Active Control of an Axisymmetric Turbulent Jet Using Moving Delta Tabs : (Effects of the Delta Tabs Oscillating in Phase)

概要

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For the development of an active control of a turbulent jet, measurements of an axisymmetric turbulent jet were performed with multiple “moving delta tabs.” Five computercontrolled delta tabs, which can be driven independently, were installed at the skimmer. Two modes were tested; in the first mode, all the delta tabs were stationary (i.e., conventional way), and in the second mode, the delta tabs were oscillated in phase at a frequency of 4 Hz. Simultaneous multipoint measurements of instantaneous velocity were performed using a rake of 21 I-type hot wires, specially designed and manufactured for this study. The results are compared with those in a canonical axisymmetric jet without tabs. The results show that the turbulence quantities, such as mean and rms velocities, skewness, kurtosis, probability density function, and power spectra are significantly altered by the stationary and oscillating delta tabs. The effects of the oscillation of delta tabs are found to modify the large-scale structure in the near field of the jet. The results confirm the effectiveness of the active control of an axisymmetric jet using the oscillating delta tabs.