Two-dimensional quantitative visualization of isolator shock trains by rainbow schlieren deflectometry

Masashi Kashitani,Atsushi Matsuyama,Shinichiro Nakao,Daisuke Ono,P. Dančová,Yoshiaki Miyazato

doi:10.1051/epjconf/201818002063

Masashi Kashitani, Atsushi Matsuyama

Open Access

https://doi.org/10.1051/epjconf/201818002063

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Abstract

The rainbow schlieren deflectometry is effective in studying quantitatively the density fields in shock-containing free jets at high precision and high spatial resolution. However, there has been no practical application of rainbow schlieren deflectometry for shock trains in a confined duct. Therefore, in the present study, the rainbow schlieren deflectometry is applied to the flow field including a shock train in a constant-area duct where just upstream of the shock train the freestream Mach number is 1.34, the unit Reynolds number is 5.39 × 107 m-1, and the boundary layer displacement thickness is 0.149 mm. As a result, a two- dimensional density field of the shock train is for the first time quantitatively displayed and the fine structure of the shock train is illustrated as a color gradation representation.

Highlights

Over the past few decades, the development of dualmode scramjet engines for realizing next-generation propulsion systems has been aggressively conducted
Being able to predict the length of a precombustion shock structure is the key component of isolator design for dual-mode scramjet engines
A typical rainbow schlieren picture of a shock train is presented in Fig. 6 with the flow from left to right

Summary

Introduction

Over the past few decades, the development of dualmode scramjet engines for realizing next-generation propulsion systems has been aggressively conducted. Being able to predict the length of a precombustion shock structure is the key component of isolator design for dual-mode scramjet engines. Such a repeated shock structure appears in a variety of flow-devices including supersonic wind tunnels, supersonic ejectors, supersonic inlets of aircraft engines, etc and has been called in many ways by many researches, multiple shocks, shock system, for example. We refer to such a series of shocks as a "shock train". A review of the past experimental, theoretical, and numerical investigations on the subject of shock train and pseudoshock phenomena in internal gas flows is given by Matsuo et al [1]

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