NONINVASIVE CRYOGENIC FLOW MEASUREMENT

摘要

Development of noninvasive methods for measuring fluid flow rates and other variables under varyingphysical configurations has been an area of interest of NASA for some time. Noninvasive methods aredesirable for installations requiring backup or redundant measurements or in systems where intrusiveinstallation is difficult or impossible.Noninvasive flowmeters are typically operated in the Doppler or transient-time modes. It is the transienttime mode of operation that has been implemented within the context of this applied research anddevelopment project. In this mode, ultrasonic transducers are situated contiguous to each other, typicallyat one diameter distance. Each transducer alternates in its role as transmitter then receiver in a cyclicalfashion. The received upstream signal is compared to the received downstream signal to derive adifferential time. With this time, the velocity may be measured and volumetric flow through the pipemay be calculated.Noninvasive measurement techniques can be applied to cryogenic rocket oxidants and fuels, particularlyliquid oxygen and liquid hydrogen, with emphasis on flow instrumentation. Flow measurement utilizingnoninvasive measurement techniques offer promise for rocket engine control system instrumentation.Control systems integration is a logical step in the continuation of this research.