This paper provides a description of experimental studies of various dynamic distortion properties in a two-dimensional transonic diffuser. Based upon the measured dynamic pressure across the diffuser discharge section, the Δ PRMS, amplitude power density and probability density function have been analyzed. The results indicate that the dynamic distortion is closely related to the terminal shock wave stability of transonic diffuser, and the distribution of Δ PRMS and PSD are important Properties for dynamic distortion.
This paper provides a description of experimental studies of various dynamic distortion properties in a two-dimensional transonic diffuser. Based upon the measured dynamic pressure across the diffuser discharge section, the APRM«^ aplitude power density and probability density function have been analyzed. The results indicate that the dynamic distortion is closely related to the terminal shock wave stability of transonic diffuser, and the distribution of Δί'^^ and PSD are important properties for dynamic distortion. NomenclatureIntroduction b = Channel height This paper provides a description of experimental f = frequency studies of dynamic distortion properties in a two-L = diffuser length dimensional transonic diffuser. Dynamic distortion is Μ = Mach number one of the important subjects of inlet/engine compap = pressure tibility technique. It greatly affects the performance Ρ(Δρ) = probability density function and stability of the propulsion system. Recently t = time several specialists have shown their interest in investiTu = turbulence factor gating dynamic distortion mechanisms, prediction u = flow velocity methods of peak level of dynamic distortion and χ = streamwise coordinate (χ = 0 at difdynamic distortion simulation technology /1-4/. This fuser throat, positive streamwise) paper intends to provide a better understanding of y = vertical coordiante (y = 0 on the the dynamic distortion property and to support diffuser centerline, positive upward) development of flowfield prediction and simulation W = diffuser width for supersonic inlet. AR = area ratio of diffuser Dynamic distortion of inlet diffuser is increased APD = amplitude probability density funcwith the supercritical degree increase, so distortion is tion closely related to the transonic flow of diffuser. Most PSD = power spectral density function importantly, the formation of turbulence type of ΔΡ = fluctuating pressure dynamic distortion is produced by shock wave/ boundary layer interaction, combined with a subsonic, Subscripts adverse pressure gradient behind the terminal shock wave. 1 = inlet station For quantitative determination of dynamic distor-2 = exit station tion in a transonic diffuser, experiments of superc = cut-off filter critical transonic flow in a diffuser have been e = core flow performed. Generally, dynamic distortion has a ranav = average dom property. In the experimental investigation, the RMS = root-mean-square dynamic measuring technique was used. Dynamic
Three passive control methods of dynamic total pressure distortion have been developed in a 2–D diffuser in this paper: a fore–positioned shock stabilizing rod on a porous plate (model Q), a mid–positioned shock stabilizing rod on a porous plate (model Z), a porous plate (model K) and the original model without any control. From the experiment results, we observe that the PCSB (Passive Control of Shock wave / Boundary layer) technique used in the diffuser is effective to decrease the dynamic distortion. We conclude that: a) Different flow regions and their characteristic frequencies in the diffuser have been found. b) The interaction between the terminal shock wave and the boundary layer produces the peak value of the dynamic distortion. c) The steady total pressure varies inversely with the dynamic components of the total pressure along the height at the exit of the diffuser. d) The effects of different positions of the shock stabilizing rod on the dynamic distortion are relative to the upstream total pressure of the diffuser. e) New explanation about the production of the distortion has been given.
In this paper we provide information for the design of a 3D external compression inlet system which is affected by the exhaust plume of a missile. The inlet 3D flow field has been simulated by 3D time dependent Euler equations and solved using the J. D. Denton scheme. The total temperature and total pressure distributions are obtained for a quasi–steady state and the temperature increment (DT) and its variation rate (RDT) are calculated. Two definitions of DT and RDT are given and a simple condition has been put forward for calculating the inlet flow field with serious upstream distortion. Finally, an attenuation law is presented which estimates the temperature distortion in the inlet duct from the inlet entrance to the exit for different conditions and different intervals.
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