摘要
为对倾斜管道内的流动不稳定特性进行研究,建立了适用于不同工况条件的数学模型和本构关系。以频域法为基础,对守恒方程进行小扰动线性化和拉氏变换可得到用于描述流体流动稳定性的传递函数。使用尼奎斯特稳定性判据,绘制不同工况参数下的尼奎斯特图来判断流动的稳定性。对线性化模型的可靠性进行验证,在可靠性验证的基础上,对各种工况参数下的流动不稳定性进行研究,得到不同工况下的流动不稳定边界图。验证结果表明:模型的计算结果与实验数据的误差在10%以内。增大质量流速使流体的进口和出口密度差减小,有利于流动的稳定;相反,增大对流体施加的热流密度,使流体的进口和出口密度差增大,不利于流动的稳定,因此临界热流密度随质量流速的增大而增大;增大入口节流系数,可以抑制入口处流量的脉动,有利于流动的稳定,但是临界入口节流系数随质量流速的增大而减小;此外,增大入口过冷度在所研究的参数范围内有利于流动的稳定,得到的热流密度和入口过冷度不稳定边界线是单调的。
In order to study the flow instability characteristics in inclined pipe,mathematical models and constitutive relations suitable for different working conditions are established.Based on the frequency domain method,the transfer function used to describe the stability of fluid flow can be obtained by performing small perturbation linearization and Laplace transform on the conservation equation.Using the Nyquist stability criterion,Nyquist diagrams are drawn under different working conditions to judge the stability of the flow.The reliability of the linearized model is verified.On the basis of reliability verification,the flow instability under various working conditions is studied,and the boundary diagrams of flow instability under different working conditions are obtained.The verification results show that the error between the calculated results of the model and the experimental data is within 10%.The research results show that increasing the mass flow rate reduces the density difference between the inlet and the outlet of the fluid,which is beneficial to the stability of the flow.On the contrary,increasing the heat flux applied to the fluid increases the density difference between the inlet and the outlet of the fluid,which is not conducive to the stability of the flow.Therefore,the critical heat flux increases as the mass flow rate increases.Increasing the inlet throttling coefficient can suppress the pulsation of the flow at the inlet,which is conducive to the stability of the flow.However,the critical inlet throttling coefficient decreases as the mass flow rate increases.In addition,increasing the inlet subcooling degree is beneficial to the stability of the flow within the studied parameter range,and the obtained heat flux and inlet subcooling instability boundary line are monotonic.
作者
辛亚飞
聂超
毕凌峰
卿浩
杨浩昱
杨冬
Xin Yafei;Nie Chao;Bi Lingfeng;Qing Hao;Yang Haoyu;Yang Dong(State key laboratory of multiphase flow in power engineering,Xiwi Jiaotong University,Xian 710049,China)
出处
《电力科技与环保》
2022年第3期195-201,共7页
Electric Power Technology and Environmental Protection
基金
国家自然科学基金项目(52076172)。
关键词
倾斜管道
流动不稳定性
频域法
传递函数
尼奎斯特图
inclined pipe
flow instability
frequency domain method
transfer function
Nyquist diagram
