Unsteady test technique of jet control with multi-parameter coupling

Abstract

In this paper, the jet control effect of air vehicle is studied, and a new multi parameter coupling unsteady test technique is established, which can ensure that the test model is consistent with the real air vehicle, and the jet is carried out under the condition of complete freedom and no support constraints, so that the wind tunnel test can better simulate the jet control effect of real air vehicle. The new technique overcomes the shortcoming that the previous jet test can only carry out unsteady flow field or unsteady aerodynamic force research, and can ensure that in the whole process of jet flow, the interference flow field at the nozzle, the aerodynamic force of the air vehicle, especially the movement of the air vehicle, are coupled with each other all the time, so as to achieve the same effect as the real air vehicle. The establishment of the new technique overcomes many problems, including the total length of the model is 167 mm, no support for the model, storage of small volume/high-pressure gas in free state, on-time unlocking of sealed gas source in free state of the model, and connection of gas source and nozzle in the model. The test results show that when no jet, the revolution body is head up, which affected by the cavity shock wave. When jet on, the jet force continues to act on the revolution body, resulting in the revolution body lowering its head until it diverges. The new technique can achieve more advanced technical indicators, including: ensuring jet Mach number >1; Ensure that the static pressure ratio of the jet is more than 10 (the static pressure ratio can be greater at hypersonic speed). After the establishment of the new technique, the supersonic wind tunnel test is carried out, and the ideal test results are obtained, which shows that the new technique is reliable.

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“…A novel technique suitable for wind tunnel measurements, with additional points of contact between the model and the support sting, is proposed in Vuković et al 8 It is reported that transient starting and stopping loads can be reduced by more than 50%, which enables achieving higher Mach numbers in the working section. Another interesting example of an enhanced wind tunnel measuring technique is described in Xue et al 9 on a case of a jet controlled air vehicles. The peculiarities here are that the model is completely free, not constrained by any additional support, because a small volume high-pressure gas cylinder is incorporated directly into the model of the air vehicle, which enables the investigation of changes in model’s attitude and orientation with jet both on and off.…”