Investigation on Noise Radiation Characteristics of Two-Phase Multi-Cycle Pulse Detonation Engine

Abstract

The noise radiation characteristics of single pulse detonation combustor (PDC) and hybrid pulse detonation engine (HPDE) were investigated under several operating frequencies, different equivalence ratio and fill fraction, while gasoline and air were selected as fuel and oxidizer. It is found that the noise radiation characteristics are intermittent and periodic. Pulse detonation engine jet noise are mainly consisted of annuploe source and quardrupole source. The frequency spectrum of the noise is very broad, its radiation energy mainly concentrates in the frequency range of 0-5 kHz, and it is composed of principal frequency (namely the detonation frequency), which is caused by pulse jet and harmonic frequencies. The peak sound pressure level is not sensitive to operating frequencies of this two kinds of conformations, but it increases along with the increasing of equivalence ratio and fill fraction. The impulse sound pressure level increases with the increasing of operating frequency, equivalence ratio and fill fraction . The peak sound pressure level of HPDE is less than PDC about 4dB, and the impulse sound pressure level reduces 2dB. At the same measuring locations, the head pressure, pipe pressure and PDC outlet pressure of the HPDE is greater than PDC. In the condition of HPDE’s equivalence ratio is a constant, when the detonation wave flows through the turbine, the reduction of the peak pressure between the PDC outlet and the turbine exhaust decreases with the increasing of fill fraction, and the greater fill fraction increases, the smaller reduction produces. The reduction is 29.74dB when fill fraction is 1.0.