高重频激光减阻的关键因素选择方法研究

Selection Method of Key Parameters for Wave Drag Reduction by High Frequency Laser Energy

关键词:  高重频  激光能量  波阻  量纲分析  流动控制

Key words:  High frequency  Laser energy  Wave drag  Dimensional analyzing  Flow control

摘要:

针对影响高重频激光降低超声速波阻的因素多而复杂的问题，研究关键无量纲参数对减阻性能的影响规律，目的是揭示其影响新机理，提出其选择新方法。首先采用量纲分析的方法提炼影响高重频激光减阻的关键无量纲参数，然后通过求解N-S方程研究各个无量纲参数对减阻性能的影响规律以及它们之间的制约关系，并通过流动分析揭示其影响原因，最后提出无量纲参数的优化选择方案。结果表明:高重频激光减阻性能取决于无量纲激光能量大小、激光注入位置和来流马赫数；减阻百分比和能量效率与无量纲激光能量大小呈指数关系，与激光注入位置呈先上升后下降的关系，减阻百分比与马赫数呈指数关系，能量效率与马赫数呈先上升后下降的关系，在马赫6时能量效率达到14左右；激光能量大小和注入位置对减阻性能的影响密切相关，存在优化的激光能量大小和注入位置，随着能量的提高，优化位置由1.5逐渐提高至2.6左右，提高幅度逐渐减小。研究结果揭示了关键参数对高重频激光减阻性能的影响规律，提出了关键参数的选择方法。

Abstract:

The parameters for wave drag reduction by high frequency pulsed laser energy are multiplex. The effects of key non-dimensional parameters on wave drag reduction performance are studied in order to disclose new physical mechanisms of the key non-dimensional parameters and provide a new optimization method. Firstly，the key non-dimensional parameters are abstracted by dimensional analyzing. Secondly，influences of each of the key parameters and the relationships among them are studied by solving the N-S equations. Thirdly，the mechanisms of the influences are disclosed by the flow field distributions. Finally，the optimized selection method of the key parameters is suggested. The results indicate that performance of wave drag reduction depends on non-dimensional laser energy magnitude and depositing position and Mach number of the free stream. Drag reduction percent and power gain of laser energy are exponential with non-dimensional laser energy magnitude. It increases first then decreases with non-dimensional laser energy depositing position. Drag reduction percent is exponential with free stream Mach number. Power gain of laser energy increases to about 14 at Mach 6，and then decreases. The influences of non-dimensional laser energy magnitude and depositing position are tied up，and could be optimized. The optimized position increases from 1.5 to about 2.6 with the increasing of energy. The law of wave drag reduction performance influenced with the key non-dimensional parameters is disclosed，and optimization method is proposed.