Experimental investigation of interactions between turbulent cylinder wake and spherical shock wave

K. Aruga, K. Inokuma, T. Watanabe, K. Nagata, Y. Sakai
Experimental investigation of interactions between turbulent cylinder wake and spherical shock wave
Physics of Fluids, 32 16101 2020

This article may be found at https://doi.org/10.1063/1.5128267.

The PDF is also available here.  
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. 

Abstract

Interactions between a spherical shock wave and a turbulent cylinder wake are studied with wind tunnel experiments. The shock wave is generated outside the wake and propagates across the turbulent wake. Instantaneous streamwise velocity is measured on the wake centerline while peak overpressure of the shock wave is measured outside the wake after the shock wave has passed across the wake. The experiments are performed for various conditions of the cylinder wake to investigate the influences of the root-mean-squared (rms) velocity fluctuation and of the length of the turbulent region through which the shock wave propagates. The velocity fluctuation opposite to the shock propagation direction is positively correlated with the peak-overpressure fluctuation. The mean peak overpressure decreases after the shock wave propagates in the wake. These relations between velocity and peak overpressure are explained by the shock-surface deformation, where the peak overpressure is increased and decreased, respectively, for the shock surfaces with concave and convex shapes in relation to the shock propagation direction. The correlation coefficients between the velocity and peak-overpressure fluctuations and the rms peak-overpressure fluctuation increase with the rms velocity fluctuation. The rms peak-overpressure fluctuation becomes independent of the turbulent length on the shock ray once the shock wave has propagated through a sufficiently long turbulent region. The peak-overpressure fluctuation has a probability density function (PDF) close to a Gaussian shape even though the PDF of velocity fluctuations in the wake is negatively skewed.

日本語訳 (DeepL翻訳)

乱流円柱後流と球形衝撃波の相互作用に関する実験的調査

球形の衝撃波と乱流円柱後流の相互作用を風洞実験により調査した。衝撃波は後流の外側で発生し、乱流後流を横切って伝播する。衝撃波の瞬間流速は後流中心線上で計測し，衝撃波のピーク圧力は衝撃波が後流を横切った後に後流の外側で計測する．後流の条件を変えて実験を行い，速度変動の二乗平均平方根と衝撃波が伝搬する乱流領域の長さの影響を調べた．衝撃波の伝播方向と反対側の速度変動は、ピーク圧力変動と正の相関があることがわかった。また，衝撃波が後流に伝播した後，平均ピーク圧力は減少する．これらの速度と圧力の関係は、衝撃面の変形によって説明される。衝撃面が衝撃の伝播方向に対して凹型と凸型の場合、圧力のピーク値はそれぞれ増加、減少する。速度変動とピーク圧力変動の相関係数とrmsピーク圧力変動は、rms速度変動が大きくなるにつれて大きくなる。衝撃波が十分に長い乱流領域を伝搬すると、rms peak-overpressure変動は衝撃波上の乱流長に依存しなくなる。後流の速度変動のPDFが負に偏っていても、ピーク圧力変動はガウス型に近い確率密度関数（PDF）を持つことがわかった。

GD