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# System prepended metadata

title: Sample questions

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# Sample questions

1. Design an experiment to measure average drag from a solid sphere in a wind tunnel (i.e. the solid sphere and the wind tunnel are available to you): (a) Identify the sensors (type, number of sensors, location), instrumentation (such as amplifiers, signal conditioning), data acquisition (sampling rate, resolution for each sensor/instrument, length of data to capture); (b) Having identified the setup, draw a schematic of the setup showing the sample, wind tunnel and clearly show the positioning of your instruments with respect to the sample and connections to data acquisition. (c ) Outline the methodology of processing the acquired sensor output to get drag as the output. (d) Identify steps involved in the experiment (calibration, experiments to be performed).

2. (a) Explain the relevance of frequency-shifting (Bragg cell) in LDA. (b) List components of a generic LDA setup to be used for measuring 3 velocity components and the relative orientation of the corresponding measurement volumes.

3. Derive the expression for average and instantaneous velocity components from a three-wire hot wire probe.

4. Explain frequency response and its effect on measurements. Include graphical explanation. Plot frequency responses of generic hot wire anemometers and identify how they will affect measurements.

5. Draw schematics to explain the z-type Schlieren setup and the Mach-Zehnder interferometer (infinite fringe setting). For the Mach-Zehnder interferometer, derive the relation between fringe spacing and optical path length difference (see Goldstein for details).

6. Provide details of experiments to obtain the thermal conductivity of an alloy. Focus on rig design and instrumentation.