水力机械非定常流动内能变化与水力损失机理研究

This project proposes to build a mathematical model and numerical analysis method to study the hydraulic loss and energy dissipation, and investigate the unsteady characteristic of hydraulic loss, temperature field and energy dissipation in pulsatile vortex flow. In this research, the hydraulic loss and the intensity of local vortex flow are evaluated from the view of internal energy change, which will also illustrate the loss mechanism in centrifugal pumps under different working conditions. This project will carry out mathematical models with theoretical analysis, numerical simulation and model test in order to present energy conversion and dissipation by combining with thermodynamic concepts like entropy and enthalpy. The study will concentrate on quantitative analysis and mathematical model on energy conversion and distribution of the viscous fluid in the centrifugal pump, criterion research on the intensity of local vortex flow and energy dissipation analysis, relationship between energy dissipation and hydraulic loss, and simulation and test on unsteady temperature and pressure field. With a perspective of internal energy change, this project will promote the application of thermodynamic method in theoretical analysis and model test on hydraulic machines. A new method on the mechanism of energy transmission in hydraulic machines will be investigated, which will open up new vistas of the analysis on conservation of momentum and energy in hydraulic machines, especially in centrifugal pumps. This method could also improve the optimization design of hydraulic machines.

本研究将试图建立水力机械水力损失与能量耗散之间的数学模型和数值分析方法，研究离心泵内部漩涡脉动流的水力损失、温度场和能量耗散的非定常特性，从水流内能变化角度评估水力损失和涡漩强度，并从内能变化上揭示离心泵不同运行工况下的水力损失机理。采用数理模型、数值模拟和模型试验相结合的分析方法，引入熵产、焓变等概念，分析离心泵内部流体介质能量转换与耗散过程，详细研究介质能量分布与转换定量表征的数学模型、局部涡漩结构强度、能量耗散与水力损失映射关系、温度场压力场非定常特性测量和计算分析。本研究从内能变化角度分析水力损失的机理，促进热力学研究方法在水力机械理论分析和试验方法中的应用，形成水力机械能量传输机理新的研究方法，可为水力机械尤其离心泵动量和能量守恒分析计算拓展新的途径，促进水力机械优化设计方法的进步。

离心泵经常在非设计工况下运行，内部存在的复杂流动现象会引起水力损失和压力脉动；某些工况可能出现强烈的涡旋流动，影响泵的高效稳定运行。定量研究造成离心泵损失的流动结构和其能量特性，可以更精准地预测优化设计的效果，具有重要的工程应用意义。本研究在离心泵流动研究中引入热力学方法的分析体系，通过研究流体能量分布与转换的定量表征，提出了适用于离心泵内部流动的热力学能、熵变量和能量耗散研究方法，用以评估损失并定量比较涡旋等流动现象的能量耗散特性。通过建立离心泵局部流动结构能量耗散的定量表征，重点针对不同进口流量条件下离心泵单相流动叶轮分离涡旋、旋转失速、动静干涉、进口回流涡旋和隔舌冲击脱流等流动现象，定量比较了这些流动现象的能量耗散和压力脉动特性，探讨了非定常涡旋等流动结构对离心泵各个过流部件水力损失的影响。