SIMULTANEOUS MEASUREMENTS OF VELOCITY AND PRESURE FLUCTUATIONS IN TURBULENTFLOWS

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(1) The combined probe consisting of pressure and X-type hot-wire sensor was developed to measure velocity and fluctuating static-pressure simultaneously in turbulent flows. The systems for the automatic measurement and the high-speed date-processing were developed.(2) The probe was applied to the measurement of the circular jet excited at Strouhal number St = 0.82 in order to regulate the vortex motion in the jet. Using the acquired date, the terms of convection, turbulence diffusion, pressure transport and production of the turbulence energy transport equation were estimated, and turbulence energy budget were discussed in relation to the turbulence structure. The result shows the reliability of the developed probe. In particular it is a significant result of the present study that the term of pressure transport was estimated experimentally.(3) In the axisymmetric mixing layer, the pressure transport (velocity-pressure correlation) was estimated and discussed in relation to the vortex motion. The turbulence models used in the turbulence-energy transport equation and the Reynolds-street transport equation were discussed by the experimental data. The result reveals that the models are not satisfied in the region where the large-scale vortex motion dominates. The result is useful to improve the turbulence models.(4) The sound sources of circular and rectangular jets were discussed focusing on the vortex motions detected by the pressure measurements. The sound sources were estimated by the second time-derivatives of fluctuating static-pressure. The result indicates that the sources are related to pairing and cut-and-connection of vortices.