Design and Operation of a High-Accuracy Calibration Stand for Cryogenic Flowmeters
One of the current problems associated with the use of cryogenic fuels and oxidizers in rocket engine testing is that of accurately determining propellant flow rates, thereby providing essential information for the prediction of thrust and specific impulse. While many diversified approaches are being investigated for the measurement of propellant flow rates ranging from the now familiar turbine-type flowmeter to the more exotic. magnetic and ultrasonic-type flowmeters, all of these systems have a common problem; i.e., even though a highly accurate flowmeter may be developed, the limiting factor is the overall system accuracy including the error in calibrating the flowmeter. In the past, high flow-open type flowmeter test stands have been widely used in calibration of flow measuring devices with non-cryogenic fluids, However, the calibration of flowmeters using cryogenic fluids which are subjected to rapid boil-off precludes the use of a system which is open to ambient conditions. In addition, cryogenic fluids inherently exhibit significant density changes as the temperature of the fluid varies. Inasmuch as most cryogenic systems are maintained under a pressure sufficient to insure subcooling of the liquid, the temperature—density variation could occur without cavitation but still present unique problems in determining the flow rate.
KeywordsTest Section Test Fluid Liquid Oxygen Magnetic Switch Flow Control Valve
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