect of winglets for Cessna 152 by varying the cant angle and sweep angle. This model has been selected since it provides a good choice for Pilots first airplane. A baseline wing model was designed in CATIA V5, correspondingly wings with winglet models were designed with a fixed taper ratio of 0.2 and different cant and sweep angles. The lift to drag ratio is evaluated at different angles of attack by varying winglet design parameters. Different wing configurations with various Cant and Sweep angles were analyzed at sea level conditions using K-ω SST turbulent model in ANSYS FLUENT and best winglet with desired characteristics for optimum…
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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
Published 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
Published 2019-10-07 by SAE International in United States
Turbomachinery efficiency is becoming more and more relevant in order to reduce fuel consumption and mechanical wear of machines at the purpose of increasing their environmental sustainability and reliability. Optimized material identification and design is therefore of paramount importance. This paper describes how turbomachines can be optimized thanks to the effect of microstructures suitably created over the shapes of their constituting components in order to increase the overall efficiency via a simple coating solution. These structures, called riblets, consist of tiny streamwise grooved surfaces which are such to reduce drag in the turbulent boundary layer. Theoretical, numerical and experimental experiences gave 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 diffuser and the volute, where the higher losses happen. The optimal size, position and effect on performance were analysed via simulation. The use of such an effective numerical means may give a precise evaluation about benefits in terms of efficiency increase as well as…
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Green’s Function Extraction from Atmospheric Acoustic Propagation

  • Magazine Article
  • TBMG-35363
Published 2019-10-01 by Tech Briefs Media Group in United States

Acoustic waves propagating in the atmosphere may undergo many effects including refraction by temperature and wind velocity gradients, scattering by atmospheric turbulence, absorption by the atmosphere (fluid), diffraction by terrain features, and absorption and reflection by a porous ground. As a result, there may be insonification in acoustic shadow zones, amplitude and phase fluctuations of the propagating sound signals, loss of signal coherence, changes in the interference maxima and minima of the direct ground reflected waves, and multipath effects. Understanding these effects is important for a variety of military applications, such as acoustic source localization and classification, noise propagation in the atmosphere, and the development of new remote sensing techniques of the atmosphere.

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Green's Function Extraction from Atmospheric Acoustic Propagation

Aerospace & Defense Technology: October 2019

  • Magazine Article
  • 19AERP10_08
Published 2019-10-01 by SAE International in United States

Understanding what affects acoustic waves propagating in the atmosphere is important for a variety of military applications including the development of new remote sensing techniques.

Acoustic waves propagating in the atmosphere may undergo many effects including refraction by temperature and wind velocity gradients, scattering by atmospheric turbulence, absorption by the atmosphere (fluid), diffraction by terrain features, and absorption and reflection by a porous ground. As a result, there may be insonification in acoustic shadow zones, amplitude and phase fluctuations of the propagating sound signals, loss of signal coherence, changes in the interference maxima and minima of the direct ground reflected waves, and multipath effects. Understanding these effects is important for a variety of military applications, such as acoustic source localization and classification, noise propagation in the atmosphere, and the development of new remote sensing techniques of the atmosphere.

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Neural Lander Uses AI to Land Drones Smoothly

  • Magazine Article
  • TBMG-35288
Published 2019-10-01 by Tech Briefs Media Group in United States

Landing multi-rotor drones smoothly is difficult. Complex turbulence is created by the airflow from each rotor bouncing off the ground during a descent. This turbulence is not well understood nor is it easy to compensate for, particularly for autonomous drones. That is why takeoff and landing are often the two most difficult parts of a drone flight. Drones typically wobble and inch slowly toward a landing until power is finally cut and they drop the remaining distance to the ground.

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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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