飞翼布局无人机双S弯进气道设计及流动控制技术应用研究

发布时间：2018-07-10 05:13

本文选题：S弯进气道 + 二次流　；参考：《南京航空航天大学》2016年硕士论文

【摘要】：基于飞行器对隐身性能及重量的要求,双S弯进气道往往设计成偏距较大,长度较短的形状。然而大偏距、短扩压式双S弯进气道由于弯度较大,产生的二次流强度较强,容易引起附面层分离,这将严重影响航空发动机的稳定性。针对这一问题,本文展开了以下几个方面的研究:(1)研究了双S弯进气道造型特点,参考国内外复杂截面进口形状进气道的设计方法,采用半径过渡的方法实现了双S弯进气道三维造型的参数化设计。(2)分析了双S弯进气道内二次流生成机理以及二次流的发展,研究了中心线变化规率、面积变化规律以及双S弯进气道第一、二S弯长度比例对进气道气动性能的影响。通过数值模拟分析得出,中心线变化规律、面积变化规律以及双S弯进气道第一、二S弯长度比例都是通过影响进气道壁面沿程压力梯度分布来影响进气道气动性能;中心线变化规律选取缓急相当与缓急相当配合,面积变化规律选取前急后缓与前缓后急的配合,第一、二S弯比例选取0.77,双S弯进气道的气动性能最佳。(3)在传统双S弯进气道设计的基础上,本文着重研究了双S弯进气道第一、二S弯进气道的交界面形状对进气道内二次流的影响,并提出通过优化设计交界面形状来削弱双S弯进气道内二次流强度,抑制附面层分离的设计方法。通过分析得出,在保证双S弯进气道交界面面积相同条件下,交界面高度选取进气道进口高度,形状选用带倒圆矩形形状能够有效削弱交界面处二次流强度,抑制附面层分离。(4)分析了飞行器飞行Ma、攻角、侧滑角以及发动机流量变化对双S弯进气道气动性能的影响。通过数值仿真分析得出,飞行器飞行Ma、攻角、侧滑角通过影响进气道进气品质影响进气道性能,发动机流量变化则是通过影响进气道内流动速度影响进气道气动性能。(5)研究了脉冲射流射流频率、射流流量对进气道附面层分离控制效果的影响,应用FFT方法分析了脉冲射流控制机理,并对比了脉冲射流与定常射流的控制效果。通过数值模拟分析得出,在射流频率与脱落涡频率相同时,射流控制效果最好。射流流量影响着脉冲射流控制效果,射流流量增加到一定程度时,脉冲射流对总压恢复系数的提升逐渐减小。
[Abstract]:Based on the requirements of stealth performance and weight of aircraft, the double S curved inlet is usually designed into a shape with large distance and short length. However, due to the large deviation and short diffuser double S-bend inlet, the secondary flow intensity is stronger and the boundary layer is easy to be separated, which will seriously affect the stability of the aero-engine. In order to solve this problem, the following aspects are studied in this paper: (1) the modeling characteristics of double S curved inlet are studied, and the design method of inlet with complex cross section at home and abroad is referred to. The parametric design of three dimensional modeling of double S curved inlet is realized by using the method of radius transition. (2) the mechanism of secondary flow generation and the development of secondary flow in double S curved inlet are analyzed, and the variation gauge rate of center line is studied. The effect of area variation and the ratio of the first and second S-bending length on the aerodynamic performance of the inlet. Through numerical simulation analysis, it is concluded that the variation law of center line, the law of area change and the ratio of the first and second S-bending length of the double S-bend inlet affect the aerodynamic performance of the inlet by influencing the pressure gradient distribution along the inlet wall. The law of change of the center line selects the matching between the priority and the priority, and the law of area change selects the cooperation between the front and the back and the front and the back. First, When the ratio of two S-bending is 0.77, the aerodynamic performance of double-S-bend inlet is the best. (3) based on the traditional design of double-S-bend inlet, this paper focuses on the study of the first double-S-bend inlet. The influence of the interface shape of the two-S-bend inlet on the secondary flow in the inlet is discussed. The design method of reducing the intensity of the secondary flow and restraining the separation of the boundary layer by optimizing the shape of the interface is put forward. Through analysis, it is concluded that under the condition that the interface area of double S curved inlet is the same, the inlet height is chosen as the interface height and the rectangular shape with inverted circle can effectively weaken the secondary flow intensity at the interface. Suppression of boundary layer separation. (4) the effects of flight angle, attack angle, side slip angle and engine flow rate on the aerodynamic performance of double S curved inlet are analyzed. The numerical simulation results show that the performance of the inlet is affected by the influence of the inlet quality on the flight MaA, attack angle and sideslip angle of the aircraft. The change of engine flow rate affects the aerodynamic performance of the inlet by influencing the flow velocity in the inlet. (5) the influence of the frequency of the pulse jet and the flow rate of the jet on the control effect of the inlet boundary layer separation is studied. The control mechanism of pulse jet is analyzed by FFT method, and the control effect between pulse jet and steady jet is compared. The numerical simulation results show that the jet control effect is the best when the frequency of jet is the same as the frequency of shedding vortex. The jet flow rate affects the control effect of the pulse jet. When the jet flow rate increases to a certain extent, the increase of the total pressure recovery coefficient of the pulse jet decreases gradually.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V279

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