JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV Year WIND TUNNEL TECHNIQUE Previous Question Paper (January/February - 2023 - R18)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
How to scale the values obtained from wind tunnel test to the actual model values?
Answer
Wind tunnel test data is scaled to full-scale values using Dynamic Similarity. This requires matching the non-dimensional parameters between the model and the prototype, primarily the Reynolds number (for viscous effects) and Mach number (for compressibility effects), ensuring that the flow physics remain consistent.
What are the merits and demerits of open circuit tunnel?
Answer
The merits of an open circuit tunnel include lower initial construction costs and the ability to test models that produce exhaust gases or smoke. The demerits include higher power consumption due to the loss of kinetic energy at the exit, sensitivity to ambient weather conditions, and increased noise levels in the surrounding environment.
State the working of expansion valve in hypersonic wind tunnel.
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Summarize the functions of Diffuser in a wind tunnel.
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Write a short note on tunnel blockage factor.
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Identify the techniques used for measurement of turbulence in wind tunnel.
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Write the relation between total, static and dynamic head.
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What is the technique adopted to visualize Shock waves.
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Give some disadvantages of Dial type Pressure gauge.
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Differentiate between free piston shock tunnel and expansion tunnel.
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Part B
Discuss the usefulness of Buckingham theorem in terms of identification of non-dimensional aerodynamic coefficients.
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What is geometrical similarity in wind tunnel testing of models? Explain.
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Is kinematic similarities different from dynamic similarities? Explain in detail.
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Explain the importance of dimensionless number in aerodynamics.
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Describe in detail the losses in supersonic wind tunnel.
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How are the wind tunnels classified? What are the special problems of testing in hypersonic wind tunnels?
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Differentiate between continuous supersonic type and continuous return type subsonic wind tunnel.
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Explain the process how wind tunnel is sized. How many different parameters are measured using wind tunnel?
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Explain how the velocity calibration done in subsonic wind tunnel test section.
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How are the surface streamlines and turbulence measured in wind tunnels?
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List and explain flow angularity measurements. Explain the necessity of measuring flow angularity parameters.
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Bring out the essential features of a strain gauge based six component internal wind balance.
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Compare the difference between Schlieren and shadowgraph methods for flow visualization.
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Illustrate the following methods related to wind tunnel flow velocity measurements: i) Intrusive method ii) non-Intrusive method.
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Explain particle image visualization. Write down how it differs from smoke visualization process.
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Discuss in detail fringe displacement method with neat sketches.
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Present the effects produced by the presence of the lateral boundaries in wind tunnel testing?
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Describe the importance of three degree of freedom manipulator used for store separation tests in wind tunnel.
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Explain the method of testing using Laser induced fluorescence over absorption spectroscopy.
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Classify various special types of wind tunnel techniques. Explain its characteristics.
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