Mean and turbulent velocity measurements in a turbojet exhaust

Laser Doppler velocimeter measurements have been conducted in a round high-speed high-temperature jet exhausting from a small-scale turbojet propulsion engine. The experiments were carried out in the exhaust of a turbojet propulsion engine specifically designed as a power unit for small aircraft. The authors present a survey of the jet flow field at Mach numbers of 0.46, 0.67, and 0.84 as well as the spectral analysis of the velocity fluctuations. In good agreement with the results obtained in isothermal jets, the radial distributions of the mean and root-mean-square velocities can be approximated by universal profiles. The spectra of the fluctuations exhibit a pronounced narrowband peak, providing evidence for the existence of coherent structures in the jet flow