CFD Simulation of a Simplified Automotive Model for Various Rear Slant Angle

2014 ◽  
Vol 660 ◽  
pp. 724-729
Author(s):  
S. Mansor ◽  
N.A.R. Nik Mohd ◽  
C.W. Chung
Keyword(s):  
Constant Velocity ◽  
Cfd Simulation ◽  
Pressure Coefficient ◽  
Wind Tunnel Test ◽  
Slant Angle ◽  
Testing Method ◽  
Design Changes ◽  
Yaw Angle ◽  
Height Model ◽  
Early Design Phase

In the early design phase of automotive sector, the flow field around the vehicle is important in decision making on design changes. It would consume a lot of money and time for multiple prototypes development if adopt traditional testing method which is wind tunnel test. Thus, CFD Simulation plays an important role here. In this paper, a CFD simulation study was conducted on a simplified automotive model called Davis model with constant velocity of 40 m/s. Modification of rear slant angle bring significant effects on the wakes produced which also affect the drag performance. Many configurations of body designs can be produced by a single rear slant angle. So that, fixed rear slope and fixed rear height configuration have been chosen for investigations for various rear slant angles. In this paper, the flow of Davis model especially on the rear slanted surface is discussed. Pressure coefficient contour, pressure coefficient plot and vorticity structures are presented. This work shows that the drag coefficient value vary between fixed rear slope model and fixed rear height model even for the same rear slant angle under a range of yaw angle.

Validation of CFD Modeling and Simulation of a Simplified Automotive Model

2015 ◽  
Vol 735 ◽  
pp. 319-325
Author(s):  
S. Mansor ◽  
N.A.R. Nik Mohd ◽  
C.W. Chung
Keyword(s):  
Wind Tunnel ◽  
Modeling And Simulation ◽  
Best Practice ◽  
Cfd Simulation ◽  
Wind Tunnel Test ◽  
Turnaround Time ◽  
Cfd Modeling ◽  
Design Changes ◽  
Wind Tunnel Data ◽  
Simulation Results

In the early design phase of automotive sector, the flow field around the vehicle is important in decision making on design changes. It would consume a lot of money and time for multiple prototypes development if adopt traditional testing method which is wind tunnel test. Thus, numerical method such as Computational Fluid Dynamics (CFD) simulation plays an important role here. It is very often simulation results been compared with wind tunnel data. However, with various mesh types, meshing methodology, discretization methods and different solver control options in CFD simulation, users may feel low confidence level with the generated simulation results. Thus, a robust modeling and simulation guideline which would help in accurate prediction should be developed due to the industry’s demand for accuracy when comparing CFD to wind tunnel results within short turnaround time. In this paper, a CFD modeling and simulation study was conducted on a simplified automotive model to validate with wind tunnel test results. The wind tunnel environment was reproduced in the simulation setup to include same boundary conditions. Meshing guidelines, turbulence model comparisons and also the best practice for solver setup with respect to accuracy will be presented. Overall, CFD modeling and simulation methods applied in this paper are able to validate the results from experiment accurately within small yaw ranges.

Wind Tunnel Test and the Analysis of Buffeting Performance of Free-Standing Tower of Cable-Stayed Bridge under Yaw Wind

2012 ◽  
Vol 532-533 ◽  
pp. 215-219
Author(s):  
Guo Hui Zhao ◽  
Yu Li ◽  
Hua Bai
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Free Standing ◽  
Buffeting Response ◽  
Cable Stayed Bridge ◽  
Aeroelastic Model ◽  
Navigation Channel ◽  
Yaw Angle

The buffeting performance of free-standing tower of JiangHai Navigation Channel Bridge, a cable-stayed bridge, under yaw wind is investigated by means of wind tunnel test of aeroelastic model. It is found that the variation of buffeting response of free-standing tower with wind yaw angle is not monotonous. The lateral buffeting response on the top of the free-standing tower reach their minimal values and maximal values at around 150°and 180°of wind yaw angle respectively and the longitudinal buffeting response attain their maximal values at around 90°of wind yaw angle. Also, at the 2/3 height of the tower the lateral buffeting response and torsional buffeting response get their minimal values at around 150°of wind yaw angle, and at around 180°achieve the maximal values. It is also seen that, the buffeting response changes with the wind speed at a conic curve approximately.

scholarly journals Normal forces exerted upon a long cylinder oscillating in an axial flow

2014 ◽  
Vol 752 ◽  
pp. 649-669 ◽  
Author(s):  
L. Divaret ◽  
O. Cadot ◽  
P. Moussou ◽  
O. Doaré
Keyword(s):  
Flow Velocity ◽  
Normal Force ◽  
Pressure Coefficient ◽  
Axial Flow ◽  
Fluid Forces ◽  
Normal Forces ◽  
Pressure Distributions ◽  
Damping Rate ◽  
Static Approach ◽  
Yaw Angle

AbstractThis work aims to improve understanding of the damping induced by an axial flow on a rigid cylinder undergoing small lateral oscillations within the framework of the quasistatic assumption. The study focuses on the normal force exerted on the cylinder for a Reynolds number of $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\mathit{Re}=24\, 000$ (based on the cylinder diameter and axial flow velocity). Both dynamic and static approaches are investigated. With the static approach, fluid forces, pressure distributions and velocity fields are measured for different yaw angles and cylinder lengths in a wind tunnel. It is found that for yaw angles smaller than $5{^\circ }$, the normal force varies linearly with the angle and is fully dominated by its lift component. The lift originates from the high pressure coefficient at the front of the cylinder, which is found to depend linearly on the angle, and from a base pressure coefficient that remains close to zero independent of the yaw angle. At the base, a flow deficit and two counter-rotating vortices are observed. A numerical simulation using a $k\mbox{--}\omega $ shear stress transport turbulence model confirms the static experimental results. A dynamic experiment conducted in a water tunnel brings out damping-rate values during free oscillations of the cylinder. As expected from the linear dependence of the normal force on the yaw angle observed with the static approach, the damping rate increases linearly with the axial flow velocity. Satisfactory agreement is found between the two approaches.

scholarly journals Optimization for Cavitation Inception Performance of Pump-Turbine in Pump Mode Based on Genetic Algorithm

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Ran Tao ◽  
Ruofu Xiao ◽  
Wei Yang ◽  
Fujun Wang ◽  
Weichao Liu
Keyword(s):  
Genetic Algorithm ◽  
Pressure Drop ◽  
Cfd Simulation ◽  
Pressure Coefficient ◽  
Leading Edge ◽  
Algorithm Optimization ◽  
Pump Mode ◽  
Local Flow ◽  
Cavitation Inception ◽  
Blade Thickness

Cavitation is a negative factor of hydraulic machinery because of its undesirable effects on the operation stability and safety. For reversible pump-turbines, the improvement of cavitation inception performance in pump mode is very important due to the strict requirements. The geometry of blade leading edge is crucial for the local flow separation which affects the scale and position of pressure drop. Hence, the optimization of leading edge shape is helpful for the improvement of cavitation inception performance. Based on the genetic algorithm, optimization under multiple flow rate conditions was conducted by modifying the leading edge ellipse ratio and blade thickness on the front 20% meanline. By using CFD simulation, optimization was completed with obvious improvements on the cavitation inception performance. CFD results show that the pressure drop location had moved downstream with the increasement of the minimum pressure coefficient. Experimental verifications also got an obvious enhancement of cavitation inception performance. The stability and safety was improved by moving the cavitation inception curve out of the operating range. This optimization is proved applicable and effective for the engineering applications of reversible pump-turbines.

Current Drag From Tow and Wind Tunnel Tests of a FLNG Hull

2016 ◽  
Author(s):  
Zhenjia (Jerry) Huang ◽  
Jang Kim ◽  
Hyunchul Jang ◽  
Scott T. Slocum
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Model Test ◽  
Cfd Simulation ◽  
Wind Tunnel Test ◽  
Model Tests ◽  
Additional Contribution ◽  
Wind Tunnel Model ◽  
Tunnel Model ◽  
Current Drag

In this paper, the current drag of a barge-shaped floating liquefied natural gas (FLNG) vessel was studied. Three model tests were performed — a wind tunnel model test, a submerged double-body tow test and a surface tow test. Computational fluid dynamics (CFD) simulations were carried out to gain further insights into the test results. During testing, the tow speed was kept low to avoid surface waves. When the current heading was around the beam current direction, the transverse drag coefficient measured from the wind tunnel test was significantly lower than those of the submerged tow and surface tow tests. The submerged tow and the surface tow provided similar drag coefficients. Results presented in this paper indicated that the difference between the wind tunnel test and the tow tests was caused by the wind tunnel boundary layer effect on the incoming wind profile and formation of a recirculation zone on the upstream side of the model, with a possible additional contribution from the wind tunnel floor constraint on the flow in the wake. Such effects are not accounted for with the simple corrections based on flow velocity reduction in the wind tunnel boundary layer. When conducting future wind tunnel model tests for barge-shaped FLNG hulls, one should consider the potential under-measurement of the transverse drag. In this paper, details of the FLNG model, test setup, test quality assurance (QA), measurement and CFD simulation results are presented, as well as discussions and recommendations for model testing.

scholarly journals A Parametric Design Method for Hybrid Airfoils for Icing Wind Tunnel Test

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Zhao Li ◽  
Guang-jun Yang ◽  
Xiao-yan Tong ◽  
Feng Jiang
Keyword(s):  
Flow Field ◽  
Parametric Design ◽  
Design Method ◽  
Pressure Coefficient ◽  
Wind Tunnel Test ◽  
Leading Edge ◽  
Full Scale ◽  
Navier Stokes ◽  
Ice Accretion ◽  
Multiple Control

The size of aircraft models that can be tested in icing wind tunnels is limited by the dimensions of the facilities in present; it is an effective method to replace the large model with a hybrid airfoil to carry out the experiment. A design method of multiple control points for hybrid airfoil based on the similarity of flow field in the leading edge of airfoil is proposed. Aiming at generating the full-scale flow field and ice accretion on the leading edge, multiobjective genetic optimization algorithm is used to design the hybrid airfoil under different conditions by combining the airfoil parameterization and solution of spatial constraint. Pressure tests of hybrid airfoils are carried out and compared with the leading edge pressure of the corresponding full-scale airfoils. The design and experimental results show that the pressure coefficient deviation between the hybrid airfoils designed and the corresponding full-scale airfoil in the 15% chord length range of the leading edge is within 4%. Finally, the vortex distribution and ice accretion process of the two airfoils were simulated by the unsteady Reynolds-averaged-Navier–Stokes (URANS) equations and multistep ice numerical method; it is shown that the hybrid airfoil can provide the same vortex distribution and ice accretion with the full-scale airfoil.

How Uncertain Is Too Uncertain? Validity Tests for Early Resilient and Risk-Based Design Processes

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Daniel Hulse ◽  
Christopher Hoyle ◽  
Irem Y. Tumer ◽  
Kai Goebel
Keyword(s):  
Design Process ◽  
Epistemic Uncertainty ◽  
Expected Value ◽  
Design Phase ◽  
Design Processes ◽  
Early Design ◽  
Design Changes ◽  
High Level ◽  
The Cost ◽  
Early Design Phase

Abstract A number of risk and resilience-based design methods have been put forward over the years that seek to provide designers the tools to reduce the effects of potential hazards in the early design phase. However, because of the associated high level of uncertainty and low-fidelity design representations, one might justifiably wonder if using a resilient design process in the early design phase will reliably produce useful results that would improve the realized design. This paper provides a testing framework for design processes that determines the validity of the process by quantifying the epistemic uncertainty in the assumptions used to make decisions. This framework uses this quantified uncertainty to test whether three metrics are within desirable bounds: the change in the design when uncertainty is considered, the increase in the expected value of the design, and the cost of choice-related uncertainty. This approach is illustrated using two examples to demonstrate how both discrete and continuous parametric uncertainty can be considered in the testing procedure. These examples show that early design process validity is sensitive to the level of uncertainty and magnitude of design changes, suggesting that while there is a justifiable decision-theoretic case to consider high-level, high-impact design changes during the early design phase, there is less of a case to choose between relatively similar design options because the cost of making the choice under high uncertainty is greater than the expected value improvement from choosing the better design.

scholarly journals Forecasting of Wind Induced Pressure on Setback Building Using Artificial Neural Network

2020 ◽  
Author(s):  
Amlan Kumar Bairagi ◽  
Sujit Kumar Dalui
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Cfd Simulation ◽  
Incidence Angle ◽  
Pressure Coefficient ◽  
Tall Building ◽  
The Face ◽  
Artificial Neural ◽  
Artificial Neural Network Ann ◽  
Target Data

The wind load on an irregular plan shape tall building is quite different compared to a conventional plan shape tall building. Especially the aerodynamic parameters have extreme change due to the variety of setbacks at one or more the disparity of level. This paper highlights the prediction of pressure coefficient on square, single (20 %) setback and double (10 %) setback buildings for any wind incidence angle by CFD simulation and validated with Artificial Neural Network (ANN) and fast Fourier transform. The ANN is a widely used and efficient tool for different types of analyses. The 0° to 180° wind incidence angles (WIAs) considered as input data and respective face wise pressure coefficient (Cp) used as target data. The Levenberg-Marquardt training function and Mean Square Error (MSE) performance function used to train the target data. The face wise graphs of CFD, ANN and FFT are plotted in a single graph and the Cp of the surface checked by any random WIAs. Amazingly, the Cp of random WIA by ANN is almost similar to CFD. Furthermore, the error of ANN is 0.6 % to 2.5 %, which is negligible. According to this predicted graph, the design Cp of any WIA can be easily calculated and implement directly in the design.

scholarly journals Numerical CFD Simulation and Test Correlation in a Flight Project Environment

2015 ◽  
Author(s):  
K. K. Gupta ◽  
S. F. Lung ◽  
A. H. Ibrahim
Keyword(s):  
Wind Tunnel ◽  
Test Data ◽  
Cfd Simulation ◽  
Wind Tunnel Test ◽  
Flight Testing ◽  
Project Environment ◽  
Test Correlation

This paper presents detailed description of a novel CFD procedure and comparison of its solution results to that obtained by other available CFD codes as well as actual flight and wind tunnel test data pertaining to the GIII aircraft, currently undergoing flight testing at AFRC.

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