Thrust Measurement of a Rectangular Hypersonic Nozzle Using an Inclined Baffle Plate

Abstract

Thrust measurement of a rectangular hypersonic nozzle employed in the precooled turbojet engine under development in the JapanAerospace Exploration Agency is carried out using an inclined baffle plate. A 1.0%-scaled model of the nozzle was manufactured, and its gross thrust was investigated. The hypersonic nozzle has a variable throat and an external ramp to compensate the drastic change in the nozzle pressure ratio through the operation. At takeoff, an intensive jet noise is expected due to the high-speed exhaust jet, and in the present study, the impact of aerodynamic-tab jet noise suppressors on the thrust vector of the nozzle is investigated. Because of the simplicity, a baffle plate, which basically provides an on-axis forcemeasurement, is applied to a simultaneousmeasurement of the magnitude andangle of the thrust vector by giving anangle to the impact surface relative to the jet. It is shown that the magnitude of the thrust vector is kept constant regardless of the aerodynamic-tabmass fraction, which implies that a lossless mixing between the main jet and aerodynamic tab can be assumed. It is also shown that the thrust angle changes with the increase in the aerodynamic-tab mass fraction because of the deformation of the jet cross section.