Turbulence under quasi-cavitating conditions: A new species?

This article presents measurements of turbulence fluctuations in an upscale d, two-dimensional model of a plain-orifice injector,,with and,without the presence of cavitation simulated by an air bubble. The measurements were ma de at different locations in the orifice cross section, and at different pl anes along the direction of the flow. Two-color laser Doppler velocimetry d ata allowed the calculation of Reynolds stresses as roell as turbulence pow er spectra. The results show that the turbulence in the presence of simulat ed or quasi-cavitation behaves quite differently from the case without cavi tation: it changes more radically with changes on the Reynolds number and s eems to be fairly independent of the magnitude of the Reynolds stresses. Th ese observations cannot be explained by using conventional shear-induced tu rbulence models. Experiments with forced cavity fluctuations show an increa sed receptivity at certain frequencies.