フリップフロップ・ジェット・ノズルの発振周波数について

Abstract

This research deals with the oscillation frequency of a flip-flop jet nozzle based on the measurements of pressure and velocity in a connecting tube. The trace of pressure difference between both the ends of the connecting tube is simply modeled by a triangular wave, and the velocity in the connecting tube is calculated by the method of characteristics and the Runge-Kutta method. The authors assume that a jet switches when the integral J(sub M), J(sub K), or J(sub P) reaches a threshold value, where J(sub M), J(sub K), and J(sub P) are the accumulations of momentum, kinetic energy and mass which are transported through the connecting tube from a side wall with higher pressure into another side wall with lower pressure, respectively. As a result, J(sub P) is the most adequate among the three. The Strouhal number calculated on the basis of J(sub P) agrees well with experimental one.