EXPERIMENTS ON THE CONTROL OF PLANE JETS BY AUXILIARY FLOWS

摘要

The operation of certain types of fluid flow devices depends upon the character and response of jet flows to applied disturbances. In such devices it is typical for a power jet to be deflected by a laterally impinging control jet, either in a steady or dynamic regime. Two-dimensional jet flows relevant to these devices are studied experimentally as a separate element, i. e., free from the effects of nearby solid boundaries.nSteady deflection characteristics for several jet geometries are dis-cussed and illustrated by photographs. For a single control jet system, flow measurements show a linear relationship between the momenta of the two interacting jets for constant angles of deflection. Analytical expressions which describe the deflection angle and resultant pressure forces in terms of the jet momenta are developed. For two symmetrically placed control jets, it is found that there exists a particular setback of the jet housings where control flow requirements are minimum. The problem of deflection past a wedge centered in the power jet stream is also considered.nDynamic studies include geometries with and without a wedge present. For moderate disturbances to the free jet, it is found that neutral stability persists at a Strouhal number of about 0.5. Some observations are included for dynamic traverse of the jet past a wedge and also self-excited oscillations' with a wedge present.