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Experimental Investigation of Buzz Phenomenon Suppression in a Supersonic Air Intake

Sepahi Younsi, Javad | 2015

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 47220 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Soltani, Mohammad Reza; Farahani, Mohammad
  7. Abstract:
  8. The buzz phenomenon is the shock oscillation ahead of the supersonic air intake when its mass flow rate is decreasing at subcriticaloperating condition. This phenomenon may cause combustion extinguishing, thrust loss and structural damages. To delay the buzz onset and reduce the amplitude and frequency of the buzz oscillations, the method of boundary layer suction has been proposed and studied in this research. The intake has been designed for a freestream Mach number of 2.0, however, wind tunnel tests have been conducted for freestream Mach numbers of 1.8, 2.0, and 2.2. All tests were performed for zero degrees angle of attack. For studying effects of the parameters of boundary layer system, eight tip cones have been fabricated and tested. Effects of the bleed entrance position, angle, and width as well as the effects of the exit area of the bleed duct on the performance and stability of the intake have been investigated by these cones. Total pressure recovery, mass flow ratio, flow distortion, and bleed mass flow ratio are selected as the intake performance quantities. Stability of the intake is also studied using the amplitude and frequency of the buzz oscillations and intake stability margin as the stability parameters. Results show that there is a strong relation between the acoustic characteristics of the intake and the buzz fluctuations. Applying the bleed causes a significant improvement in the intake performance as well as in delaying the buzz onset and reducing the buzz amplitude. Reducing the bleed entrance width and angle improve the intake performance, however, they anticipate the buzz onset and increase the amplitude of the buzz oscillations
  9. Keywords:
  10. Boundary Layer Suction ; Buzz Phenomenon ; Little Buzz ; Mixed Compression Supersonic Intake ; Big Buzz

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