Research And Application Of Composite Probe In Gas Velocity Measurement

Gas velocity measurement plays an important role in various fields such as chemical industry,aerospace and so on.In the experiments of universities and research institutes,air velocity is also an important parameter that needs to be paid attention to and studied.Therefore,the accurate measurement of airflow velocity is of great significance.At present,both the five-hole probe technology and the total temperature probe technology have been developed to some extent,but the composite probe formed by combining the two has not been deeply studied,and the research on the five-hole probe is mainly focused on the subsonic ideal gas range.Therefore,in order to measure the flow field more accurately and conveniently,this paper uses a composite probe combined with a five-hole probe and a total temperature probe to complete the following work through experimental measurement and three-dimensional numerical simulation:(1)Set up a checking and testing platform to realize real-time collection and storage of experimental data;The displacement control system of the subsonic ideal gas wind tunnel test platform is built.The experimental platform of supersonic ideal gas Laval ejector was built.An experimental platform for measuring real gas R134 a was built.(2)The structure and form of the composite probe were designed.The shape of the five-hole probe with different cone angles is simulated.For transonic fluid,the cone Angle of60° is more suitable for flow field measurement.The structure of the total temperature probe was studied,and the measurement effect of the total temperature probe was simulated.The thermal insulation ability of the stagnation cover was measured experimentally,and the total temperature recovery coefficient and directional insensitivity of the total temperature probe under different Ma were measured experimentally.(3)The subsonic and supersonic ideal gases were simulated and experimentally investigated with the composite probe.The pressure,temperature and Ma in the simulation results are analyzed.The subsonic and supersonic five-hole probes were calibrated and checked.Three calibration coefficient diagrams of direction,total pressure and static pressure were drawn.The velocity of subsonic and supersonic flow is calculated by three-dimensional interpolation method,and the error is less than 4% compared with the standard value of the experimental platform.(4)The simulation and experimental study of real gas R134 a are carried out.The composite probe was used to simulate the real gas flow under different m A.Because the physical parameters of real gas are different from those of ideal gas,the relation between isentropic and shock wave of real gas is deduced.The real gas flow in R134 A closed pipeline was measured by the design of a tapering nozzle,and the accuracy of the experimental results was verified.The error was less than 3%.