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Experimental Investigation on the Effects of Angle of Attack on Supersonic Intake

Mostoufi, Keivan | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50740 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Soltani, Mohammad Reza
  7. Abstract:
  8. Twin intake is a new version of intakes for supersonic fighters with high performance. Investigations on these types of intakes show that with some modifications in design procedure and modifying the desired parameters, one could result in an intake compatible with the body and nose of the fighter with high efficiency. In this investigation the results of experiments on a supersonic air intake which is designed for 1.7 Mach number at angles of attack ranging from -4 to +6 degrees are presented. The main goal of this investigation is to analyze the effect of angle of attack on the performance of the intake in design and off-design conditions. In order to reduce the boundary layer thickness entering the intake, a compression surface is used at the entrance area which by providing a high pressure zone in front of the intake prevents the low momentum boundary layer from entering the air intake which spills some of the flow from the corners of intake resulting a higher performance. In addition, by using an isentropic-conical shock structure in front of the intake, pressure recovery value increased up to 87% which is so important for a supersonic air intake. Investigations on the static pressure distribution on different model's surfaces such as nose, cowl, compression surface and etc., show that differences in pressure distribution with respect to angle of attack in each part of the model is different from the other. For most of model parts, the static pressure on the surface will increase by the change in shock structure on the nose and intake's entrance area as the angle of attack increases. But, pressure distribution on the cowl has shown that by increasing the absolute value of angle of attack, the pressure value will increase on the cowl and this increase is higher for negative angle of attacks compared to positive angle of attacks. By measuring the total pressure distribution at the model exit plane, it could be obtained that the flow inside the intake duct has a negative velocity angle and at angle of attack 4 (deg), shows a zero angle of attack for velocity distribution at the inlet of the engine. In addition, by increasing the angle of attack, two high velocity vortical flows move toward the bottom of the intake exit plane. In general, reduction in the angle of attack to negative values will result in total pressure recovery and also increase the flow distortion
  9. Keywords:
  10. Supersonic Intake ; Attack Angle ; Flow Distribution Pattern ; Total Pressure Recovery

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