An investigation into the use of Cross Correlation Velocimetry

This study analyses the applicability of cross correlating the signal between two thermocouples to obtain simultaneous measurement of velocity, integral turbulent length scales, and temperature in fire induced turbulent flows. This sensor is based on the classical Taylor\u27s hypothesis which states that turbulent structures should retain their shape and identity over a small period of time. If sampling rate is fast enough such that the signal from two thermocouples is sampled within this time duration, the turbulent eddy can be used as a tracer to measure flow velocity and fluctuation. Experiments performed in two laboratory scale devices: a heated turbulent jet and a variable diameter natural gas burner show that sampling rate, sampling time, and angular orientation with respect to the bulk flow are the most sensitive parameters in velocity measurements. Flows with Reynolds numbers between 300 (u=0.1m/s) and 6000 (u=2.0 m/s) were tested