On Estimation of Direction in which Shock Propagates

Abstract

This paper focuses on a sensor, which provides information of a shock propagating in flow field such as strength and direction of the shock. In engineering practice of aerospace, automobile, manufacture and so on, the shock wave is formed in high-speed flow and its strength and shape affect the flow properties behind the shock, and finally are responsible for efficiency of manufactured products and productivity of industrial goods. In this study, a sensitive head of a pressure transducer, on which a semi-conductor type strain gauge is glued, is analyzed using FEM and the relation is discussed between the behavior of its diaphragm over which a shock passes and the direction in which the shock is travelling. The numerical analysis offers that the strain distribution of surface of the diaphragm depends on the shock direction and that the direction of maximum principal strain of the diaphragm corresponds to the shock direction or its perpendicular direction. Experimentally, the strains in different directions on the diaphragm are obtained and the direction of maximum principal strain is estimated using Rosette analysis, being compared with the shock direction. As a result, it is possible to estimate the shock direction with adequate accuracy, using a scheme proposed in the present paper.