Flowmeter calibration system and method for cryogenic propellant rocket engine

A flowmeter calibration method for a cryogenic propellant rocket engine, comprising the following steps:

• step 1:
• in-situ calibration of a weighing unit
• step 1.1:
• filling, by a weighing and filling recovery unit (15), collection containers (11) with cryogenic mediums, and recovering, when a filling liquid level in each collection container (11) reaches 70% or above and temperatures of the cryogenic mediums in the collection containers (11) are <5° C., the cryogenic mediums in the collection containers (11) to a quick recovery container (14);
• step 1.2:
• recording a zero position of a load cell (32) and a total mass mtotal of weights (38) on a weighing device;
• step 1.3:
• unloading, according to a usable range of the load cell (32), weights with a preset mass m0 on each lever (36), recording an output value V of the load cell (32) and the mass m of the remaining weights, on this basis, unloading the weights with the preset mass m0 again, recording the output value V of the load cell (32) and the mass m of the remaining weights, and in this way, unloading the weights with the mass m0 for M times, and recording M groups of data totally, wherein M≥5, m0=F/Mg, F is a maximum range of the load cell, and g is an acceleration of gravity;
• and
• step 1.4:
• repeating step 1.3 for K times, wherein K≥2, and performing least squares fit on recorded ((K+1)×M) groups of data to obtain a corresponding relationship between V and (mtotal−m), so as to complete the in-situ calibration of the weighing unit;
• step 2:
• precooling of a cryogenic medium in-situ calibration system
• precooling the collection containers (11) and a first pipeline in front of a container (1) and a supply pipeline manual valve sequentially and cooling a second pipeline and vertical branch pipes (100) behind the supply pipeline manual valve (9) by the cryogenic mediums;
• requiring that a difference between a temperature of a previous precooling area and temperatures of the cryogenic mediums under a standard atmospheric pressure is less than 5° C. before the precooling of a next precooling area;
• closing a calibration flow adjusting manual valve (9) after cooling of the second pipeline and the vertical branch pipes (100) is completed, and draining a pipeline system at a down stream of the calibration flow adjusting manual valve (9), so as to realize the precooling of the cryogenic medium in-situ calibration system;
• step 3:
• in-situ calibration of a container
• step 3.1:
• closing a second isolation valve (13), opening a first isolation valve (4), and filling the container (1) by a container filling unit (2);
• step 3.2:
• gradually opening the calibration flow adjusting manual valve (9) according to a liquid level drop height required to be calibrated for the container (1), slowly discharging the cryogenic mediums in the container (1) to the collection containers (11), weighing each collection container (11) by using the weighing device, calculating a volume corresponding to each liquid level drop height in the container (1), and repeating for at least one time to complete calibration of the container (1);
• and
• opening, after weighing is completed each time, the second isolation valve (13) to discharge the weighed cryogenic mediums from the collection containers (11);
• and
• step 4:
• calibration of a reference flowmeter
• step 4.1:
• closing the second isolation valve (13), or removing an isolation pipeline (12) and a downstream pipeline thereof;
• closing the first isolation valve (4) and the calibration flow adjusting manual valve (9), and filling the container (1) by the container filling unit (2);
• and
• step 4.2:
• opening the first isolation valve (4) and a calibration pneumatic valve (99), discharging the cryogenic mediums from the weighing and filling recovery unit (15) after passing through the supply pipeline and the collection containers (11), recording the volume of the cryogenic mediums decreasing in the container (1) in the same time period many times, calculating an average flow rate of the supply pipeline in this time period, and calibrating a flow rate of the reference flowmeter (7) by the average flow rate.