Instability of a shear layer between multicomponent fluids at supercritical pressure

Qing-Fei Fu,Li-Jun Yang,Yun-Xiao Zhang,Chao-Jie Mo

doi:10.1063/1.5021835

Abstract

The temporal instability of a thin shear layer lying between streams of two components of fluids has been studied. The effects of density profile of the layer on the instability behavior were mainly considered. The detailed density profile was obtained through Linear Gradient Theory. The eigenvalue problem was calculated, and the temporal instability curves were obtained for the thermodynamic parameters, e.g. pressure and temperature. The results show that, increase of pressure leads to the increase of the maximum growth rate. However, increasing pressure has opposite effects on the disturbances with small and large wave length. The increase of temperature causes the decrease of disturbance growth rate. The instability behavior of the shear layers was determined mainly by the interval between the inflections of the velocity and density profiles, and the maximum density gradient. The total effects, determined by coupling density stratification, and interval between the inflections of the velocity and density profiles, were quite distinct for different ranges of temperature and pressure.

Highlights

In recent years, the liquid rocket engines have developed rapidly, providing much greater thrust than before
In previous study on stability of one-component fluid shear layer,[20] the density profile was obtained using the equation of state and the temperature profile given in the form of a hyperbolic tangent function
We will focus on the stability characteristics of the shear layer when its thermodynamic parameters pass through the critical condition

Summary

INTRODUCTION

The liquid rocket engines have developed rapidly, providing much greater thrust than before. Dahms and Oefelein[6] derived a model based on a modified 32-term Benedict-Webb-Rubin equation of state that accounts for the relevant real-fluid thermodynamic, and Linear Gradient Theory that describes the detailed molecular structure of the vapor-liquid interface region. Okong’O and Bellan[15] performed a temporal instability analysis of supercritical binary-species mixing layers They discussed the effects of mean flow profiles (e.g. similarity solutions and error-function profiles) on the stability of supercritical heptane/nitrogen and oxygen/hydrogen mixtures. Zong et al.[16] considered the real gas effects, and predicted the frequency of disturbance waves with the largest spatial growth rate, using a linear stability model In their works, the mean density profiles were given with a hyperbolic tangent function. A temporal stability analysis of a shear layer formed by the injection of N-dodecane jet into supercritical nitrogen environment was performed. The influence of some thermodynamic parameters on the temporal instability of the transcritical two-component shear layer was investigated in detail

THEORETICAL FRAMEWORK

RESULTS AND DISCUSSION

Effects of pressure

CONCLUSIONS