An accurate determination of fluid flow in a cryogenic propulsion environment is difficult under the best of circumstances. The extreme thermal environment increases the mechanical constraints, and
variable density conditions create havoc with traditional flow measurement schemes. Presented here are secondary results of cryogenic testing of an all-optical sensor capable of a mass flow measurement by directly interrogating the fluid's density state and a determination of the fluid's velocity. The sensor's measurement basis does not rely on any inherent assumptions as to the state of the fluid flow (density or otherwise). The fluid sensing interaction model will be discussed. Current test and evaluation data and future development work will be presented.
Pressure sense lines, as employed in the measurement of rocket engine test firings, can propagate the time-domain pressure signal out of hostile regions and allow instrumentation with pressure transducers. In such applications, it is necessary to correct the data to account for attenuation and resonance due to the sense line. One technique for doing so is the application of Fourier transform theory to obtain the transfer function of the sense line. Various techniques for obtaining the transfer function are explored, including the use of Gaussian noise, single frequency sweeps, and impulse signals as input functions. The transfer function thus obtained is mathematically fit, scaled, and validated against a related system.
Accurate and reliable multiphase flow measurements are needed for liquid propulsion systems. Existing volumetric flow meters are adequate for flow measurements with well-characterized, clean liquids and gases. However, these technologies are inadequate for multiphase environments, such as cryogenic fluids. Although, properly calibrated turbine flow meters can provide highly accurate and repeatable data, problems are still prevalent with multiphase flows. Limitations are thus placed on the applicability of intrusive turbine flow meters.