Numerical Simulation And Experimental Validation Of Differential Pressure Throttle Devices

Multi-hole orifice and wedge throttle devices are two different types of throttling differential pressure flow measurement instruments,which have significant advantages over traditional differential pressure throttling devices and have a wide range of application prospects in fluid measurement.The outstanding advantages of the Multi-hole orifice throttle devices are that balancing the flow field,achieving a bidirectional measurement,small flow noise and small permanent pressure loss.The Wedge throttle devices can measure a variety of fluid media and still maintain high measurement accuracy even with high viscosity and low Reynolds number,and for some of the harsh conditions of the flow measurement,such as low flow rate,small flow,large diameter,which has a huge advantage and function.Take into account these throttling characteristics,domestic and foreign countries have conducted related research.In this thesis,taking these two types of throttling devices as the research object,and combining the theoretical analysis,computational fluid dynamics numerical simulation with real-flow experimental calibration method to explore the effect of Reynolds number,fluid medium and structural parameters on the performance of multi-hole orifice and wedge throttle devices.Especially for the influence of flow field characteristics,discharge coefficient and permanent pressure loss,and through the research results to provide reference for the optimization of its structural design.The main research work of this article is as follows:(1)According to the basic working principle of the differential pressure flowmeter,the expression of the volume flow of an incompressible fluid containing the discharge coefficient is calculated by combining the Bernoulli equation,the continuity equation and the flow equation.According to the structural characteristics of the multi-hole orifice and wedge throttle devices,the expression of the discharge coefficients of the two kinds of throttling devices is transformed.It offers a theoretical basis for numerical simulation and real flow experiments.(2)Simulation software ANSYS-CFX is used for numerical simulation of the working process of two types of throttling devices,providing for the establishment of three-dimensional geometric model,mesh division,boundary condition setting,and solution calculation.The influence of different Reynolds number and fluid medium on the discharge coefficient of the multi-hole orifice and wedge throttle devices is studied.The flow field characteristics of the multi-hole orifice and the wedge throttle devices are analyzed,respectively.(3)Based on the numerical simulation results,the influence of structural parameters on the performance of the multi-hole orifice and wedge throttle devices is investigated.The effect of the three different structures,equivalent diameter ratios,pipe diameters,the number of function holes,the size of the hole in the center hole,the circumference distribution of the balance hole,the thickness of the orifice plate on the discharge coefficient and permanent pressure of the multi-hole orifice throttle devices are mainly studied.Build on the results of the study,the structure of the multi-hole orifice is analyzed,and the optimal structure is proposed to provide reference for the design optimization of the structure of the multi-hole orifice.For the wedge throttle devices,the influence of the wedge ratio and pipe diameter on the discharge coefficient of the wedge throttle devices is mainly studied,and the influence on the flow field of the wedge throttle devices is analyzed through the velocity streamline diagram.(4)According to the structural parameters of the numerical simulation,several groups are selected for real-flow experiments in calibration.Flow calibration experimental results data are collated,and the discharge coefficient achieved from real flow experiments is compared with the results of numerical simulation.The discharge coefficient of the two results is basically consistent,which verified the rationality and accuracy of the numerical simulation results.