摘要
混流泵在降速过程中的内部流动特性变化对其性能和稳定性有重要影响。针对这一问题,该研究探究了混流泵在降速过程中内部流动的复杂性,尤其关注不同降速方式对泵内压力脉动特性的影响。通过构建多通道测试系统,收集了混流泵在不同降速方式下的外特性参数信号和泵内压力脉动信号。并采用非稳态信号处理技术,从时域、频域和时频三方面探究不同降速方式对叶轮出口和导叶内部的压力脉动特性的影响以及二者之间的相关性。结果表明,泵内压力脉动的峰值和样本熵的变化趋势与不同降速方式的幂指数呈正相关关系;在整个降速过程中叶轮出口压力脉动对导叶内压力脉动起主导作用;叶轮出口和导叶内部压力脉动之间的相干频率主要集中于80~120 Hz之间;在不同降速过程中叶轮出口和导叶内部的压力脉动之间强相关区域的频带范围保持不变,但是强相关区域在整个降速过程频带范围中的占比有所变化;对于具有固定初始转速和目标转速的降速过程,降速方式的改变不会影响叶轮出口和导叶内压力脉动的相干频率。研究结论可为揭示混流泵瞬态运行特性及提高混流泵降速运行中的稳定性提供参考。
Internal flow has a significant impact on the performance and stability of a mixed-flow pump during deceleration.This article aims to explore the complex internal flow in mixed-flow pumps during deceleration.A multi-channel testing system was constructed to clarify the impact of different decelerations on the pressure pulsation inside the pump.External characteristic parameters and internal pressure pulsation of mixed-flow pumps were collected under different deceleration modes.Non-stationary signal processing was introduced to determine the effects of speed reduction on the pressure pulsation at the impeller outlet and inside the guide vanes.Three domains were divided into time,frequency,and time-frequency,as well as the correlation between them.The results show that the decline gradient of head and flow under different deceleration modes was positively correlated with the decline speed.The energy entropy ratio of the pressure pulsation in the pump showed a downward trend during deceleration.It indicated that the pressure pulsation was gradually stabilized with the decrease of the speed in the pump.The peak value of pressure pulsation and the changing trend of sample entropy were positively correlated with the exponential of the deceleration modes.The changing trend of impeller outlet pressure pulsation was consistent with the speed transformation during the whole deceleration.The forward transfer entropy under different deceleration modes was greater than the reverse transfer entropy.Therefore,the pressure pulsation at the outlet of the impeller was dominated that in the guide vane.The high energy region of the pressure pulsation was mainly concentrated in the blade passing frequency 4fn and the high-order harmonic 8fn,whereas,the amplitude was positively correlated with the index of the speed transformation.The strong correlation region was concentrated in the two frequency bands of rotation frequency fn and blade passing frequency 4fn in the process of deceleration.The high amplitude region of pressure pulsation at the outlet of the impeller was concentrated in the blade passing frequency of 4fn,while the frequency of the pressure fluctuation component with the highest amplitude inside the guide vane was 3fn.The partial coherence frequency between the pressure pulsation at the impeller outlet and inside the guide vane was in the range of 80 and 120 Hz.There was no change in the frequency range of the strong correlation region between the pressure pulsations at the impeller outlet and inside the guide vane during different decelerations.But there was a variation in the proportion of the strong correlation region in the frequency range of the entire deceleration.In the deceleration with the fixed initial speed and target speed,the deceleration mode shared no effect on the coherent frequency of pressure fluctuation in the impeller outlet and guide vane.The finding can provide a strong reference to reveal the transient operation for the high stability of mixed-flow pump in down-speed operation.
作者
卢金玲
王阳
代俊航
朱国俊
宣奕帆
王李科
LU Jinling;WANG Yang;DAI Junhang;ZHU Guojun;XUAN Yifan;WANG Like(State Key Laboratory of Eco-hydraulics in Northwest Arid Region,Xi’an University of Technology,Xi’an 710048,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2024年第12期86-95,共10页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金项目(51909212,52309118)。
关键词
混流泵
信号处理
相关性分析
传递熵
压力脉动
mixed-flow pump
signal processing
correlation analysis
transfer entropy
pressure pulsation
