Study of Key Non-dimensional Parameters for Wave Drag Reduction with High-Frequency Repetitive Laser Pulse Energy Depositions

Zexu Qing,Bin Zhang,Diankai Wang,Yanji Hong,A Sikora,S Wang,B Choi

doi:10.1051/matecconf/20167510001

Abstract

The problem of wave drag reduction with high-frequency repetitive laser pulse energy depositions is multivariable. Three key non-dimensional parameters, non-dimensional energy, non-dimensional depositing position and Mach number , were constructed from a number of original variables by using Buckingham pi theorem. Influences of these non-dimensional parameters on energy deposition performance, namely drag reduction and energy deposition efficiency, were investigated numerically by solving three-dimensional Navier-Stokes equations with an upwind scheme. Optimizing method of non-dimensional energy and non-dimensional depositing position is proposed. Drag reduction and energy deposition efficiency have exponential relationships with non-dimensional energy; Drag reduction and energy deposition efficiency have quadratic relationships with non-dimensional depositing position. Drag reduction has exponential relationship with freestream Mach number and energy deposition efficiency has quadratic relationship with Mach number. Non-dimensional laser energy and non-dimensional depositing position should be optimized synthetically for a given freestream.

Highlights

At the present state of art, realizing practicable hypersonic flight is hampered by great drag wave, which even accounts for more than half of total drag in some cases
A mitiagation of the bow shock accompanied by drag and heat flux reduction can be observed
Study conducted by Kim et al [3] shown that a drag reduction about 21% corresponding to energy deposition efficiency of ~10 could be obtained at Mach number of 1.92 utilizing the laser whose maximum frequency and power was up to 50 kHz and 400 W respectively

Summary

Introduction

At the present state of art, realizing practicable hypersonic flight is hampered by great drag wave, which even accounts for more than half of total drag in some cases. Experimental study of a single laser pulse energy deposition was performed over a sphere in a supersonic flow with Mach number of 3.45 by Adelgren et al [1]. Study conducted by Kim et al [3] shown that a drag reduction about 21% corresponding to energy deposition efficiency of ~10 could be obtained at Mach number of 1.92 utilizing the laser whose maximum frequency and power was up to 50 kHz and 400 W respectively. The drag reduction was proportional to the freestream Mach number under the constant energy deposition condition in Taguchi’s study. Parameters for wave drag reduction with highfrequency repetitive laser pulse energy depositions are so numerous, including laser energy magnitude, energy depositing position, Mach number, pressure and temperature of freestream, size and shape of the body etc., that it is necessary to construct key non-dimensional. Based on these key non-dimensional parameters, a series of numerical experiments were carried out and more general laws about the effects of these parameters on energy deposition performance were obtained

Dimensional analysis

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Computational methodology

Non-dimensional energy H

Findings

Summary