Compressible flow across shaft face seals
Compressible flow across shaft face seals and narrow slots, examining fluid inertia, viscous friction and entrance losses
Johnson, R. L.↗
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Quasi-one-dimensional compressible flow across face seals and narrow slots. 1: Analysis
An analysis is presented for compressible fluid flow across shaft face seals and narrow slots. The analysis includes fluid inertia, viscous friction, and entrance losses. Subsonic and choked flow conditions can be predicted and analyzed. The model is valid for both laminar and turbulent flows. Results agree with experiment and with solutions which are more limited in applicability. Results show that a parallel film can have a positive film stiffness under choked flow conditions.
Zuk, J.↗
Interaction between an upstream facing wall jet and a supersonic stream
The flow field resulting from the interaction of an upstream facing wall jet with a supersonic counterflowing stream has been investigated. A flow field model and the main parameters governing the phenomena were determined from quantitative and qualitative experimental observations. Experimental results for different ranges of the main parameters are presented. A theoretical analysis was performed to describe the flow field in the mixing region between the two counterflowing streams. The results obtained by applying a locally similar solution compare favorably with the experimentally measured values. Large values of jet penetration were obtained with a high subsonic or low supersonic jet; large interaction forces are characteristics of higher supersonic injections. For the case of large penetration the cooling effectiveness presented as a function of the main parameters indicates the possibility of interacting cooling applications.
Piva, R.↗
Heat transfer at reattachment of a compressible flow over a backward facing step with a suction slot.
A simplified model is suggested for engineering estimates of heat transfer in the vicinity of reattachment for the case of supersonic flow over a backward facing step with a suction slot. The presented approach gives a closed-form approximate solution which is shown to be in satisfactory agreement with experimental results for the case of no mass transfer, and is expected to predict the effect of mass transfer in the case of suction.
Telionis, D. P.↗
Design and flight testing of a nullable compressor face rake
A compressor face rake with an internal valve arrangement to permit nulling was designed, constructed, and tested in the laboratory and in flight at the NASA Flight Research Center. When actuated by the pilot in flight, the nullable rake allowed the transducer zero shifts to be determined and then subsequently removed during data reduction. Design details, the fabrication technique, the principle of operation, brief descriptions of associated digital zero-correction programs and the qualification tests, and test results are included. Sample flight data show that the zero shifts were large and unpredictable but could be measured in flight with the rake. The rake functioned reliably and as expected during 25 hours of operation under flight environmental conditions and temperatures from 230 K (-46 F) to greater than 430 K (314 F). The rake was nulled approximately 1000 times. The in-flight zero-shift measurement technique, as well as the rake design, was successful and should be useful in future applications, particularly where accurate measurements of both steady-state and dynamic pressures are required under adverse environmental conditions.
Holzman, J. K.↗
Quasi-one-dimensional compressible flow across face seals and narrow slots. 2: Computer program
A computer program is presented for compressible fluid flow with friction across face seals and through narrow slots. The computer program carries out a quasi-one-dimensional flow analysis which is valid for laminar and turbulent flows under both subsonic and choked flow conditions for parallel surfaces. The program is written in FORTRAN IV. The input and output variables are in either the International System of Units (SI) or the U.S. customary system.
Zuk, J.↗
Flight-measured base pressure coefficients for thick boundary-layer flow over an aft-facing step for Mach numbers from 0.4 to 2.5
A 0.56-inch thick aft-facing step was located 52.1 feet from the leading edge of the left wing of an XB-70 airplane. A boundary-layer rake at a mirror location on the right wing was used to obtain local flow properties. Reynolds numbers were near 10 to the 8th power, resulting in a relatively thick boundary-layer. The momentum thickness ranged from slightly thinner to slightly thicker than the step height. Surface static pressures forward of the step were obtained for Mach numbers near 0.9, 1.5, 2.0, and 2.4. The data were compared with thin boundary-layer results from flight and wind-tunnel experiments and semiempirical relationships. Significant differences were found between the thick and the thin boundary-layer data.
Goecke, S. A.↗
Insert facing tool
A manually actuated tool for facing the exposed end of an insert installed in a honeycomb panel is described. Several cutting bits are held in a round body portion that is rotated around the end of a stud to provide the cutting action. Pressure is adjusted through a spring against the body portion and the surface of the stud by a pressure nut threaded on the stud. A diagram of the components of the device is provided.
Abernathy, W. J.↗
Rearward-facing steps in laminar supersonic flows with and without suction
An experimental investigation of heat-transfer and pressure distributions within regions of laminar separated flows produced by two-dimensional rearward-facing steps has been carried out at freestream Mach numbers of around 4 in the range of step height-to-boundary layer thickness varying from 0.1 to 2.4. With no suction from the separated area, the ratio of the maximum post-step heat transfer to the attached-flow values was less than unity. The maximum heating-rate region was located far downstream of the reattachment plate stagnation point. Mass suction from the separated area increased the local heating rates, this effect was however relatively weak for purely laminar flow conditions and the competing effect of the step height clearly predominated. At step heights comparable with boundary-layer thickness, even removing the entire approaching boundary layer was not sufficient to raise the post-step heating rates above the flat-plate values.
Jakubowski, A. K.↗
Application of the MOS-C-V technique to determine impurity concentrations and surface parameters on the diffused face of silicon solar cells
The feasibility of using the MOS C-V technique to obtain information regarding impurity and surface state concentrations on the diffused face of silicon solar cells with Ta2O5 coatings is studied. Results indicate that the MOS C-V technique yields useful information concerning surface parameters which contribute to the high, efficiency limiting, surface recombination velocities on the n+ surface of silicon solar cells.
Weinberg, I.↗
Effect of inlet ingestion of a wing tip vortex on compressor face flow and turbojet stall margin
A two-dimensional inlet was alternately mated to a coldpipe plug assembly and a J85-GE-13 turbojet engine, and placed in a Mach 0.4 stream so as to ingest the tip vortex of a forward mounted wing. Vortex properties were measured just forward of the inlet and at the compressor face. Results show that ingestion of a wing tip vortex by a turbojet engine can cause a large reduction in engine stall margin. The loss in stall compressor pressure ratio was primarily dependent on vortex location and rotational direction and not on total-pressure distortion.
Mitchell, G. A.↗
Survey of projected growth and problems facing air transportation, 1975 - 1985
Results are presented of a survey conducted to determine the current opinion of people working in air transportation demand forecasting on the future of air transportation over the next ten years. In particular, the survey included questions on future demand growth, load factor, fuel prices, introduction date for the next new aircraft, the priorities of problems facing air transportation, and the probability of a substantial change in air transportation regulation. The survey participants included: airlines, manufacturers, universities, government agencies, and other organizations (financial institutions, private research companies, etc.). The results are shown for the average responses within the organization represented as well as the overall averages.
Williams, L. J.↗
The two faces of Iapetus
Radiometric and photometric observations of Iapetus are described, and a model is developed for the albedo distribution consistent with the visual light curves, color variations, and radiometric flux curve. The 20-micron infrared observations show that the radiometric variation differs by about 180 deg in phase from the visual light curve and has a peak-to-peak amplitude of about a factor of two, while the linear phase coefficient of the light curve varies, as the satellite rotates, from 0.028 to 0.068 mag/deg. Determination of the albedo distribution is described, and it is found to be characterized by a dark area covering most of the leading hemisphere, a bright trailing hemisphere, and a bright south polar cap. The radius is approximated as 800 to 850 km, and the mean geometric albedos for the light and dark faces are estimated as 0.35 and 0.07, respectively.
Morrison, D.↗
Application of the MOS C-V technique to determine impurity concentrations and surface parameters on the diffused face of silicon solar cells
An experimental and theoretical investigation of the feasibility of using the MOS C-V (capacitance-voltage) technique to determine impurity and surface state concentrations on the diffused face of Si solar cells with Ta2O5 coatings. Impurity concentration 10 A from the diffused surface is found to be 2.9 times 10 to the 20th power per cu cm. Charge density in surface and oxide states is 2.1 times 10 to the 13th power per sq cm. These data agree with theoretical predictions.-
Weinberg, I.↗
Hydrodynamic lubrication of face seals
Two companion reports describe possible primary-seal geometries and face-seal angular-misalinement geometry.
Ludwig, L. P.↗
FORTRAN Automated Code Evaluation System (FACES) functional characteristics, version 2, Mod 0
A detailed description of FACES acceptable FORTRAN is presented along with FORTRAN front end codes. Queries are also described, and flag file data are presented.
Source record↗
Face-seal lubrication. 2: Theory of response to angular misalignement
A theoretical analysis was made of a hypothetical seal operating mode. The hypothetical seal model provides for three degrees of primary ring motion and includes the force and moments induced by primary ring response to seat angular misalignment. This ring response causes a relative angular misalignment between the faces of the primary seal. Hydrodynamic pressure generation is produced by this misalignment. The analysis is based on the Reynolds equation in short bearing form and on a balance of forces and moments that arise from hydrodynamic and secondary seal friction effects. A closed form solution was obtained that can be solved for film thickness and relative angular misalignment.
Ludwig, L. P.↗
Analysis of neutrally stable atmospheric flow over a two-dimensional forward facing step
A mathematical model describing ground-wind induced flow fields around surface obstructions such as buildings, bridges or other man-made structures is presented. The Navier-Stokes equations with a two-equation turbulence model are used to analyze the flow over a two-dimensional forward facing step. A study of the assumed logarithmic approach velocity profile shows that an increase of surface roughness produces a rise to higher turbulence levels in the shear layer originating from the step corner. This rise leads to higher Reynolds stress and to faster reattachment of the separated flow.
Bitte, J.↗