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Experimental Investigation of Buzz Frequency on an Axisymmetric Supersonic Air Intake Using Pressure Distribution on the Wind Tunnel Wall

Bagheri, Maryam | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46593 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Soltani, Mohammad Reza; Farahani, Mohammad
  7. Abstract:
  8. Supersonic intakes with mixed compression has an appropriate performance in the critical point, but in the subcritical performance, when inlet mass flow rate is reduced to a certain amount, a self-sustained instability occurs in the flow. In this case, instability appears in the form of shock waves system oscillation which is called Buzz phenomenon. An axisymmetric supersonic air intake with mixed compression which is designed for a Mach number of 2 has been investigated experimentally in order to study buzz frequency. The intake has been experimented in different Mach numbers, angles of attack and mass flow rates. Besides, the intake with wind tunnel wall has been modeled and analyzed in Fluent software in the steady state. Static pressure distribution on the wind tunnel wind and the model has been compared with numerical solution predictions using static pressure data on the different points of the wall and the model. Moreover, important characteristics of the buzz phenomenon such as amplitude and frequency of oscillations in different mass flow rates, Mach numbers and angles of attack have been obtained and compared with the ones on the several points of the model.
    Analysis of results during the Buzz phenomenon has shown a dominant frequency during the oscillations. In all mass flow rates, Mach numbers and angles of attack, the oscillations frequency of all wall points is equal to the oscillations frequency of the model points. But the oscillations amplitude of the model points is always bigger than the oscillations amplitude of the wall; and the oscillations amplitude is inversely proportional to the distance from the oscillations source. Furthermore, it has shown that oscillations frequency increases and oscillations amplitude decrease as the Mach number increases in these points; also, mass flow rate increasing leads to frequency and amplitude decreasing and angle of attack increasing causes the frequency increasing and the amplitude decreasing
  9. Keywords:
  10. Amplitude ; Attack Angle ; Mass Flow Rate Scaling ; Frequency Ranges ; Buzz Phenomenon ; Mach Number

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