统一潮流控制器（unified power flow controller,UPFC）的概念最早是由美国Westing house公司的L.Gyugyi在1992年提出,是迄今为止功能最全面的FACTS（柔性交流输电系统）装置。UPFC由两个（或多个）共用直流部分的电压源换流器分别以...统一潮流控制器（unified power flow controller,UPFC）的概念最早是由美国Westing house公司的L.Gyugyi在1992年提出,是迄今为止功能最全面的FACTS（柔性交流输电系统）装置。UPFC由两个（或多个）共用直流部分的电压源换流器分别以并联和串联的方式接入输电系统,可以同时或选择性地控制输电线路的电压、阻抗、相位,实现线路有功、无功潮流控制,并可提供独立可控并联无功补偿。UPFC具有灵活控制系统潮流、提高电网传输能力及改善系统稳定性等多种功能。展开更多
The large-eddy simulation(LES)with the dynamic Smagorinsky model is used to predict the interior sound of an idealized vehicle cabin under the excitation of the wall pressures from turbulent channel flows.In compariso...The large-eddy simulation(LES)with the dynamic Smagorinsky model is used to predict the interior sound of an idealized vehicle cabin under the excitation of the wall pressures from turbulent channel flows.In comparison with direct numerical simulation(DNS),the LES results overpredict the sound pressure level(SPL)at low frequencies and underpredict the SPL at high frequencies.The incorrect predictions result from the incorrect prediction of LES on surface pressures,where the LES over-estimates the wavenumber and frequencies spectra of surface pressures at small wavenumbers and frequencies and under-estimates the spectra at large wavenumbers and frequencies.However,the LES results are close to the filtered-DNS results,implying that the unresolved scales are also important to surface pressures and interior sound.The Euler-Bernoulli beam under the excitation of exterior pressures,which serves as a simple model for aero-vibro-acoustics in the case of hydrodynamical fast,is used to explain the observed predictions and show that the Corcos model cannot represent the variation of turbulence pressure spectra at wavenumbers and frequencies.Therefore,the new requirement for the LES method,when applied to fluid-structural-acoustic interaction problems at high Reynolds numbers,is the correct prediction of wavenumber and frequency spectra of turbulence wall pressure.展开更多
文摘统一潮流控制器（unified power flow controller,UPFC）的概念最早是由美国Westing house公司的L.Gyugyi在1992年提出,是迄今为止功能最全面的FACTS（柔性交流输电系统）装置。UPFC由两个（或多个）共用直流部分的电压源换流器分别以并联和串联的方式接入输电系统,可以同时或选择性地控制输电线路的电压、阻抗、相位,实现线路有功、无功潮流控制,并可提供独立可控并联无功补偿。UPFC具有灵活控制系统潮流、提高电网传输能力及改善系统稳定性等多种功能。
基金Basic Science Center Program of the National Natural Science Foundation of China for“Multi-scale Problems in Nonlinear Mechanics”(Grant No.11988102)National Key Project(Grant No.GJXM92579).
文摘The large-eddy simulation(LES)with the dynamic Smagorinsky model is used to predict the interior sound of an idealized vehicle cabin under the excitation of the wall pressures from turbulent channel flows.In comparison with direct numerical simulation(DNS),the LES results overpredict the sound pressure level(SPL)at low frequencies and underpredict the SPL at high frequencies.The incorrect predictions result from the incorrect prediction of LES on surface pressures,where the LES over-estimates the wavenumber and frequencies spectra of surface pressures at small wavenumbers and frequencies and under-estimates the spectra at large wavenumbers and frequencies.However,the LES results are close to the filtered-DNS results,implying that the unresolved scales are also important to surface pressures and interior sound.The Euler-Bernoulli beam under the excitation of exterior pressures,which serves as a simple model for aero-vibro-acoustics in the case of hydrodynamical fast,is used to explain the observed predictions and show that the Corcos model cannot represent the variation of turbulence pressure spectra at wavenumbers and frequencies.Therefore,the new requirement for the LES method,when applied to fluid-structural-acoustic interaction problems at high Reynolds numbers,is the correct prediction of wavenumber and frequency spectra of turbulence wall pressure.
