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针对冲压发动机尾喷口动力学设计需求,采用试验测试与数值计算相结合的手段,对其固有模态和振动环境特征进行了研究,进而对其振动设计进行了评估。结果表明,尾喷口在2 kHz频率范围内,具有丰富的固有频率成分,振型表现为整体或前端局部的壳式振动;在燃烧室出现燃烧振荡后,尾喷口将增加78.125 Hz的窄带激励能量及其倍频成分;燃烧振荡激励的3、4、7倍频分别与尾喷口的第1、2、3阶固有频率接近,可能引起结构的共振,在实际工作中应给予充分重视。
According to the dynamic design requirements of the ramjet nozzle, the inherent modal and vibration characteristics of the ramjet engine were studied by the combination of experimental test and numerical calculation. Then the vibration design was evaluated. The results show that the tail nozzle has a rich natural frequency component in the frequency range of 2 kHz, and the mode shape manifests itself as a global or frontal shell vibration. When the combustion chamber oscillates, the tail nozzle will increase the narrow band excitation energy by 78.125 Hz And their frequency doubling components. The 3rd, 4th, and 7th harmonic frequencies of the combustion oscillation excitation are close to the natural frequencies of the first, second and third order of the nozzle orifice, respectively, which may cause resonance of the structure. In practice, sufficient attention should be paid.