Numerical study of compression corner flowfield using Gao-Yong turbulence model

A numerical simulation of shock wave turbulent boundary layer interaction induced by a 24° compression corner based on Gao-Yong compressible turbulence model was presented.The convection terms and the diffusion terms were calculated using the second-order AUSM(advection upstream splitting method) scheme and the second-order central difference scheme,respectively.The Runge-Kutta time marching method was employed to solve the governing equations for steady state solutions.Significant flow separation-region which indicates highly non-isotropic turbulence structure has been found in the present work due to intensity interaction under the 24° compression corner.Comparisons between the calculated results and experimental data have been carried out,including surface pressure distribution,boundary-layer static pressure profiles and mean velocity profiles.The numerical results agree well with the experimental values,which indicate Gao-Yong compressible turbulence model is suitable for the prediction of shock wave turbulent boundary layer interaction in two-dimensional compression corner flows.

Influence of the Process of Worker on the Mechanical Properties of Carbon Fiber Reinforced Plastic Molded by Autoclave

The present study aims to investigate the difference of the operation process and the significant mechanical properties between expert workers and beginner workers clearly. The influence of the performance of the carbon fiber reinforced plastic (CFRP) molds made by subjects with difference skill level was discussed. Subjects were allowed to choose their process and molding tools. Subject A had 13 years,and subject B had 1 year of professional experience.The time spent usage of tools and process was recorded by a video camera used for analysis and comparison. Mechanical properties assessed in this study include tensile,compressive and Izod impact properties. The working time analysis shows that subject A needs short time for each process. On the other hand,subject B takes twice time to work for each process compared with subject A. From the surface and cross-section observation, it was found that the molding made by subject B had wrinkles all over and the disorderly inter-layer direction; on the contrary,the wrinkles on the molding surface of subject A are barely,and the inter-layer direction of which are more orderly. The results of tensile and Izod impact tests show that the surface winkles have little influence on the mechanical properties of the molding. According to the compression test and failure structure analysis in edge corner part,it was found that it had a great influence on the compression mechanical properties of the sample belonging to different subjects with different experience.

Bayesian parameter estimation of SST model for shock wave-boundary layer interaction flows with different strengths

The Shock Wave-Boundary Layer Interaction(SWBLI)flow generated by compression corner widely occurs in engineering.As one of the primary methods in engineering,the Reynolds Averaged Navier-Stokes(RANS)methods usually cannot correctly predict strong SWBLI flows.In addition to the defects of the eddy viscosity assumption,the uncertainty of the closure coeffi-cients in RANS models often significantly impacts the simulation results.This study performs para-metric sensitivity analysis and Bayesian calibration on the closure coefficients of the Menter k-x Shear-Stress Transport(SST)model based on the SWBLI with different strengths.Firstly,the para-metric sensitivity on prediction results is analyzed using the Sobol index.The results indicate that the Sobol indices of wall pressure and skin friction exhibited opposite fluctuation trends with the increase of SWBLI strength.Then,the Bayesian uncertainty quantification method is adopted to obtain the posterior probability distributions and Maximum A Posteriori(MAP)estimates of the closure coefficients and the posterior uncertainty of the Quantities of Interests(QoIs).The results indicate that the prediction ability for strong SWBLI of the SST model is significantly improved by using the MAP estimates,and the relative errors of QoIs are reduced dramatically.