Inevitable geometric variations significantly affect the performance of turbines or even that of entire engines;thus,it is necessary to determine their actual characteristics and accurately estimate their impact on pe...Inevitable geometric variations significantly affect the performance of turbines or even that of entire engines;thus,it is necessary to determine their actual characteristics and accurately estimate their impact on performance.In this study,based on 1781 measured profiles of a typical turbine blade,the statistical characteristics of the geometric variations and the uncertainty impact are analyzed,and some commonly used uncertainty modelling methods based on Principal-Component Analysis(PCA)are verified.The geometric variations are found to be evident,asymmetric,and non-uniform,and the non-normality of the random distributions is non-negligible.The performance is notably affected,which is manifested as an overall offset,a notable scattering,and significant deterioration in several extreme cases.Additionally,it is demonstrated that the PCA reconstruction model is effective in characterizing major uncertainty characteristics of the geometric variations and their impact on the performance with almost the first 10 PCA modes.Based on a reasonable profile error and mean geometric deviation,the Gaussian assumption and stochasticprocess-based model are also found to be effective in predicting the mean values and standard deviations of the performance variations.However,they fail to predict the probability of some extreme cases with high loss.Finally,a Chi-square-based correction model is proposed to compensate for this deficiency.The present work can provide a useful reference for uncertainty analysis of the impact of geometric variations,and the corresponding uncertainty design of turbine blades.展开更多
A vibration feeder is a piece of equipment for rationing and conveying powder,particle and block materials.In order to test the regeneration performance of de-dusting medium for high-temperature coal gas,a set of de-d...A vibration feeder is a piece of equipment for rationing and conveying powder,particle and block materials.In order to test the regeneration performance of de-dusting medium for high-temperature coal gas,a set of de-dusting medium-feeding systems was designed quantitatively.The de-dusting medium-feeding system is used in the gasification process for cleaning coal gas.The system is mainly composed of a hopper unit,control unit and feeding unit.In order to optimize the feeding stability of the coal-gas dust-removal medium vibration feeding system,the setting and scope of the following design factors and operating factors are investigated.Specifically,it includes the influence of gate-valve-opening adjustment of the control unit on the feeding stability of a vibrating feeding system;the influence of the gap size of the dipleg of the control unit on the feeding sensitivity of the vibration system;the influence of the particle size of the de-dusting medium on the operating range of the vibrating feeding system;the influence of the digitization of the working-current indicator of electromagnetic vibrating feeders on measurement variation and the process variation of a vibration feeding system.This vibration feeding system can realize the function of precise and quantitative feeding of the de-dusting medium,which can meet the design requirements of subsequent experimental research.展开更多
基金supported by the National Science and Technology Major Project, China (No. J2019-II-0012-0032)
文摘Inevitable geometric variations significantly affect the performance of turbines or even that of entire engines;thus,it is necessary to determine their actual characteristics and accurately estimate their impact on performance.In this study,based on 1781 measured profiles of a typical turbine blade,the statistical characteristics of the geometric variations and the uncertainty impact are analyzed,and some commonly used uncertainty modelling methods based on Principal-Component Analysis(PCA)are verified.The geometric variations are found to be evident,asymmetric,and non-uniform,and the non-normality of the random distributions is non-negligible.The performance is notably affected,which is manifested as an overall offset,a notable scattering,and significant deterioration in several extreme cases.Additionally,it is demonstrated that the PCA reconstruction model is effective in characterizing major uncertainty characteristics of the geometric variations and their impact on the performance with almost the first 10 PCA modes.Based on a reasonable profile error and mean geometric deviation,the Gaussian assumption and stochasticprocess-based model are also found to be effective in predicting the mean values and standard deviations of the performance variations.However,they fail to predict the probability of some extreme cases with high loss.Finally,a Chi-square-based correction model is proposed to compensate for this deficiency.The present work can provide a useful reference for uncertainty analysis of the impact of geometric variations,and the corresponding uncertainty design of turbine blades.
文摘A vibration feeder is a piece of equipment for rationing and conveying powder,particle and block materials.In order to test the regeneration performance of de-dusting medium for high-temperature coal gas,a set of de-dusting medium-feeding systems was designed quantitatively.The de-dusting medium-feeding system is used in the gasification process for cleaning coal gas.The system is mainly composed of a hopper unit,control unit and feeding unit.In order to optimize the feeding stability of the coal-gas dust-removal medium vibration feeding system,the setting and scope of the following design factors and operating factors are investigated.Specifically,it includes the influence of gate-valve-opening adjustment of the control unit on the feeding stability of a vibrating feeding system;the influence of the gap size of the dipleg of the control unit on the feeding sensitivity of the vibration system;the influence of the particle size of the de-dusting medium on the operating range of the vibrating feeding system;the influence of the digitization of the working-current indicator of electromagnetic vibrating feeders on measurement variation and the process variation of a vibration feeding system.This vibration feeding system can realize the function of precise and quantitative feeding of the de-dusting medium,which can meet the design requirements of subsequent experimental research.
