Optimization of the aerodynamic drag reduction of a passenger hatchback car

2018 ◽  
Vol 233 (8) ◽  
pp. 2819-2836 ◽  
Author(s):  
Ziyu Guo ◽  
Yingchao Zhang ◽  
Wei Ding
Keyword(s):  
Aerodynamic Drag ◽  
Digital Simulation ◽  
Optimization Method ◽  
Computational Time ◽  
Second Phase ◽  
Grid Deformation ◽  
Design Variables ◽  
Body Design ◽  
Aerodynamic Drag Reduction ◽  
Design Style

An automatic optimization process is established employing computer-aided styling, computational fluid dynamics, grid deformation, an optimization method, and other digital simulation methods to reduce the computational time. Optimization was conducted for the aerodynamic shape of a hatchback car. Eight body design variables were selected after analysing the flow field. The first phase of body optimization was conducted for the front of the vehicle, the second phase for the rear of the vehicle, and the third phase for the global vehicle. Optimization reduced the front drag by 5.64%, then the rear drag by 7.21%, and finally the global drag by 10.34%, without changing the design style. There were interactions among those variables. The established process can be used in actual automotive styling.

Aerodynamic Automobile Shape Optimization by Incorporating Reverse Shape Design Method With CFD Analysis

2017 ◽  
Author(s):  
Kisun Song ◽  
Kyung Hak Choo ◽  
Jung-Hyun Kim ◽  
Dimitri N. Mavris
Keyword(s):  
Design Optimization ◽  
Aerodynamic Drag ◽  
Design Method ◽  
Shape Design ◽  
Cfd Analysis ◽  
Simple Arithmetic ◽  
Design Variables ◽  
3D Geometry ◽  
Geometric Entity ◽  
Aerodynamic Drag Reduction

In modern automotive industry market, there have been a lot of state-of-art methodologies to perform a conceptual design of a car; functional methods and 3D scanning technology are widely used. Naturally, the issues frequently boiled down to a trade-off decision making problem between quality and cost. Besides, to incorporate the design method with advanced optimization methodologies such as design-of-experiments (DOE), surrogate modeling, how efficiently a method can morph or recreate a vehicle’s shape is crucial. This paper accomplishes an aerodynamic design optimization of rear shape of a sedan by incorporating a reverse shape design method (RSDM) with the aforementioned methodologies based on CFD analysis for aerodynamic drag reduction. RSDM reversely recovers a 3D geometry of a car from several 2D schematics. The backbone boundary lines of 2D schematic are identified and regressed by appropriate interpolation function and a 3D shape is yielded by a series of simple arithmetic calculations without losing the detail geometric features. Besides, RSDM can parametrize every geometric entity to efficiently manipulate the shape for application to design optimization studies. As the baseline, an Audi A6 is modeled by RSDM and explored through CFD analysis for model validation. Choosing six design variables around the rear shape, 77 design points are created to build neural networks. Finally, a significant amount of CD reduction is obtained and corresponding configuration is validated via CFD.

Numerical Optimization Research on Rear Characteristic Angles Based on MIRA Model for Aerodynamic Drag Reduction

2013 ◽  
Vol 774-776 ◽  
pp. 428-432
Author(s):  
Qian Qian Du ◽  
Xing Jun Hu ◽  
Qi Fei Li ◽  
Yu Kun Liu ◽  
Bo Yang
Keyword(s):  
Inclination Angle ◽  
Numerical Optimization ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Optimization Method ◽  
Aerodynamic Design ◽  
Rear Window ◽  
Passenger Car ◽  
Two Parameters ◽  
Aerodynamic Drag Reduction

The rear characteristic angles of the passenger car in this study were defined as the inclination angle of rear window and the bottom inclination angle of aft based on the MIRA model. The numerical optimization method was used to analyze the influence of combined variation of two angles on the external flow field and the CD of the passenger car, in which we combined genetic algorithm with the CFD simulation to reduce aerodynamic drag by seeking the relatively optimal combination of two parameters above. The study reveals that when the combination of the inclination angle of rear window and bottom inclination angle of aft is 25oand 0.067o, the total pressure and streamline distribution in the flow fields of the MIRA model are improved greatly and the CD is reduced compared with the worst combination. This conclusion will have profound guiding significance in the aerodynamic design of the rear styling and shape of a car.

An Aerodynamic Optimization Procedure for the Preliminary Design of Centrifugal Compressor Stages

2008 ◽  
Author(s):  
Omar Elshamy ◽  
Nidal Ghizawi ◽  
Ce´line Yon ◽  
Simone Pazzi ◽  
Denis Guenard
Keyword(s):  
Centrifugal Compressor ◽  
Optimization Procedure ◽  
Optimization Method ◽  
Computational Time ◽  
Preliminary Design ◽  
Trial And Error ◽  
Aerodynamic Optimization ◽  
Peak Efficiency ◽  
Stage Design ◽  
Design Variables

This paper presents an automated aerodynamic optimization procedure for the preliminary design of centrifugal compressors. The proposed procedure interfaces a well-validated prediction tool with a GE in-house developed optimization code (PEZ). In GE Oil & Gas this tool is used to predict the performance of a single centrifugal compressor stage the outline of which requires more than thirty geometric parameters to be set. In the early phase of a new stage design, the designer manually varies all related parameters in the framework of a trial-and-error approach. The optimization procedure eliminates the inconvenience of a vast amount of manually launched simulations required by variations of the large number of design variables. Additionally, this procedure can perform trade-off studies and sensitivity analysis. In this case the optimization plan consists of a differential evolution (DE) genetic algorithm followed by a simplex-based optimization method (AMOEBA). The procedure was challenged with several existing designs by setting different objective/constraints combinations. The optimizer was often able to improve the predicted performance, as for an old 2D design where it was possible to increase the peak efficiency of approximately 2.6%. Also, the algorithm proved able to maximize the polytropic head (+12% with respect to baseline), while keeping unaltered both surge and choke limits. The computational time was about 40 hours per case on a Windows workstation (3.20 GHz, 3.5 GB RAM).

Reduction in the aerodynamic drag around a generic vehicle by using a non-smooth surface

2016 ◽  
Vol 231 (1) ◽  
pp. 130-144 ◽  
Author(s):  
Yiping Wang ◽  
Cheng Wu ◽  
Gangfeng Tan ◽  
Yadong Deng
Keyword(s):  
Drag Reduction ◽  
Drag Coefficient ◽  
Surrogate Model ◽  
Smooth Surface ◽  
Aerodynamic Drag ◽  
Optimal Solution ◽  
Optimization Method ◽  
Aerodynamic Optimization ◽  
Design Variables ◽  
Aerodynamic Drag Coefficient

Numerical investigations are carried out to investigate the reduction in the aerodynamic drag of a vehicle by employing a dimpled non-smooth surface. The computational scheme was validated by the experimental data reported in literature. The mechanism and the effect of the dimpled non-smooth surface on the drag reduction were revealed by analysing the flow field structure of the wake. In order to maximize the drag reduction performance of the dimpled non-smooth surface, an aerodynamic optimization method based on a Kriging surrogate model was employed to design the dimpled non-smooth surface. Four structure parameters were selected as the design variables, and a 16-level design-of-experiments method based on orthogonal arrays was used to analyse the sensitivities and the influences of the variables on the drag coefficient; a surrogate model was constructed from these. Then a multi-island genetic algorithm was employed to obtain the optimal solution for the surrogate model. Finally, the surrogate model and the simulation results showed that the optimal combination of design variables can reduce the aerodynamic drag coefficient by 5.20%.

A Study of an Active Rear Diffuser Device for Aerodynamic Drag Reduction of Automobiles

2012 ◽  
Author(s):  
Seung-On Kang ◽  
Jun-Ho Cho ◽  
Sang-Ook Jun ◽  
Hoon-Il Park ◽  
Ki-Sun Song ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Aerodynamic Drag ◽  
Aerodynamic Drag Reduction

scholarly journals Topology Optimization of Hard-Coating Thin Plate for Maximizing Modal Loss Factors

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 774
Author(s):  
Haitao Luo ◽  
Rong Chen ◽  
Siwei Guo ◽  
Jia Fu
Keyword(s):  
Topology Optimization ◽  
Objective Function ◽  
Composite Plates ◽  
Optimization Method ◽  
Hard Coating ◽  
Design Variables ◽  
Coating Composite ◽  
Damping Materials ◽  
Topology Optimization Method ◽  
Loss Factors

At present, hard coating structures are widely studied as a new passive damping method. Generally, the hard coating material is completely covered on the surface of the thin-walled structure, but the local coverage cannot only achieve better vibration reduction effect, but also save the material and processing costs. In this paper, a topology optimization method for hard coated composite plates is proposed to maximize the modal loss factors. The finite element dynamic model of hard coating composite plate is established. The topology optimization model is established with the energy ratio of hard coating layer to base layer as the objective function and the amount of damping material as the constraint condition. The sensitivity expression of the objective function to the design variables is derived, and the iteration of the design variables is realized by the Method of Moving Asymptote (MMA). Several numerical examples are provided to demonstrate that this method can obtain the optimal layout of damping materials for hard coating composite plates. The results show that the damping materials are mainly distributed in the area where the stored modal strain energy is large, which is consistent with the traditional design method. Finally, based on the numerical results, the experimental study of local hard coating composites plate is carried out. The results show that the topology optimization method can significantly reduce the frequency response amplitude while reducing the amount of damping materials, which shows the feasibility and effectiveness of the method.

Nonlinear dynamic behaviour of guy cables in turbulent winds

2001 ◽  
Vol 28 (1) ◽  
pp. 98-110 ◽  
Author(s):  
Bruce F Sparling ◽  
Alan G Davenport
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Aerodynamic Drag ◽  
Numerical Study ◽  
Horizontal Displacement ◽  
Wind Loading ◽  
Second Phase ◽  
Nonlinear Coupling ◽  
Wide Range ◽  
Cable Vibrations

Large amplitude cable vibrations are difficult to predict using linear theory due to the presence of sag in the suspended profile. A numerical study was therefore undertaken to investigate the dynamic behaviour of inclined cables excited by imposed displacements. To model the nonlinear nature of cable response, a time domain finite element approach was adopted using nonlinear catenary cable elements. Two types of horizontal displacement patterns were enforced at the upper end of the guy. In the first phase of the study, harmonic displacement histories with a wide range of forcing frequencies were considered. In the second phase, random enforced displacements were used to simulate the motion of a guyed mast in gusty winds. The influence of aerodynamic drag and damping forces was investigated by performing analyses under still air, steady wind, and turbulent wind conditions. It was found that nonlinear coupling of related harmonic response components was significant at certain critical frequencies, particular when the excitation was harmonic and acted in the plane of the guy. Positive aerodynamic damping was shown to effectively suppress resonant and nonlinear coupling response.Key words: cables, structural dynamics, wind loading, finite element method, nonlinear analysis, guyed towers.

Structural Optimization of Composite Panel with Lamination Parameters and Equivalent Stiffness Laminate Method

2014 ◽  
Vol 496-500 ◽  
pp. 429-435
Author(s):  
Xiao Ping Zhong ◽  
Peng Jin
Keyword(s):  
Genetic Algorithm ◽  
Structural Optimization ◽  
Composite Structure ◽  
Optimization Procedure ◽  
Optimization Method ◽  
Composite Panel ◽  
Analysis Tool ◽  
Equivalent Stiffness ◽  
Lamination Parameters ◽  
Design Variables

Firstly, a two-level optimization procedure for composite structure is investigated with lamination parameters as design variables and MSC.Nastran as analysis tool. The details using lamination parameters as MSC.Nastran input parameters are presented. Secondly, with a proper equivalent stiffness laminate built to substitute for the lamination parameters, a two-level optimization method based on the equivalent stiffness laminate is proposed. Compared with the lamination parameters-based method, the layer thicknesses of the equivalent stiffness laminate are adopted as continuous design variables at the first level. The corresponding lamination parameters are calculated from the optimal layer thicknesses. At the second level, genetic algorithm (GA) is applied to identify an optimal laminate configuration to target the lamination parameters obtained. The numerical example shows that the proposed method without considering constraints of lamination parameters can obtain better optimal results.

Trajectory Optimization Applied to Space Rendezvous

2013 ◽  
Vol 756-759 ◽  
pp. 3466-3470
Author(s):  
Xu Min Song ◽  
Qi Lin
Keyword(s):  
Simulated Annealing ◽  
Optimization Model ◽  
Trajectory Optimization ◽  
Optimization Problem ◽  
Optimization Method ◽  
Nonlinear Constraints ◽  
Design Variables ◽  
Adaptive Simulated Annealing ◽  
Simulation Results

The trajcetory plan problem of spece reandezvous mission was studied in this paper using nolinear optimization method. The optimization model was built based on the Hills equations. And by analysis property of the design variables, a transform was put forward , which eliminated the equation and nonlinear constraints as well as decreaseing the problem dimensions. The optimization problem was solved using Adaptive Simulated Annealing (ASA) method, and the rendezvous trajectory was designed.The method was validated by simulation results.

Topology Optimization Algorithm for Plates and Shells Subjected to Plastic Deformations

1998 ◽  
Author(s):  
Kohei Yuge ◽  
Nobuhiro Iwai ◽  
Noboru Kikuchi
Keyword(s):  
Topology Optimization ◽  
Optimization Method ◽  
Homogenization Method ◽  
Finite Deformations ◽  
Thin Shells ◽  
Plastic Deformations ◽  
Material Tensor ◽  
Design Variables ◽  
Interpolation Technique ◽  
Plates And Shells

Abstract A topology optimization method for plates and shells subjected to plastic deformations is presented. The algorithms is based on the generalized layout optimization method invented by Bendsϕe and Kikuchi (1988), where an admissible design domain is assumed to be composed of microstructures with periodic cavities. The sizes of the cavities and the rotational angles of the microstructures are design variables which are optimized so as to minimize the applied work. The macroscopic material tensor for the porous material is numerically calculated by the homogenization method for the sensitivity analysis. In this paper, the method is applied to two-dimensional elasto-plastic problems. A database of the material tensor and its interpolation technique are presented. The algorithm is expanded into thin shells subjected to finite deformations. Several numerical examples are shown to demonstrate the effectiveness of these algorithms.

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