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Hot Wire Laboratory

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THE UNIVERISTY OF MANCHESTER SCHOOL OF MECHANICAL, AEROSPACE AND CIVIL ENGINEERING LABORATORY REPORT INSTRUMENTATION AND MEASUREMENT VORTEX SHEDDING FROM A CYLINDER & DATA ACQUISITION NAME: MANISH PITROLA STUDENT ID: 75050320 COURSE: MEng MECHANICAL ENGINEERING DUE DATE: 27TH NOVEMBER 2012 1) What are the main advantages and disadvantages of using a hotwire to measure flow velocities? There are many advantages and disadvantages of using a hotwire to measure flow velocities, one of the main advantages is the hotwire produces a continuous analogue output of the velocity at a particular point, and hence information about the velocity can be obtained for any specific time. Another advantage of using a hotwire …show more content…

However this can be overcome by averaging the FFT which allows us to easily identify peaks which can be seen from figure 10. 8) In this experiment, why are 2 frequency peaks seen on the FFT when the hotwire is near the centre line? 2 frequency peaks can be seen on the FFT at the centreline due to the 2 vortices induced by the cylinder but as you move away from the centre line only one of the vortices is predominant. The two peaks occur at 129Hz and 250Hz. 9) With increasing distance from the centreline, how does the FFT distribution change? Include graphs to illustrate this for various locations across the wake. From the below figures it can be seen that as you move away from the centre line the peaks in the FFT distribution disappear. Figure [ 11 ] Figure [ 12 ] Figure [ 13 ] Figure [ 14 ] Figure [ 15 ] Figure [ 16 ] 10) Plot the probability distribution histograms of velocity for various positions across the wake. What does the histogram show and how can the variation in the histograms be explained in terms of the properties of the flow? Figure [ 17 ] Figure [ 18 ] Figure [ 19 ] Figure [ 20 ] Figure [ 21 ] Figure [ 22 ] By comparing the above probability distribution figures it can be seen that with distance away from the centreline the flow velocity

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