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Viewing 1 to 30 of 1866
Technical Paper
2014-10-13
Shui-chang Liu, Zheng-qi Gu, Li-fu Li, Yong Zhang, Wan-dong ZHAO
In vehicle cooling system, the essential components—radiators often interact with each other air-side flow field thereby the thermal performance. To calculate the radiators’ performance more accurately at lower time cost against the background of today’s highly competitive marketplace, based on the CFD tools, a radiator group performance prediction method of a engineering vehicle cooling system is presented in this study. During CFD simulation, the RNG k–ε turbulence model is applied and the adopted numerical methods is SIMPLE, the first upwind discrete method is used firstly to get steady flow field and the second upwind is used to reach convergence at last. Air-side flow field simulations of the radiators unit model are carried out firstly to obtain the radiators resistance and heat transfer characteristics, during which three near-wall treatments are applied respectively, and simulations result present that flow field obtained from simulation with enhanced wall treatment has the least separated flow and backflow, also pressure drop; then, the air flow and heat transfer in the whole air channel containing the radiator group are simulated to get the inlet and outlet water temperatures of radiator group, during which radiators’ are processed as porous media with heat resource distribution near to the actual condition; at last, the water temperatures obtained from simulations are compared with the test values and the temperatures according to the enhanced wall treatment has lowest relative error 6.3%, which can meet the accuracy requirement in engineering computation, so the performance calculated method proposed in this paper is effective.
Technical Paper
2014-10-13
Yufeng Li
Swirl ratio in the cylinder of a diesel engine is an important parameter for air/fuel mixing and combustion process. Swirling flow in the cylinder is formed when the intake air flows thought a helical or tangential port and inlet valve seats and then recognized by the wall of the cylinder. The swirling angular speed generated by the intake ports can be determined on a steady flow rig. The swirl ratio at the end of intake stroke in an operating engine is then estimated by equations which have already been established by Ricardo and AVL. However, the swirl ratio estimated by these existing equations is not the real value in the cylinder of an operating engine as the equations were deducted from three basic assumptions: a) volumetric efficiency of an engine is 100%; b) the pressure drop between the intake ports is constant during the engine operation; c) no burned gas residual is trapped in the cylinder. They are not true definitely. On the other hand, an accurate swirl ratio in the cylinder is essential during the engine development.
Technical Paper
2014-10-13
Yingyi Wen, Shunichi Oshima
There is a growing need to reduce torque losses in bearings that are used in automotive power transmissions and differentials for improving fuel economy. While great reductions in rolling and sliding torque are achieved, agitation torque becomes an important factor of the total torque losses in bearings, especially under sufficient lubricating conditions. So far, efforts on reducing agitation torque were taken most by means of conventional experimental trials. To improve the efficiency of development of low-torque bearings, oil flow simulation based on CFD can be considered a good solution. Aiming for speedy, low-cost development, a calculation program for predicting the amount of agitation torque and oil distribution tendency in rolling bearings has been developed using CFD analysis. To precisely simulate the air-oil two-phase flow whirling inside bearings, the author introduced a free-surface flow model using volume of fluid (VOF) method. Generally, since rolling bearings are axially symmetric, sector models (including an integral roller/ball) of bearings in vertical posture are preferred in order to reduce calculation cost.
Technical Paper
2014-10-13
Sophie Porter, Ahmad Kamal Mat Yamin, Svetlana Aleksandrova, Stephen Benjamin, Carol A. Roberts, Jonathan Saul
Flow maldistribution across automotive exhaust catalysts significantly affects their conversion efficiency. This study investigates the application of CFD in modelling flow in a 2D rig consisting of a catalyst monolith downstream of a wide-angled planar diffuser presented with steady flow. Two distinct approaches, porous medium and individual channels, are used to model monoliths of length 27mm and 100mm. Flow predictions are compared to particle image velocimetry (PIV) measurements made in the diffuser and hot wire anemometry (HWA) data taken downstream of the monolith. Upstream of the monolith, the two CFD approaches agree well for velocity profiles across the central jet. CFD predictions diverge outside of this area, with neither one markedly closer to PIV results. Modelling the monolith as a fluid region of individual channels is shown to improve the prediction of flow maldistribution downstream of the monolith when compared to the porous medium approach. The individual channels model also predicts height and placement of secondary peaks closer to those of HWA data.
Technical Paper
2014-09-30
Peter Gullberg, Antoine Tavernier
Abstract Computational Fluid Dynamics (CFD) is today an important tool in the design process of fuel and energy efficient vehicles. Under-hood management is one of the fields where CFD has proven itself to be useful for cost-efficient development of products. Multiple Reference Frame (MRF) method is the most common used tool in the industry for modeling rotating parts. In previous papers, the modeling strategy with MRF has been documented for open fans and showed high capability to predict fan performance. One of the open points of this proposed method has been its applicability to closed fans (ring fans), as industry experience and discussions has indicated previous conclusions of open fans and MRF modeling may not apply across ranges of fan designs. This paper investigates the MRF method for a closed fan with U-shroud and analyzes several aspect of the modeling strategy. The finding of this paper is that the MRF method predicts fan performance for closed fans with equal accuracy as it does for open fans.
Technical Paper
2014-09-30
Manoj K. Sampath, Figen Lacin
Abstract The Diesel engine combustion process results in harmful exhaust emissions, mainly composed of Particulate Matter (PM), Hydro Carbon (HC), Carbon monoxide (CO) and Nitrogen Oxides (NOx). Several technologies have been developed in the past decades to control these diesel emissions. One of the promising and well matured technology of reducing NOx is to implement Selective Catalytic Reduction (SCR) using ammonia (NH3) as the reducing agent. For an effective SCR system, the aqueous urea solutions should be fully decomposed into ammonia and it should be well distributed across the SCR. In the catalyst, all the ammonia is utilized for NOx reduction process. In the design stage, it is more viable to implement Computational Fluid Dynamics (CFD) for design iterations to determine an optimized SCR system based on SCR flow distribution. And in later stage, experimental test is required to predict the after-treatment system performance based on NOx reduction. The SCR model predicts the NH3 formation from urea decomposition and it is quantified at the SCR inlet, whereas experimental data involves the NOx reduction process.
Technical Paper
2014-09-30
Meng-Huang Lu, Figen Lacin, Daniel McAninch, Frank Yang
Abstract Diesel exhaust aftertreatment solutions using injection, such as urea-based SCR and lean NOx trap systems, effectively reduce the emission NOx level in various light vehicles, commercial vehicles, and industrial applications. The performance of the injector plays an important role in successfully utilizing this type of technology, and the CFD tool provides not only a time and cost-saving, but also a reliable solution for extensively design iterations for optimizing the injector internal nozzle flow design. Inspired by this fact, a virtual test methodology on injector dosing rate utilizing CFD was proposed for the design process of injector internal nozzle flows. For a low-pressure (less than 6 bar) injector application, the characteristic Reynolds number based on the diameter and mass flow rate of the inlet, return flow outlet, and nozzle exit of the injector might range from 2000 to 20000, therefore, employing a flow-physics based viscous model for building up a virtual test methodology is critical to properly capture the fluid dynamics of injector internal nozzle flow.
Technical Paper
2014-09-30
Jeff Smith, Rick Mihelic, Brandon Gifford, Matthew Ellis
Abstract On-highway tractor-trailer vehicles operate in a complex aerodynamic environment that includes influences of surrounding vehicles. Typical aerodynamic analyses and testing of single vehicles on test track, in wind tunnel or in computational fluid dynamics (CFD) do not account for these real world effects. However, it is possible with simulation and on-road testing to evaluate these aerodynamic interactions. CFD and physical testing of multiple vehicle interactions show that traffic interactions can impact the overall drag of leading and trailing vehicles. This paper will discuss results found in evaluating the effects of separation distances on tractor-trailer aerodynamics in on-road and CFD evaluations using a time-accurate Lattice Boltzmann Method based approach and the ramifications for improving real world prediction versus controlled single vehicle testing.
Technical Paper
2014-09-30
Helena Martini, Peter Gullberg, Lennart Lofdahl
Abstract Nowadays, much focus for vehicle manufacturers is directed towards improving the energy efficiency of their products. The aerodynamic drag constitutes one major part of the total driving resistance for a vehicle travelling at higher speeds. In fact, above approximately 80km/h the aerodynamic drag is the dominating resistance acting on a truck. Hence the importance of reducing this resistance is apparent. Cooling drag is one part of the total aerodynamic drag, which arises from air flowing through the heat exchangers, and the irregular under-hood area. When using Computational Fluid Dynamics (CFD) in the development process it is of great importance to ensure that the methods used are accurately capturing the physics of the flow. This paper deals with comparative studies between CFD and wind-tunnel tests. In this paper, two comparative studies are presented. One is a comparison between cooling performance simulations and chassis dynamometer measurements; the other study is a comparison between external aerodynamics simulations and wind-tunnel measurements.
Technical Paper
2014-09-30
Shaoyun Sun, Yin-ping Chang, Xinyu Wang, Qiang Fu, Kelong Lu, Zuofeng Pan, Bo Li, Heinz Friz
Abstract A challenge for the aerodynamic optimization of trucks is the limited availability of wind tunnels for testing full scale trucks. FAW wants to introduce a development process which is mainly based on CFD simulation in combination with some limited amount of wind tunnel testing. While maturity of CFD simulation for truck aerodynamics has been demonstrated in recent years, a complete validation is still required before committing to a particular process. A 70% scale model is built for testing in the Shanghai Automotive Wind Tunnel Center (SAWTC). Drag and surface pressures are measured for providing a good basis for comparison to the simulation results. The simulations are performed for the truck in the open road driving condition as well as in an initial digital model of the aerodynamic wind tunnel of SAWTC. A full size truck is also simulated in the open road driving condition to understand the scaling effect. As a 70% scale model of a heavy truck is seen to be close to the limits of the SAWTC wind tunnel, an attempt is made to understand possible wind tunnel effects by including an approximate geometry of the wind tunnel in the simulations of the scale model.
Technical Paper
2014-09-30
Haoting Wang, Tieping Lin, Xiayi Yuan, Qi Zhang
Abstract Three dimensional, steady state computational fluid dynamics (CFD) simulations of flow around a generic pickup truck are performed to optimize the aerodynamic performance of a pickup truck model. Detailed comparison between the data of the CFD model and the experiment are made. By using deformation techniques, surrogate models and optimization methods, the drag is reduced. Four design variables are used for deformation: the cabin height, bed height, ground clearance and bed length. The optimization is single objective: minimizing the drag coefficient. A response surface model is built to reduce the sampling points for optimization, and the simulation time is reduced accordingly. Results show that the design variables are not fully independent with each other, and by proper combinations of the variable change, the drag coefficient of the pickup truck model can be reduced effectively. In this study, the drag coefficient reduced about 9.7% through optimization algorithm. The results also show that the single tailgate itself is not always profitable for drag reduction.
Technical Paper
2014-09-30
Ashok Patidar, Shivdayal Prasad, Umashanker Gupta, Mohan Subbarao
Abstract In today's competitive world, vehicle with light weighting is the most focused area. Vehicle light weighting can be done either by using light weight materials or by reducing the size of the existing components. In present paper later approach of vehicle light weighting is followed. It will help in design lay outing and reduce weight will add benefit to Fuel Efficiency (FE) too. Scope for light weighting is identified in exhaust system where muffler volume is optimized using Computational Fluid Dynamics (CFD) commercial tool FLUENT™. The back pressure, exhaust gas temperature, sound noise level & sound quality are chosen as design verification parameters. The muffler volume is reduced by 14.1%; resultant system become 14.1% compact with 2% lighter weight. Initially CFD analysis is performed on existing muffler and correlated with available test results. Accordingly parameters like pressure drop and flow induced noise are set as target values for new design. Same CFD analysis process is used to find the optimum solution among the series of options available.
Technical Paper
2014-09-30
Michael S. Barton, David Corson, John Quigley, Babak Emami, Tanuj Kush
Abstract In this work, the multi-disciplinary problem arising from fluid sloshing within a partially filled tanker truck undergoing lateral acceleration is investigated through the use of multiphysics coupling between a computational fluid dynamics (CFD) solver and a multi-body dynamics (MBD) solver. This application represents a challenging test case for simulation technology within the design of commercial vehicles and is intended to demonstrate a novel approach in the field of computer aided engineering. Computer aided engineering is playing a more predominant role in the design process for commercial and passenger vehicles. Better understanding of the real time loading and responses on a vehicle during intended or unintended use can result in improved design and reduced cost over traditional designs that relied heavily on assumed loads. Liquid sloshing within the cargo tank of a commercial tanker truck results in increased loading on the vehicle's suspension when undergoing acceleration maneuvers.
Technical Paper
2014-09-28
Bongkeun Choi
Abstract In this paper an effective technology of virtual thermal test of disc brake with several advanced analytic techniques was presented. With the virtual thermal test process, thermal performance of brake system could be easily evaluated without any possibility of great errors that used to happen in the past. In addition to the classical result of CFD, this virtual thermal test produced several valuable applications such as thermal deformation of rotor, optimization of thermal performance and estimation of braking distance.
Technical Paper
2014-09-28
Nehal Goudar, Bhavesh Jain Lalwani
Abstract The detail design and development of a high drag force aerodynamics package for a high speed motorcycle is described. Numerical methods are first used to develop drag plate profiles which conform to packaging restrictions while still generating high drag forces. CFD simulation is carried on the drag plate in isolation to optimize and to validate the theoretical findings.
Technical Paper
2014-09-28
David B. Antanaitis, Heewook Lee
Abstract An area of brake system design that has remained continually resistant to objective, computer model based predictive design and has instead continued to rely on empirical methods and prior history, is that of sizing the brake pads to insure satisfactory service life of the friction material. Despite advances in CAE tools and methods, the ever-intensifying pressures of shortened vehicle development cycles, and the loss of prototype vehicle properties, there is still considerable effort devoted to vehicle-level testing on public roads using “customer-based” driving cycles to validate brake pad service life. Furthermore, there does not appear to be a firm, objective means of designing the required pad volume into the calipers early on - there is still much reliance on prior experience. This paper builds upon previous work by GM [1], where short duration, objective vehicle and dyno tests were combined with a computer model to allow for accurate pad service life prediction without vehicle tests, and expands it into a methodology combining CAE (CFD), computer modeling, objective friction material characterization data, to enable confident sizing of the brake pads very early in the vehicle development process.
Technical Paper
2014-09-28
Juan Carlos Martinez Laurent, Adrian Jordan, Francisco Canales
Abstract The brake system and components are essential active safety systems for users of motor vehicles, one common NVH phenomenon known as Brake Disc Thermal Coning creates a perception of poor braking system performance. Although Brake Disc Thermal Coning does not deteriorate the braking distance or the vehicle performance, is a concern for the customer who identifies any undesired vibration as a potential performance loss resulting in complaints and warranty claims. In order to increase the quality, and reliability of the products, Automotive OEMs have created processes and tests, today incorporating the ones based in computational solutions, to identify, prevent and correct potential issues before its present in the final product. As computer technologies like Computer Aided Design (CAD), Computer Aided Engineering (CAE) and Computer Aided Manufacturing (CAM) have become more robust, and PC power clusters have increased the complexity of the problems resolution and decreasing the solver processing time, OEMs are moving forward from the road, to the lab and today to CAE.
Technical Paper
2014-05-10
Robert E Smith, Edward Lumsdaine
Since transient vehicle HVAC computational fluids (CFD) simulations take too long to solve in a production environment, the goal of this project is to automatically create a lumped-parameter flow network from a steady-state CFD that solves nearly instantaneously. The data mining algorithm k-means is implemented to automatically discover flow features and form the network (a reduced order model). The lumped-parameter network is implemented in the commercial thermal solver MuSES to then run as a fully transient simulation. Using this network a “localized heat transfer coefficient” is shown to be an improvement over existing techniques. Also, it was found that the use of the clustering created a new flow visualization technique. Finally, fixing clusters near equipment newly demonstrates a capability to track localized temperatures near specific objects (such as equipment in vehicles).
Technical Paper
2014-04-01
Yinhong Liu, Dazhong Lao, Yixiong Liu, Ce Yang, Mingxu Qi
Abstract Variable nozzle turbine (VNT) adjusts the openings of its nozzles to insure the required flow at throat area, which broadens the operating range of the turbine, and improves the matching relationship between the turbocharger and the engine. But the changes of nozzle openings have significant influence on the flow field structure of downstream radial turbine. To evaluate this effect, the leakage flow through nozzle clearance in various nozzle openings were simulated by unsteady computational fluid dynamic (CFD). Meanwhile, the interaction between nozzle clearance leakage flow and nozzle wake were investigated to reveal its effects on aerodynamic losses and forced responses for downstream rotor. The results showed that the changes of nozzle openings not only affect the interaction between nozzle leakage flows and wake significantly, but also affect aerodynamic performance of the rotor and the blade forced response. With the decreases of nozzle openings, the nozzle leakage flow increases and the interaction between nozzle leakage flow and wake enhances.
Technical Paper
2014-04-01
Daiki Saegusa, Shinji Kawai
Abstract An analytic technology able to rapidly and accurately predict oil flows and churning torque in a transmission has been developed. The new method uses the finite difference method for analysis; with regard to wall boundaries it reproduces the shapes of physical objects by imparting boundary information to cells. This has made it a simple matter to treat the rotation and meshing of the gears, which form oil flows, and has also reduced the calculation cost. Tests of single-phase and multi-phase flows and churning torque were conducted in order to verify the accuracy of the new method. Calculation results for the flow velocity fields produced by rotating bodies, the trajectory of oil, and the behavior of the surface of the fluid displayed a good correlation with test results. Considering air entrainment in the oil, the ability of the method to reproduce these phenomena at high speeds of rotation was also increased. The method also displayed good reproduction of changes in churning torque produced by differences in the speed of rotation of the gears.
Technical Paper
2014-04-01
Daniela Siano, Luigi Teodosio, Vincenzo De Bellis, Fabio Bozza
Abstract The present paper reports 1D and 3D CFD analyses of the air-filter box of a turbocharged VVA engine, aiming to predict and improve the gas-dynamic noise emissions through a partial re-design of the device. First of all, the gas-dynamic noise at the intake mouth is measured during a dedicated experimental campaign. The developed 1D and 3D models are then validated at full load operation, based on experimental data. In particular, 1D model provides a preliminary evaluation of the radiated noise and simultaneously gives reliable boundary conditions for the unsteady 3D CFD simulations. The latter indeed allow to better take into account the geometrical details of the air-filter and guarantee a more accurate gas-dynamic noise prediction. 3D CFD analyses put in evidence that sound emission mainly occur within a frequency range of 350 to 450 Hz. Starting from the above result, the original air-box design is modified through the installation of a single Helmholtz resonator, taking into account layout constraints and the influence on engine performance, as well.
Technical Paper
2014-04-01
Emma Frosina, Adolfo Senatore, Dario Buono, Micaela Olivetti
Abstract In recent years, in order to optimize performance and exhaust emissions of internal combustion engines, the design of auxiliary systems assumed a particular importance especially due to the need to obtain higher efficiency and reduce power losses required by these components. In this sense, looking at the lubrication circuit, it appears important to use solutions that allow to optimize the fluid dynamics of both the ducts and the pump. In this paper a tridimensional CFD analysis of a lubrication circuit oil pump of a modern high-performance engine will be shown. In this particular application there is a variable displacement pump used to optimize the operative conditions of the lubricant circuit in all engine running conditions. This variable displacement pump changes the positions of the ring as a function of the boundary conditions. The model was build up with PumpLinx®, a commercial CFD 3D code developed by Simerics Inc.®, taking into account all the thermo-fluid dynamic conditions with particular attention to the cavitation phenomena.
Technical Paper
2014-04-01
Xiao Hu, Scott Stanton
Abstract Due to growing interest in hybrid and electric vehicles, li-ion battery modeling is receiving a lot of attention from designers and researchers. This paper presents a complete model for a li-ion battery pack. It starts from the Newman electrochemistry model to create the battery performance curves. Such information is then used for cell level battery equivalent circuit model (ECM) parameter identification. 28 cell ECMs are connected to create the module ECM. Four module ECMs are connected through a busbar model to create the pack ECM. The busbar model is a reduced order model (ROM) extracted from electromagnetic finite element analysis (FEA) results, taking into account the parasitic effects. Battery thermal performance is simulated first by computational fluid dynamics (CFD). Then, a thermal linear and time-invariant (LTI) ROM is created out of CFD solution. The thermal LTI ROM is then two-way coupled with the battery pack ECM to form a complete battery pack model. Thanks to the ROM technology, such a battery pack model can finish a complete charge discharge cycle within seconds of simulation time.
Technical Paper
2014-04-01
Teresa Donateo, Antonio Paolo Carlucci, Luciano Strafella, Domenico Laforgia
Abstract An analytical methodology to efficiently evaluate design alternatives in the conversion of a Common Rail Diesel engine to either CNG dedicated or dual fuel engine has been presented in a previous investigation. The simulation of the dual fuel combustion was performed with a modified version of the KIVA3V code including a modified version of the Shell model and a modified Characteristic Time Combustion model. In the present investigation, this methodology has been validated at two levels. The capability of the simulation code in predicting the emissions trends when changing pilot specification, like injected amount, injection pressure and start of injection, and engine configuration parameters, like compression ratio and axial position of the diesel injector has been verified. The second validation was related to the capability of the proposed computer-aided procedure in finding optimal solutions in a reduced computational time. Therefore, a multi-objective genetic algorithm was run for 100 generations with a population of 50 individuals including the same geometric and control variables taken into account in the first validation.
Technical Paper
2014-04-01
Donghoon Kim, Kihyun Kim
Abstract Researches about gasoline direct injection compression ignition engine (GDCI), a compression Ignition (CI) engine fueled with gasoline instead of diesel, are getting great attention for operation of the CI engine under higher load conditions with low smoke and nitrogen oxides (NOx) emission due to high volatility and low auto-ignitability of gasoline. In this engine, it is very important to investigate gasoline spray characteristics inside the cylinder compared to diesel. Recently, many researchers are using computational fluid dynamics (CFD) as a useful tool to investigate the spray characteristics of these two fuels inside the internal combustion engines. To simulate gasoline and diesel sprays inside the cylinder, higher volatility of gasoline than those of diesel should be considered properly. Of many spray sub-models, evaporation model is more important model to simulate liquid-vapor phase change in evaporating condition and the accuracy of calculated liquid length is decided by this model.
Technical Paper
2014-04-01
Kamalesh Bhambare, Junya Fukuyama, Jaehoon Han, Kosuke Masuzawa, Akihiro Iwanaga, Steven Patterson
Abstract The climate inside a vehicle cabin is affected by the performance of the vehicle HVAC system, the thermal characteristics of the vehicle structure and the components, as well as the external environmental conditions. Due to the complex interactions among these various factors, the flow field and the temperature distribution can be very complicated. The need for a fully three-dimensional transient analysis is increasing in order to provide sufficiently detailed information that can be used to improve the vehicle design. In this study, a numerical simulation methodology to predict the local climate conditions in a passenger vehicle cabin is presented. The convective heat transfer from both the exterior and the interior of the cabin were calculated by three dimensional CFD simulations using a Lattice-Boltzmann method based flow solver. The conduction and the radiation effects including the solar loading were solved using a finite-difference based radiation-conduction thermal solver.
Technical Paper
2014-04-01
Sandip Pawar, Upender Rao Gade, Atish Dixit, Suresh Babu Tadigadapa, Sambhaji Jaybhay
Abstract The objective of the work presented in this paper is to provide an overall CFD evaluation and optimization study of cabin climate control of air-conditioned (AC) city buses. Providing passengers with a comfortable experience is one of the focal point of any bus manufacturer. However, detailed evaluation through testing alone is difficult and not possible during vehicle development. With increasing travel needs and continuous focus on improving passenger experience, CFD supplemented by testing plays an important role in assessing the cabin comfort. The focus of the study is to evaluate the effect of size, shape and number of free-flow and overhead vents on flow distribution inside the cabin. Numerical simulations were carried out using a commercially available CFD code, Fluent®. Realizable k - ε RANS turbulence model was used to model turbulence. Airflow results from numerical simulation were compared with the testing results to evaluate the reliability. Qualitative parameters such as mean Age of Air (AOA), Broadband Noise model, and Human Thermal Comfort Module (PMV/PPD) were used to gain deeper insight into the problem.
Technical Paper
2014-04-01
Yingchao Zhang, Wei Ding, Yu Zhang
Abstract Automobile industry is facing the great challenge of energy conservation and emission reduction. It's necessary to do some researches on some surface components of a car body to find out which of them may affect aerodynamic drag remarkably. This will help an aerodynamic engineer modify an initial car model more clearly. We also hope to reduce the cost during the process, including time and resources. In this paper, with the purpose of developing an aerodynamic shape optimization process and realizing its automation, a MIRA reference car model was studied and three commercial softwares were integrated-Altair HyperStudy, HyperMesh and CD-adapco STAR-CCM+. The optimization strategy in this paper was: firstly, a DOE (design of experiment) matrix, which contained four design factors and thirty levels was created. The baseline model was morphed according to the DOE matrix. Then the morphed model's aerodynamic drag coefficient (Cd) and lift coefficient (Cl) were calculated via CFD software.
Technical Paper
2014-04-01
Mark E. Gleason, Todd Lounsberry, Khaled Sbeih, Sreekanth Surapaneni
Abstract Recently, the Two-Measurement correction method that yields a wake distortion adjustment for open jet wind tunnels has shown promise of being able to adjust for many of the effects of non-ideal static pressure gradients on bluff automotive bodies. Utilization of this adjustment has shown that a consistent drag results when the vehicle is subjected to the various gradients generated in open jet wind tunnels. What has been lacking is whether this consistent result is independent of the other tunnel interference effects. The studies presented here are intended to fill that gap and add more realistic model and wind tunnel conditions to the evaluations of the performance of the two-measurement technique. The subject CFD studies are designed to greatly reduce all wind tunnel interference effects except for the variation of the non-linear static pressure gradients. A zero gradient condition is generated by simulating a solid wall test section with a blockage ratio of 0.1%. The non-linear gradients are simulated using a semi-open jet test section with a very large 40 square meter nozzle exit and a variable length test section.
Technical Paper
2014-04-01
Andreas Kremheller
Abstract This paper aims to provide a brief description on the aerodynamics development process of the new Nissan Qashqai using full-scale wind tunnel testing and Computational Fluid Dynamics simulations (CFD). Aerodynamic drag reduction ideas were developed by means of numerical simulations with confirmation of the aerodynamics properties full-scale clay models were tested in the wind tunnel. Key aerodynamic features were developed including the optimization of hood and windscreen angle, roof camber, plan view corner radius, rear combination lamp with boundary layer trip edge and a large rear spoiler with incorporated winglet. The drag contribution of the under body was reduced by optimizing deflectors and panels. The A-pillar and door mirrors were designed to reduce drag and wind noise. Furthermore, the bumper opening area was optimized to balance the airflow for engine cooling and a low cooling drag contribution. In addition, an active grille shutter was developed to limit the amount of cooling airflow into the lower bumper opening to a minimum.
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