双喉道推力矢量喷管内外流特性
Flow Characteristics of Dual Throat Thrust Vectoring Nozzles
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摘要: 对二元双喉道推力矢量喷管内流特性进行了研究。针对一种简化的飞机后体模型,利用数值计算与风洞试验结合的方法研究了后机身一体化设计对矢量喷管内外流特性的影响,进一步分析了矢量喷流干扰效应对飞机后体的影响。研究结果表明,气流在喷管空腔内的分离导致了喷管上下壁面的压力差,而该压力差是双喉道喷管推力矢量产生的主要原因;随着二次流流量的增加,喷管上下壁面压差逐渐变大,喷管推力矢量角增加。无来流时,在主喷管落压比NPR=4.0,二次流落压比NPRs=4.8时,双喉道喷管具有的最大矢量角为16.6°;在来流Mach数Ma=0.4时,具有的最大矢量角为11.2°。喷管外罩表面声载荷频率主要集中在900 Hz以下,并且外罩型面变化剧烈处具有最高的噪声幅值。喷流矢量角的变化对噪声峰值频率没有影响,仅对下壁面1 000 Hz以下幅值有影响,噪声最大频谱幅值影响量为2 dB。Abstract: The investigation was conducted to investigate the flow characteristics on the dual throat thrust vectoring nozzle. Based on a simplified aircraft afterbody model, the numerical calculation and the wind tunnel test were carried out to study the effect of the integrated design of aircraft afterbody on the flow characteristics. The impact of the main flow/vectoring jet flow interaction on the aircraft afterbody was further investigated. The results indicate that, the difference between the upside and downside wall pressures is the main reason for the generation of thrust vectoring, and this difference is created by the separated turbulent flows in the cavity. The wall pressure difference increases with the enhancement of the secondary injection flow rate. Then the thrust vector angle of nozzle increases. The thrust vector angle reach the peak value 16.6° without outflow at the conditions that the primary NPR=4.0 and the secondary NPRs=4.8. While the peak thrust vector angle is 11.2° with outflow Ma=0.4. The dominant frequency of noise created from the nozzle cowl is within 900 Hz. The peak noise is located at the cowl configuration which changes sharply. The variation of the vectoring jet angle has no effect on the peak noise frequency, but only affects the amplitude below 1 000 Hz on the downside of nozzle cowl, and the influence of the maximum frequency spectrum amplitude is 2 dB.