AE2353 Wind Tunnel Techniques Anna University question bank

AE2353 Wind Tunnel Techniques Anna University question bank, previous year question paper and important 2marks and 16 marks questions PART – A Answer All the Questions

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1. Define Reynolds number? 2. Define Mach number? 3. What is meant by subsonic and transonic speed regime? 4. Define critical Mach number? Name any two equipments used in the calibration of wind tunnels. 6. What is meant by LDA? 7. What is meant by PIV? 8. Name any two equipments used for the measurement of force? How are the surface streamlines and turbulence measured in wind tunnels? 10. What is the technique adopted to visualize Shock waves. PART – B

(5 x 16 = 80) Answer All the Questions

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Explain the Buckingham’s Pi Theorem. (or) 12. Briefly discuss the scale effects of similarities. 13. Discuss the classification of wind tunnels in detail. (or) 14. Explain with a neat diagram the layout of a subsonic wind tunnel. Explain the techniques used for Turbulence measurements in a wind tunnel. (or) 16. Explain in detail the calibration of a supersonic tunnel. 17. Explain with a neat sketch the working of a hot wire anemometer. (or) Briefly explain the measurement of pressure, velocity and force in a wind tunnel. Discuss the smoke and tuft grid techniques used for flow visualization. (or) 20. Briefly explain the optical methods used for flow visualization. PART - A

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(10 X 2 = 20) Answer ALL the Questions 1. Explain the term dynamic similarity. 2. Define Mach number. 3. Define laminar and turbulent flow. 4. What are the classifications of wind tunnel? Name any two equipments used in the calibration of wind tunnels. Define horizontal buoyancy. 7. What is meant by LDA?

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Name any two equipments used for the measurements of velocity. How are the surface streamlines and turbulence measured in wind tunnels? What is meant by PIV? PART – B (5 x 16 = 80) Answer All the Questions Explain the Buckingham’s Pi theorem. (or) Explain the dynamic similarity between a wind tunnel model and the prototype to be flighttested. What are the essential conditions to be satisfied for the results to be carried from the model to the prototype? Are there any limitations or preconditions involved? What is understood by the term low speed wind tunnel in aerodynamic testing? Describe with brief details through sketches and plots, various types of low speed wind tunnels based upon the details of the flow in test section. (or) Write notes on: (a) setting Mach number in a transonic wind tunnel (b) Measurements of turbulence level in a transonic wind tunnel. Explain the techniques used for turbulence measurements in a wind tunnel.

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Describe the basis for the measurement of pressure and instruments used for the purpose. What are its advantages and applications? Illustrate with theory and an example. It is desired to obtain pressure distribution of a rotating circular cylinder kept in the test section of a wind tunnel. (or) 16. Explain in detail the calibration of a supersonic wind tunnel.

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Explain with a neat sketch the working of a hot wire anemometer. (or) What types of wind tunnel balances are used to ascertain forces and moments on an airplane model in a low speed wind tunnel? Hence describe the underlying principles of an external type wind tunnel balance for measuring lift, drag and pitching moments over a finite span wing.

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Explain the phenomenon of separation of flow over a 2D wing with the help of liquid paraffin generated smoke wire technique with good sketches. What are its merits over kerosene generated smoke? (or) Briefly explain the optical methods used for flow visualization. PART – A (10 x 2 = 20) Answer All the Questions 1. What is geometrical similarity in wind tunnel testing of models? What is boundary layer correction in the test section design of wind tunnels? 3. What is turbulence factor of a subsonic wind tunnel? How is test section speed measured in case of a subsonic wind tunnel? 5. How are wind tunnel balances classified? What is the basic principle involved in the interferometer method of flow visualization?

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7. What are the advantages of flow visualization methods? How is total pressure estimated in the test section of a super sonic wind tunnel? What is horizontal buoyancy? What are the limitations of dye injection method for flow visualization? PART – B (5 x 18 = 60) Answer All the Questions (a) State Buckingham theorem. How is thus theorem useful in the experiments using wind tunnels? (b) What is the basic principle behind hot wire anemometer? What are its limitations? (or) Define the following non-dimensional numbers: force coefficient, Euler number, Reynold’s number and moment coefficient. How do the model scale effects influence the wind tunnel test results? How are the wind tunnels classified? What are the special problems of testing in hypersonic wind tunnels? (or) Sketch the typical layout of a supersonic wind tunnel and mark all the components and subsystems. What is starting problem in supersonic tunnels? 15. Write short notes on the following topics: (a) Flow angularities in wind-tunnel testing. (b) Turbulence intensity measurements in wind tunnel test section. (or) With a neat illustration explain the objective of calibration of a wind tunnel. In what way the calibration procedure for a supersonic tunnel different from that of a subsonic wind tunnel? Distinguish between internal and external wind tunnel balances. Briefly explain how force measurements are carried out using an external strain gauge balance. (or) Bring out the essential features of a strain gauge based six component internal wind balance. Explain how the six components are measured using the balance. With neat illustration explain the basic principles of Schelieren method of flow visualization. What are the advantages and limitations of the method? (or) Write short notes on the following techniques: (a) Smoke technique for flow visualization. (b) Use of tufts and electrical techniques for flow visualization studies. Read more: http://thelecturernotes.blogspot.com/2010/12/ae2353-wind-tunnel-techniquesanna.html#ixzz1GD5xT8vr