Based on theory proposed in the preceding paper [3]. the numerical calculation and eVerimental study of sound absorption by pseudostochastic diffusors are carried out in this paper. Average specific acoustic impedance...Based on theory proposed in the preceding paper [3]. the numerical calculation and eVerimental study of sound absorption by pseudostochastic diffusors are carried out in this paper. Average specific acoustic impedance of the whole structure is obtained. The nonlinear coupling specific resistance is emphatically analysed. The experiments of measuring normal absorption coefficient of the structure are made. The tested results agree with predicated data.展开更多
In this paper,a new theory about sound absorption by pseudostochastic diffusors is proposed. A quantity, 'coupling specific acoustic impedance' is defined for the coupling between adjacent wells of the structu...In this paper,a new theory about sound absorption by pseudostochastic diffusors is proposed. A quantity, 'coupling specific acoustic impedance' is defined for the coupling between adjacent wells of the structure. The variation of particle velocity and sound pressure in the vicinity of the opening of wells is investigated and the exact solution of lst approach is derived. Moreover, the nonlinear effect is discussed. The rigorous formula to calculate the nonlinear coupling specific acoustic impedance is derived. Typical calculation shows the nonlinear effect can apparently improve the sound absorption character of the structure even if the sound pressure level of incident wave is medial.展开更多
The two-dimensional turbulent evaporating gas-droplet two-phase flows in an afterburner diffusor of turbo-fan jet engines are simulated by the k-ε turbulence model and the particle trajectory model. Comparison of pre...The two-dimensional turbulent evaporating gas-droplet two-phase flows in an afterburner diffusor of turbo-fan jet engines are simulated by the k-ε turbulence model and the particle trajectory model. Comparison of predicted gas velocity and temperature distributions with experimental results for the cases without liquid spray shows pretty good agreement. Gas-droplet two-phase flow predictions give plausible droplet trajectories, fuel-vapor concentration distribution, gas-phase velocity and temperature field in presence of liquid droplets. One run of computation with this method is made for a particular afterburner. The results indicate that the location of the atomizers is not favorable to flame stabilization and combustion efficiency. The proposed numerical modeling can also be adopted for optimization design and performance evaluation of afterburner combustors of turbo-fan jet engines.展开更多
文摘Based on theory proposed in the preceding paper [3]. the numerical calculation and eVerimental study of sound absorption by pseudostochastic diffusors are carried out in this paper. Average specific acoustic impedance of the whole structure is obtained. The nonlinear coupling specific resistance is emphatically analysed. The experiments of measuring normal absorption coefficient of the structure are made. The tested results agree with predicated data.
文摘In this paper,a new theory about sound absorption by pseudostochastic diffusors is proposed. A quantity, 'coupling specific acoustic impedance' is defined for the coupling between adjacent wells of the structure. The variation of particle velocity and sound pressure in the vicinity of the opening of wells is investigated and the exact solution of lst approach is derived. Moreover, the nonlinear effect is discussed. The rigorous formula to calculate the nonlinear coupling specific acoustic impedance is derived. Typical calculation shows the nonlinear effect can apparently improve the sound absorption character of the structure even if the sound pressure level of incident wave is medial.
文摘The two-dimensional turbulent evaporating gas-droplet two-phase flows in an afterburner diffusor of turbo-fan jet engines are simulated by the k-ε turbulence model and the particle trajectory model. Comparison of predicted gas velocity and temperature distributions with experimental results for the cases without liquid spray shows pretty good agreement. Gas-droplet two-phase flow predictions give plausible droplet trajectories, fuel-vapor concentration distribution, gas-phase velocity and temperature field in presence of liquid droplets. One run of computation with this method is made for a particular afterburner. The results indicate that the location of the atomizers is not favorable to flame stabilization and combustion efficiency. The proposed numerical modeling can also be adopted for optimization design and performance evaluation of afterburner combustors of turbo-fan jet engines.
