The diode array velocimeter

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Virginia Tech

A novel, point measurement, proof-of-concept laser velocimeter has been developed and tested. The diode array velocimeter (DAV) uses a single laser beam for its probe. The DAV measures velocity within a seeded, transparent medium by timing the passage of a seed particle’s image across an array of PIN photodiodes. This prototype device can measure one component of mean velocity as well as one component of time-averaged turbulence intensity. The concept for the DAV is rather simple. It also has an advantage over existing laser velocimeters in that it is relatively inexpensive.

Measurements made with the prototype DAV are compared to those made by a single hot-wire anemometer in a turbulent wall bounded flow with a freestream velocity of 10 m/s. The prototype DAV was found to be accurate to within 10% of Ue in mean velocity, and within 1.5% of Ue in turbulence intensity. The prototype DAV can measure mean velocities as great as 60 m/s. It has the potential for making measurements in highly turbulent reversing flows.