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An Experimental Investigation of Unsteady Flow Over a Delta Wing in Supersonic Regime

Nazifi, Mohammad | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49164 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Soltani, Mohammad Reza
  7. Abstract:
  8. Focusing on unsteady flow field over delta wings due to vacuity of researches in this branch on one hand and requiring of modern aircrafts designers to this science on the other hand, expresses necessity of accomplishing present investigation. Scrutiny of pressure distribution of low aspect ratio wings in unsteady state and determination of aerodynamic characteristics of these wings in variant conditions, can be beneficial to plan aircrafts need to fly with high maneuverability in high speeds. This issue becomes important when in supersonic regime, with respect to emerged shock waves and vortices, develop complicated pressure distributions on the wing surface in unsteady state that affect aerodynamic behavior of the wing. For performing these experiments, a half delta wing was constructed and mounted to a half rectangular fuselage with parabolic noses on both sides. To create pitching oscillation, this model was equipped with an oscillator mechanism in which oscillation frequency was in a range from 2 to 6 Hz and oscillation amplitude adjusted so that maximum angle of attack the wing was placed in, was about 26 degree. These experiments were executed in tri-sonic wind tunnel of Qadr center at Imam Hussain (peace be upon him) university and in order to more accurate study of delta wing pressure distributions, the model was tested under static and dynamic conditions in free stream mach numbers 0.8 and 2.0. These experiments were pressure type in which pressure distribution of wing upper surface was measured by pressure holes were created in 5 sections on upper surface of the wing. Parameters that effects of their changes on surface pressure distribution was considered, included angle of attack, mach number, reduced frequency, mean angle of attack, and oscillation amplitude. The obtained results of these experiments illustrated the immense effect of wing angle of attack and free stream mach number on the wing surface pressure coefficients and location of wing vortex formation in static condition, and the considerable effect of reduced frequency on the hysteresis loops, slope of pressure distribution graphs, maximum wing suction, occurrence of vortex burst phenomenon, and wing dynamic stall in dynamic condition
  9. Keywords:
  10. Shock Wave ; Pressure Distribution ; Delta Wing ; Pitching Oscillation ; Unsteady Flow ; Supersonic Regime ; Vortex Burst

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