A Measuring Method of Average Mach Number at Nozzle Outlet
A technology of nozzle outlet and measurement method, which is applied in the direction of temperature measurement, heat measurement, and measurement device of moving fluid, which can solve the problems that affect the reliability of measurement results, the flow rate of nozzle outlet is rarely used, and the requirements for measurement objects are high.
Active Publication Date: 2022-06-07
NORTHWESTERN POLYTECHNICAL UNIV
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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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[0050] The present embodiment is a method for measuring the average Mach number at the nozzle outlet, which includes the following steps:
[0051] Step 1: Determine the throat area A 1 :
[0052] By measuring the width w of the nozzle throat section 1 and the nozzle height h, the throat area A of the nozzle is obtained 1 , namely A 1 =w×h;
[0053] Step 2: The total temperature T of the airflow at the inlet of the nozzle 0 * Measurement:
[0054] A total temperature measuring point 10 is arranged at any position in the middle of the inner surface of the air inlet cavity 7; a hole is machined on the shell of the air intake cavity, and the hole corresponds to the total temperature measuring point. The total temperature probe is installed into the air inlet cavity through the hole, and the vertical distance between the end of the total temperature probe and the total temperature measuring point is 5 mm. The total temperature T of the airflow at the nozzle inlet is measured...
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A method for measuring the average Mach number at the nozzle outlet, based on the indirect measurement of the average Mach number Ma at the nozzle outlet based on the measurement of pressure, temperature and mass flow rate, by measuring the total temperature T of the nozzle inlet airflow 0 * , Nozzle outlet static pressure P 1 The average Mach number Ma at the outlet of the nozzle is obtained from the mass flow rate m of the air flow passing through the nozzle, without inserting the measuring instrument into the high-speed flow field at the nozzle outlet, which reduces the disturbance to the flow field. Compared with the method of obtaining the average Mach number Ma at the nozzle outlet through the laser Doppler flow meter LDV and the particle image velocimeter PIV, the present invention only needs to arrange the total temperature measuring point at the nozzle inlet, and arrange the static pressure measuring point at the nozzle outlet. point, and measure the flow through the nozzle, which is relatively inexpensive to measure and does not require adding solid particles to the flow field. The maximum deviation between the average Mach number Ma at the nozzle outlet calculated by this method and the numerical calculation result of CFD is not more than 6.2%.
Description
technical field [0001] The invention relates to the application field of an aero-engine pre-swirling air supply system, in particular to a method for measuring the average Mach number at the outlet of a pre-swirling nozzle. Background technique [0002] As an important part of the pre-swirl air supply system of aero-engine, the function of the pre-swirl nozzle 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 circumferential 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 achieved. [0003] For an adiabatic pre-swirling system and th...
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IPC IPC(8): G01M13/00G01L15/00G01K13/024G01F1/76G06F30/28G06F113/08G06F119/08G06F119/14
CPCG01M13/00G01K13/02G01F1/76G01L15/00G06F30/28G06F2113/08G06F2119/08G06F2119/14Y02T90/00
Inventor 刘高文龚文彬冯青
Owner NORTHWESTERN POLYTECHNICAL UNIV