ノズル形態が極超音速航空機の離陸騒音に及ぼす影響

抄録

Effect of nozzle configuration on the takeoff noise of a hypersonic transport is investigated based on small-scale nozzle experiments. In the Japan Aerospace Exploration Agency, the precooled turbojet (PCTJ) engine aimed at the hypersonic flight is under development. The takeoff noise of the full-scale vehicle is assessed before it is put into the operation using an acoustic simulation method. By matching the jet velocity and jet Mach number with the realistic PCTJ engine condition, the acoustic characteristics of the hypersonic nozzle are duplicated with a small-scale nozzle model. The jet noise database around the hypersonic nozzle is established through a number of experiments, and by taking into account 1) the nozzle scale, 2) the number of nozzles, 3) the direction of installation, 4) the measurement distance and angle based on the flight trajectory, and 5) the atmospheric absorption, the effective perceived noise level (EPNL) at the flyover point is calculated. It is shown that the nozzle configuration has a large impact on the takeoff noise, and that such an assessment could contribute to the improvement of the integration design of the vehicle.