Method for measuring average Mach number of nozzle outlet

Abstract

The invention provides a method for measuring the average Mach number of a nozzle outlet. The method is used to indirectly measure the average Mach number Ma of the nozzle outlet based on measured pressure, temperature and mass flow, and obtain the average Mach number Ma of the nozzle outlet by measuring the total temperature T0 * of airflow of a nozzle inlet, static pressure P1 of airflow of thenozzle outlet and the mass flow m of airflow flowing through the nozzle. A measuring instrument does not need to be inserted into a high-speed flow field of the nozzle outlet, and disturbance to the flow field is reduced. Compared with a method for obtaining the average Mach number Ma of the nozzle outlet through a laser Doppler velocimeter LDV and a particle image velocimeter PIV, the method onlyneeds to arrange an inlet total temperature measuring point at the nozzle inlet, arrange a static pressure measuring point at the nozzle outlet and measure the flow passing through the nozzle; the measurement cost is relatively low, and solid particles do not need to be added into the flow field. The maximum deviation between the nozzle outlet average Mach number Ma calculated according to the method and the CFD numerical calculation result does not exceed 6.2%.

Description

technical field [0001] The invention relates to the application field of an aero-engine pre-swirl gas supply system, in particular to a method for measuring the average Mach number at the outlet of a pre-swirl nozzle. Background technique [0002] The pre-swirl nozzle is an important part of the aero-engine pre-swirl air supply system. Its function is to accelerate the airflow to form a larger circumferential component, reduce the static temperature of the airflow and the relative speed between the airflow and the turntable, so as to achieve the purpose of reducing the relative total temperature of the airflow. . For any pre-swirl system, if the peripheral velocity generated by the pre-swirl nozzle is large enough, the relative total temperature at the outlet of the system will even be lower than the absolute total temperature at the inlet, and the temperature drop of the pre-swirl system can be realized. [0003] For an adiabatic pre-swirling system and the pre-swirling ch...

AI Technical Summary

Problems solved by technology

Except for the LDV and PIV measurement methods, these four measurement methods are all contact measurement methods, which need to insert measuring points into the high-speed flow field at the nozzle outlet. If too many measuring points are arranged, the flow field at the nozzle outlet will be seriously disturbed. , resulting in distortion of the measurement results, but if too few measuring points are arranged, it will affect the reliability of the measurement results

However, the LDV and PIV methods have higher requirements on the measurement object, need to be able to directly capture the flow field, and often need to add particles to the measurement object, which are rarely used when measuring the nozzle outlet flow velocity

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