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Experimental Investigation of Spin on Rotating Body at Supersonic and Transonic Flow

Askary Seyyed Lashkari, Farshid | 2021

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 54509 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Soltani, Mohamd Reaza; Farahani, Mohamad
  7. Abstract:
  8. One of the methods for the stability of the projectile is its rotation. The rotational velocity of the body surface induces velocity to the adjacent flow, thus changing the shape of the boundary layer, and due to the change in the thickness distribution of the boundary layer, the effective aerodynamic shape of the body also changes, which causes a force perpendicular to the angle of attack.This effect is called the Magnus effect. Since the force created by the rotation is an undamped force, the possibility of dynamic instability is very likely. There is no comprehensive analytical method that can accurately calculate its value for a wide range of projectiles.Due to the effect of Magnus coefficients from various parameters and the existence of little experimental data, it is difficult to understand the effect of important parameters on this phenomenon. On the other hand, due to the small amount of Magnus force versus normal force (about 0.1 to 0.01), experimental measurements are very difficult and a large dispersion is observed in the experimental results.In this investigation, by a new technique, pressure distribution on a rotating body and subsequent distribution of Magnus force has been obtained. For this investigation, a 16-bit data logger system was designed and built and located inside the rotating model along with the battery, sensors and storage. A special mechanism was designed and built to rotate the model up to 5000 rpm. Experiments were performed in three Mach 0.4, 0.8 and 1.6 and in attack angles from zero to 25 degrees. The pressure distribution on the model, shows that the maximum amount of Magnus force is produced at the end of the body and the place of shock and its interference with the boundary layer is very effective on this distribution. The maximum local magnitude of the Magnus force at Mach 0.4 occurs at a position closer to the end of the body than at Mach 0.8
  9. Keywords:
  10. Pressure Distribution ; Wind Tunnel ; Magnus Force Coefficient ; Rotating Body ; Projectile

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