Search

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Computational Mechanics / Jisuan Lixue Xuebao is the property of Chinese Journal of Computational Mechanics Editorial Office, Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To explore the fluid-structure interaction (FSI) effect on the wind-induced response of high-rise building, the CAARC (Commonwealth advisory aeronautical research council) high-rise building model was taken as the research object. An aeroelastic model was established based on the physical characteristics of the CAARC model. A new turbulence generation method discretizing and synthesizing random flow generation(DSRFG) was used to generate inlet turbulence. The one-way FSI and two-way FSI simulation technique was carried out by using the detached eddy simulation(DES) method. The results were compared with the wind tunnel test. It shows that the aeroelastic characteristics of the structure are consistent, and the DES method has strong applicability and accuracy in simulating the unsteady wind field. The one-way FSI and two-way FSI simulation results have great differences in flow field and windinduced response. In terms of flow field, the two-way FSI has a wider wake area near the structure than the one-way FSI. In addition to the drag coefficient, the response of the two-way FSI has a decreases trend when compared with that of the one-way FSI, and the along wind direction of the structure is also more susceptible to the fluid-structure coupling effect. On a low structural damping level, the aerodynamic damping caused by FSI effect has a great influence on the structural response, the FSI effect of high-rise buildings cannot be ignored. [ABSTRACT FROM AUTHOR]

Cavity in the supersonic flow has an obvious self-sustained pressure oscillation which causes a fierce aerodynamic noise. An open cavity which length-to-depth ratio is 5.88 is simulated to predict the noise under the condition of Ma=2.0. Both detached eddy simulation (DES) method and nonlinear acoustic method for solving the non-linear disturbance equations (NLDE) method are used. The results show that NLDE method performs better in predicting the sound pressure level (SPL), and the predicted results are in agreement with the experimental results while the peak values of cavity tones obtained by DES method are 5 dB lower than those obtained by NLDE method. However, the DES method is more accurate in predicting the mode frequencies. The reason for these differences is that the DES method can capture the noise source more accurately, and NLDE method can simulate the noise propagation better. The comparison on computing resource indicates the DES method needs high resolution mesh and small time step which leads to high cost of computing resources, and the NLDE method models the fine scale turbulent motions by synthetic turbulence on coarse mesh and large time step, thus reducing the need for computing resource significantly. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to provide a basis and some references for experimental study on aerodynamic noise of landing gears, a numerical simulation is carried out for a four-wheel rudimentary landing gear (RLG) model using the delayed detached eddy simulation (DDES) based on the S-A turbulent model. Slip wall boundary condition with different section areas are used to mimic wind tunnels with different sizes, and the non-wind-tunnel case is simulated with far field boundary conditions for the side walls and the floor. The blockage ratio β is varied from 0 to 8. 8%. Timeaveraged surface pressure coefficient and surface sound pressure level (SPL) are calculated from the simulated unsteady flow field. The results show that the mean surface SPL decreases with increasing β in general. There is a threshold β ranged of roughly 4% ~ 5%. The mean surface SPL varies sharply when β is within this range, and is insensitive with β when it is out of this range. The most β-sensitive part is the front wheel, while the most insensitive is the back wheel. This demonstrates a close relation between the aeroacoustic properties and mean flow properties at different blockage ratios. [ABSTRACT FROM AUTHOR]

A four-wheel rudimentary landing gear is studied numerically by unsteady RANS (URANS), detached eddy simulation (DES) and delayed detached eddy simulation (DDES) based on the Spalart-Allmaras turbulence model. The surface sound pressure level and sound pressure spectra are calculated using the obtained unsteady flow field. The 3 methods cost approximately the same time, with URANS slightly lower than the other two. DDES uses slightly less time than DES since it retains RANS mode in attached flow region. The investigation shows that URANS can give reasonable results in the attached flow region but cannot describe correctly the flow pattern in the detached flow. Both DES and DDES can describe the steady and unsteady properties in the flow around rudimentary landing gear. DDES is slightly superior over DES, and DES can also give reasonable results since the flow around the landing gear is a massive separated flow. The results prove the feasibility of DES type methods in massive separated unsteady flow field and aerodynamic noise prediction for landing gear, and can be used in the study of landing gear noise reduction. [ABSTRACT FROM AUTHOR]

Noise source of high-lift device consists mainly of slat noise and flap side noise. Development of accurate numerical methods is important to the aerodynamic design of low-noise high-lift systems. In this paper, a zonal LES/DES hybrid method is proposed and implemented. High-order finite difference method and three-point backward LU-SGS implicit time marching scheme are employed to solve the flow field of a three dimensional slatted airfoil of finite span. The hybrid method takes advantage of the capabilities of both large-eddy simulation (LES) and detached-eddy simulation with improved efficiency over direct LES method for the complete flow field. The computation efficiency is improved by the use of detached-eddy simulation in the non-core region, and it also helps to capture the details of the flowfield compared to RANS method; large-eddy simulation is implemented in the core region which contains complex flow to improve the simulation capabilities of full-scale flow. Computation results are validated comparing with that of the experiment data, and some analysis is carried out based on the pressure-observer near the slat cove. The research provides basis for further studies in the slat noise analysis and low-noise high lift optimization. [ABSTRACT FROM AUTHOR]