Cryogenic Flow Sensor

An acousto-optic cryogenic flow sensor (CFS) determines mass flow of cryogens for spacecraft propellant management. The CFS operates unobtrusively in a high-pressure, high-flowrate cryogenic environment to provide measurements for fluid quality as well as mass flow rate. Experimental hardware uses an optical plane-of-light (POL) to detect the onset of two-phase flow, and the presence of particles in the flow of water. Acousto-optic devices are used in laser equipment for electronic control of the intensity and position of the laser beam. Acousto-optic interaction occurs in all optical media when an acoustic wave and a laser beam are present. When an acoustic wave is launched into the optical medium, it generates a refractive index wave that behaves like a sinusoidal grating. An incident laser beam passing through this grating will diffract the laser beam into several orders. Its angular position is linearly proportional to the acoustic frequency, so that the higher the frequency, the larger the diffracted angle. If the acoustic wave is traveling in a moving fluid, the fluid velocity will affect the frequency of the traveling wave, relative to a stationary sensor. This frequency shift changes the angle of diffraction, hence, fluid velocity can be determined from the diffraction angle. The CFS acoustic Bragg grating data test indicates that it is capable of accurately determining flow from 0 to 10 meters per second. The same sensor can be used in flow velocities exceeding 100 m/s. The POL module has successfully determined the onset of two-phase flow, and can distinguish vapor bubbles from debris

Optical mass gauge sensor having an energy per unit area of illumination detection

An optical mass gauge sensor is disclosed comprising a vessel having an interior surface which reflects radiant energy at a wavelength at least partially absorbed by a fluid contained within the vessel, an illuminating device for introducing radiant energy at such wavelength into the vessel interior, and, a detector for measuring the energy per unit area of illumination within the vessel created by the radiant energy which is not absorbed by the fluid

Hybrid bearings for turbopumps and the like

In rocket engines power is usually obtained by burning fuel and oxidizer which are mixed, pressurized, and directed to a combustion chamber by means of turbopumps. Roller bearings are generally used in these turbopumps, but because of bearing demands hydrostatic bearings were proposed. The use of such bearings is quite feasible because during flight hydrostatic lubrication can reduce roller bearing wear. A disadvantage of such proposals is that during startup, acceleration, and shutdown high pressure fluids are not available for hydrostatic bearings. The fluid lubrication film is not always present in bearings of turbopumps. During these periods a second bearing is required to carry the load. This requirement suggests the use of hybrid bearings in rocket engine turbopumps. Such duplex bearings were provided, but when their inner races are keyed to the shaft or journal two of them are required. And such duplex bearings do not wear evenly. A hybrid hydrostatic-rolling element bearing was provided wherein the rolling element bearing is locked on the stationary housing rather than on the rotating journal

Force Balance Determination of a Film Riding Seal Using CFD

CFD analysis provides a means of discerning H-seal functionality. H-Seal geometry can be modified to provide smaller or larger operational gap. H-Seal can be installed with large cold clearance and maintain a small operational effective clearance

Application of Dynamic pressure-balanced Seals in a Multi-stage Centrifugal Compressor

LecturesTest results for an ASME Power Test Code 10 (PTC) Type 1 test of a 4,500 psia (310 Bara) discharge pressure gas lift centrifugal compressor outfitted with dynamic pressure-balanced seals at the impeller eyes; shaft interstage and division wall locations are presented and compared to the same testing with conventional labyrinth seals. Both aerodynamic performance and rotor dynamic stability, obtained via operational modal analysis (OMA), are presented. A client’s motivation, along with the design and testing of dynamic pressure-balanced (DPB) seals for turbomachinery are also presented in this paper. With the DPB seals installed the test results indicate 2.8 percent lower power was required for the same head level across the entire range of inlet flows and pressure ratios, when compared to the same testing with conventional labyrinth seals. Rotordynamic stability, obtained via operational modal analysis (OMA), showed the dynamic pressure-balanced (DPB) seals exhibited log decs similar to standard labyrinth seals across the entire range of flows and pressure ratios. The foregoing demonstrates both the aerodynamic and mechanical/rotordynamic integrity of the dynamic pressure-balanced seals for oil and gas, turbomachinery applications

Application of Dynamic pressure-balanced Seals in a Multi-stage Centrifugal Compressor

LectureTest results for an ASME Power Test Code 10 (PTC) Type 1 test of a 4,500 psia (310 Bara) discharge pressure gas lift centrifugal compressor outfitted with dynamic pressure-balanced seals at the impeller eyes; shaft interstage and division wall locations are presented and compared to the same testing with conventional labyrinth seals. Both aerodynamic performance and rotor dynamic stability, obtained via operational modal analysis (OMA), are presented. A client’s motivation, along with the design and testing of dynamic pressure-balanced (DPB) seals for turbomachinery are also presented in this paper. With the DPB seals installed the test results indicate 2.8 percent lower power was required for the same head level across the entire range of inlet flows and pressure ratios, when compared to the same testing with conventional labyrinth seals. Rotordynamic stability, obtained via operational modal analysis (OMA), showed the dynamic pressure-balanced (DPS) seals exhibited log decs similar to standard labyrinth seals across the entire range of flows and pressure ratios. The foregoing demonstrates both the aerodynamic and mechanical/rotordynamic integrity of the dynamic pressure-balanced seals for oil and gas, turbomachinery applications

Hydrogen Compressor Seal Case Study - Utilizing HALO (Non-Contacting, Compliant) Inter-Stage, Impeller Eye, Buffer and Fail-Safe Seals

Case StudyAn end user of a hydrogen compressor in an oil refinery application has identified existing labyrinth seals as a source of compressor inefficiency and a potential cause of rotor- dynamic instability. The objective of this effort was to investigate the applicability of a compliant/non-contacting seal developed for aerospace applications in the 5-stage hydrogen centrifugal compressor. This effort identified the potential seal performance of the compliant seals in the hydrogen compressor application 4 primary locations (shaft seal, impeller eye seal, thrust balance seal and barrier/buffer gas seal)

ABSORPTION SPECTRA OF LIQUID HYDROGEN AND THE DEVELOPMENT OF A NEW OPTICAL MASS GAUGE SENSOR FOR ROCKET FUEL

$^{a}$ E.J. Allin, W.F.J. Hare, and R.E. MacDonald, Phys. Rev. 98, 554 (1955) $^{b}$ A.R.W. McKellar and M.J. Clouter, Can, J. Phys. 72, 51 (1994)Author Institution: Department of Physics, The Ohio State University; Physikalisch-Chemisches Institut, Justus-Liebig-Universit\'{a}t; Justak Research Inc., Justus-Liebig-Universit\'{a}tOnly a few papers on the absorption spectra of liquid hydrogen have been published after its first observation in $1955^{a}$, and none of them addresses vibrational excitations higher than the fundamental band $(4000-5000 cm^{-1})$. The most comprehensive study so far has been performed by McKellar and $Clouter^{b}$, which also includes the spectra of liquid deuterium. The reason for this relative lack of interest in the spectroscopy of liquid hydrogen compared to its solid state counterpart lies in the poor understanding of induced absorption mechanisms for molecules in the liquid phase. We will present the results of our observations of liquid parahydrogen at various orthohydrogen impurity levels in the first $(8000-9600 cm^{-1})$ and second $(11800-13000 cm^{-1})$ overtone regions using a Bruker IFS 120 Fourier transform spectrometer at a resolution of typically 1 $cm^{-1}$ and optical pathlengths up to 34 cm. We will furthermore indicate analogies between the spectrum of the liquid and the corresponding spectrum of the solid phase of hydrogen. Since the second overtone spectrum of liquid hydrogen reaches into the visible wavelength region, this work has been helpful in the current development of an optical mass gauge sensor for rocket fuel under zero-g conditions. The basic priciple of this new device will be presented