Combining LDA and PIV for turbulence measurements in unsteady swirling flows

Combining LDA and PIV techniques to investigate unsteady swirling flows permits a more detailed interpretation of velocity fluctuations than that from LDA alone. This can be necessary when comparing measurements with numerical simulations which attempt to capture the unsteadiness. One possible method of combining the measurement data is introduced and discussed with application to swirling flowfields which exhibit a precessing vortex core. The analysis indicates that in such flows the unsteadiness accounts for up to 70% of the total energy in the velocity fluctuations.