DSMC Simulation and Experimental Validation of Shock Interaction in Hypersonic Low Density Flow

Hong Xiao,Di Wu,Yuhe Shang

doi:10.1155/2014/732765

Hong Xiao, Di Wu + Show 1 more

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https://doi.org/10.1155/2014/732765

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Abstract

Direct simulation Monte Carlo (DSMC) of shock interaction in hypersonic low density flow is developed. Three collision molecular models, including hard sphere (HS), variable hard sphere (VHS), and variable soft sphere (VSS), are employed in the DSMC study. The simulations of double-cone and Edney's type IV hypersonic shock interactions in low density flow are performed. Comparisons between DSMC and experimental data are conducted. Investigation of the double-cone hypersonic flow shows that three collision molecular models can predict the trend of pressure coefficient and the Stanton number. HS model shows the best agreement between DSMC simulation and experiment among three collision molecular models. Also, it shows that the agreement between DSMC and experiment is generally good for HS and VHS models in Edney's type IV shock interaction. However, it fails in the VSS model. Both double-cone and Edney's type IV shock interaction simulations show that the DSMC errors depend on the Knudsen number and the models employed for intermolecular interaction. With the increase in the Knudsen number, the DSMC error is decreased. The error is the smallest in HS compared with those in the VHS and VSS models. When the Knudsen number is in the level of 10−4, the DSMC errors, for pressure coefficient, the Stanton number, and the scale of interaction region, are controlled within 10%.

Highlights

Shock interactions play an important role in hypersonic flows
When the Kn number is in the level of 10−4, the Direct simulation Monte Carlo (DSMC) error for pressure coefficient and Stanton number is controlled within 10%
Molecular models were employed with DSMC including the hard sphere (HS), variable hard sphere (VHS), and variable soft sphere (VSS) models

Summary

Introduction

Shock interactions play an important role in hypersonic flows. In the past decade, significant efforts in computational fluid dynamics (CFD) have been exerted to develop prediction techniques for simulating these complex flow structures [1,2,3]. The gradient of flow property ∂φ/∂x is large, because characteristic dimension L is small It causes the Knudsen number becomes big in the inner of shock. Some double-cone flow simulation studies, including Candler’s ect CFD [7] and Moss DSMC simulation [8], have been conducted In these studies, comparisons between simulation and experiment reveal significant numerical problems that can be encountered when predicting strong gradients. HS and VSS models were not included in Moss’s DSMC simulation Edney’s type IV shock interaction is studied

DSMC Model

Hypersonic Double-Cone Flow Simulation

Type IV Shock Interaction Simulation

Findings

Conclusion