The suppressing design of the engine nacelle in an aircraft can benefit from the development of the prediction system for the sound fields in engine ducts which includes the prediction of the source generation and tha...The suppressing design of the engine nacelle in an aircraft can benefit from the development of the prediction system for the sound fields in engine ducts which includes the prediction of the source generation and that of sound propagation in ducts. First, the acoustic match mode principle between the source modes of rotor stator interaction noise and the propagation modes is presented in this paper. Second, by utilizing this principle, the theoretical prediction method for rotor stator interaction noise generation and its propagation and attenuation in an annular duct with multi treatments is developed. That means that the prediction of sound propagation and attenuation in the segmented ducts might no longer completely depend on the in duct mode measurements, and the investigation on the sound propagation and attenuation in ducts can be accomplished not only by acoustic mode measurement, but also by making use of the source prediction to determine the source modes excited by rotor stator interaction. The effects of fan speed, blade/vane numbers, axial spacing between rotor and stator on the in duct sound attenuation and generated sound power level before and after ducts (also including the sound power level of blade passing frequency and its harmonics at the inlet of ducts) have been numerically calculated by using this prediction method. The reliability of this prediction method is verified by reasonable agreement between the predicted results with measured results in references. By analyzing the results of calculating cases, some reference criteria are provided for the engineering design of the suppressing engine nacelle.展开更多
In this study, an advanced Lagrangian vortex- boundary element method is applied to simulate the unsteady impeller-diffuser interactions in a diffuser pump not only for design but also for off-design considerations. I...In this study, an advanced Lagrangian vortex- boundary element method is applied to simulate the unsteady impeller-diffuser interactions in a diffuser pump not only for design but also for off-design considerations. In velocity calculations based on the Biot-Savart law we do not have to grid large portions of the flow field and the calculation points are concentrated in the regions where vorticity is present. Lagrangian representation of the evolving vorticity field is well suited to moving boundaries. An integral pressure equation shows that the pressure distribution can be estimated directly from the instantaneous velocity and vorticity field. The numerical results are compared with the experimental data and the comparisons show that the method used in this study can provide us insight into the complicated unsteady impeller-diffuser interaction phenomena in a diffuser pump.展开更多
为探究叶片出口梯形切割对离心泵蜗壳流激噪声的影响,以一台比转速为66的单级单吸离心泵为对象,通过定义切割宽度系数δ与径向高度系数γ,设计了9种切割方案。基于RNG k-ε湍流模型对离心泵进行全三维非定常数值模拟,在此基础上采用边...为探究叶片出口梯形切割对离心泵蜗壳流激噪声的影响,以一台比转速为66的单级单吸离心泵为对象,通过定义切割宽度系数δ与径向高度系数γ,设计了9种切割方案。基于RNG k-ε湍流模型对离心泵进行全三维非定常数值模拟,在此基础上采用边界元法(boundary element method,BEM)计算内场噪声,采用结构有限元法(finite element method,FEM)耦合声学边界元方法计算外场流激噪声;分析不同切割方案下离心泵水力特性和噪声幅射特性,经试验方法验证数值计算的准确性。研究表明:动静干涉是离心泵蜗壳流激噪声产生的主要原因,合理的叶片出口梯形切割能使离心泵水力性能基本稳定的同时有效降低动静干涉强度及蜗壳流激噪声水平;声学性能最优切割方案,叶频处的进、出口监测点声压级分别下降13%和7.5%,外场噪声监测点声压级下降2.4%。展开更多
This paper deals with the experimental quantification of the unsteady effects of the interactions between rotor and stator rows in high speed compressors. Due to the fact that the levels of the periodic fluctuations a...This paper deals with the experimental quantification of the unsteady effects of the interactions between rotor and stator rows in high speed compressors. Due to the fact that the levels of the periodic fluctuations arising from the unsteady interaction may be low compared with the random fluctuations arising from the measurement uncertainties, it is crucial to minimize the errors inherent to the used technique. The first part of the paper concentrates on technical details relative to the experimental process. The second part is devoted to the data post-processing. Two tools for analysing the rotor-stator interactions are presented. The first tool is based on a decomposition of the flow field which was initially introduced to solve numerical problems when attempting to calculate the flow field in a multi-row configuration. The second tool is based on a spectral analysis of the signal, that qualifies the interaction in a sense of circumferential spinning lobes. Experimental results obtained within both an axial and a centrifugal high speed compressors are used to illustrate the data processing. In both cases, the effects of the unsteady interaction are quantified.展开更多
An analysis of the experimental results obtained by laser two focus anemometry in the rotor-stator inter-row region of a high-speed high-pressure centrifugal compressor is presented with the aim of quantifying the uns...An analysis of the experimental results obtained by laser two focus anemometry in the rotor-stator inter-row region of a high-speed high-pressure centrifugal compressor is presented with the aim of quantifying the unsteady effects of the rotor-stator interaction. Two complementary methods are used. First, the results are analyzed in terms of the time-averaging procedure developed by Adamczyk. The purely time dependent correlations of the velocity components are quantified. They show that the unsteady interaction is mainly due to the splitter wake-vane interaction. Then, it is shown that the rotor-stator interaction produces spatial harmonics which are identified as spinning modes by means of Fourier series.展开更多
A numerical method is developed for the simulation of rotor\|stator interactions in a compessor or turbine stage. This method solves quasi\|three\|dimensional Navier\|Stokes equations by an implicit high\|resolution f...A numerical method is developed for the simulation of rotor\|stator interactions in a compessor or turbine stage. This method solves quasi\|three\|dimensional Navier\|Stokes equations by an implicit high\|resolution finite volume approach.A fully conservative method is designed to compute the inviscid and viscous fluxes at the interface of rotor and stator grids. Numerical results of rotor\|stator interactions in a transonic compressor stage are presented. The mechanism of rotor\|stator interactions in this compressor stage is discussed in terms of the computational results.展开更多
A modal analysis method of the rotor-stator interactions in multistage compressors has been developed by LMFA.This method,based on a double modal decomposition of the flow over space and time,has been applied to nu-me...A modal analysis method of the rotor-stator interactions in multistage compressors has been developed by LMFA.This method,based on a double modal decomposition of the flow over space and time,has been applied to nu-merical and experimental results of the high-speed 3?-stage compressor CREATE based at LMFA,Lyon-France.It reveals the presence of a very strong rotor-stator interaction which completely drives the flow at casing behind all the rotors.This modal analysis method applied to an unsteady RANS simulation permits to calculate the en-ergy of the rotor-stator interactions and to plot energetic meridian maps to explain experimental results and to analyze the interaction in the whole machine.展开更多
文摘The suppressing design of the engine nacelle in an aircraft can benefit from the development of the prediction system for the sound fields in engine ducts which includes the prediction of the source generation and that of sound propagation in ducts. First, the acoustic match mode principle between the source modes of rotor stator interaction noise and the propagation modes is presented in this paper. Second, by utilizing this principle, the theoretical prediction method for rotor stator interaction noise generation and its propagation and attenuation in an annular duct with multi treatments is developed. That means that the prediction of sound propagation and attenuation in the segmented ducts might no longer completely depend on the in duct mode measurements, and the investigation on the sound propagation and attenuation in ducts can be accomplished not only by acoustic mode measurement, but also by making use of the source prediction to determine the source modes excited by rotor stator interaction. The effects of fan speed, blade/vane numbers, axial spacing between rotor and stator on the in duct sound attenuation and generated sound power level before and after ducts (also including the sound power level of blade passing frequency and its harmonics at the inlet of ducts) have been numerically calculated by using this prediction method. The reliability of this prediction method is verified by reasonable agreement between the predicted results with measured results in references. By analyzing the results of calculating cases, some reference criteria are provided for the engineering design of the suppressing engine nacelle.
文摘In this study, an advanced Lagrangian vortex- boundary element method is applied to simulate the unsteady impeller-diffuser interactions in a diffuser pump not only for design but also for off-design considerations. In velocity calculations based on the Biot-Savart law we do not have to grid large portions of the flow field and the calculation points are concentrated in the regions where vorticity is present. Lagrangian representation of the evolving vorticity field is well suited to moving boundaries. An integral pressure equation shows that the pressure distribution can be estimated directly from the instantaneous velocity and vorticity field. The numerical results are compared with the experimental data and the comparisons show that the method used in this study can provide us insight into the complicated unsteady impeller-diffuser interaction phenomena in a diffuser pump.
文摘为探究叶片出口梯形切割对离心泵蜗壳流激噪声的影响,以一台比转速为66的单级单吸离心泵为对象,通过定义切割宽度系数δ与径向高度系数γ,设计了9种切割方案。基于RNG k-ε湍流模型对离心泵进行全三维非定常数值模拟,在此基础上采用边界元法(boundary element method,BEM)计算内场噪声,采用结构有限元法(finite element method,FEM)耦合声学边界元方法计算外场流激噪声;分析不同切割方案下离心泵水力特性和噪声幅射特性,经试验方法验证数值计算的准确性。研究表明:动静干涉是离心泵蜗壳流激噪声产生的主要原因,合理的叶片出口梯形切割能使离心泵水力性能基本稳定的同时有效降低动静干涉强度及蜗壳流激噪声水平;声学性能最优切割方案,叶频处的进、出口监测点声压级分别下降13%和7.5%,外场噪声监测点声压级下降2.4%。
文摘This paper deals with the experimental quantification of the unsteady effects of the interactions between rotor and stator rows in high speed compressors. Due to the fact that the levels of the periodic fluctuations arising from the unsteady interaction may be low compared with the random fluctuations arising from the measurement uncertainties, it is crucial to minimize the errors inherent to the used technique. The first part of the paper concentrates on technical details relative to the experimental process. The second part is devoted to the data post-processing. Two tools for analysing the rotor-stator interactions are presented. The first tool is based on a decomposition of the flow field which was initially introduced to solve numerical problems when attempting to calculate the flow field in a multi-row configuration. The second tool is based on a spectral analysis of the signal, that qualifies the interaction in a sense of circumferential spinning lobes. Experimental results obtained within both an axial and a centrifugal high speed compressors are used to illustrate the data processing. In both cases, the effects of the unsteady interaction are quantified.
文摘An analysis of the experimental results obtained by laser two focus anemometry in the rotor-stator inter-row region of a high-speed high-pressure centrifugal compressor is presented with the aim of quantifying the unsteady effects of the rotor-stator interaction. Two complementary methods are used. First, the results are analyzed in terms of the time-averaging procedure developed by Adamczyk. The purely time dependent correlations of the velocity components are quantified. They show that the unsteady interaction is mainly due to the splitter wake-vane interaction. Then, it is shown that the rotor-stator interaction produces spatial harmonics which are identified as spinning modes by means of Fourier series.
文摘A numerical method is developed for the simulation of rotor\|stator interactions in a compessor or turbine stage. This method solves quasi\|three\|dimensional Navier\|Stokes equations by an implicit high\|resolution finite volume approach.A fully conservative method is designed to compute the inviscid and viscous fluxes at the interface of rotor and stator grids. Numerical results of rotor\|stator interactions in a transonic compressor stage are presented. The mechanism of rotor\|stator interactions in this compressor stage is discussed in terms of the computational results.
基金the CNRS and the company Snecma (SAFRAN) which support the compressor CREATE research program
文摘A modal analysis method of the rotor-stator interactions in multistage compressors has been developed by LMFA.This method,based on a double modal decomposition of the flow over space and time,has been applied to nu-merical and experimental results of the high-speed 3?-stage compressor CREATE based at LMFA,Lyon-France.It reveals the presence of a very strong rotor-stator interaction which completely drives the flow at casing behind all the rotors.This modal analysis method applied to an unsteady RANS simulation permits to calculate the en-ergy of the rotor-stator interactions and to plot energetic meridian maps to explain experimental results and to analyze the interaction in the whole machine.
基金National Natural Science Foundation of China (51176013)Ph.D. Programs Foundation of Ministry of Education of China (20091101110014)National High-tech Research and Development Program of China (2007AA050502)