Sivells方法在高马赫数低总压喷管设计中的适用性分析

Applicability analysis of Sivells' method in nozzle designwith high Mach number and low total pressure

  • 摘要: 目前高超声速轴对称型面喷管广泛采用Sivells方法进行无黏型面设计,通过求解轴对称的von Kármán动量方程进行边界层修正。该方法在常规高超声速风洞、激波风洞等的高马赫数、高总压条件下已成功应用,但鲜有在高马赫数、低总压条件下的应用研究。在低总压条件下,采用该方法设计了马赫数6、8、10、12的轴对称型面喷管,通过数值模拟分析流场结构,并进行试验验证;模拟了喷管射流流场,通过对射流流场进行结构分析,判断设计方法的适用性。研究结果表明:马赫数6、8喷管流场与设计基本一致,射流流场品质较好,适合开展风洞试验;马赫数10、12喷管流场局部过度膨胀,马赫数高于设计值,其中马赫数10喷管的射流流场品质较好,马赫数12喷管的射流流场品质下降显著且马赫数轴向梯度增大。因此,在高马赫数、低总压条件下,Sivells设计方法仍适用于马赫数6、8喷管,马赫数10喷管处于临界状态,而不适用于马赫数12喷管。

     

    Abstract: At present, the Sivells' method is widely used for the design of the inviscid hypersonic axisymmetric nozzle contour. And then, the nozzle contour viscous correction is performed by solving the axisymmetric momentum equation. This design procedure is validated by nozzles in conventional hypersonic wind tunnels and shock wind tunnels, which are operated under high Mach number and high total pressure conditions. Meanwhile, there are few validation studies of this procedure under high Mach number and low total pressure conditions. In this study, the nozzle design procedure based on the Sivells' method is used for Mach 6, 8, 10, and 12 nozzle contour design under the low total pressure condition. Furthermore, in order to analyze nozzle flowfields, numerical simulation and wind tunnel experiment are carried out. It can be found that, the flowfields in Mach 6 nozzle and Mach 8 nozzle are consistent with expectation and the jet flowfields are so good that are suitable for test. In contrast, there are some over-expanded areas in the flowfields of Mach 10 nozzle and Mach 12 nozzle, which results in higher Mach number than expectation in those areas. The jet flowfield quality of Mach 10 nozzle is better than that of Mach 12 nozzle. It can be concluded that, under the condition of low total pressure, the Sivells' method still works well for Mach 6 nozzle and Mach 8 nozzle design. Meanwhile, the method is less effective when applied to the Mach 10 nozzle and Mach 12 nozzle design.

     

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