Engineering topics
Johnson, R. C.
Publications and source records attributed to Johnson, R. C..
Things That Work: Roles and Services of SPDF
The current Heliophysics Science Data Management Policy (HpSDMP) defines the roles of the Space Physics Data Facility (SPDF) project as a heliophysics active Final Archive (aFA), a focus for critical data infrastructure services and a center of excellence for data and ancillary information services. This presentation will highlight (1) select current SPDF activities, (2) the lessons we are continuing to learn in how to usefully serve the the heliophysics science community and (3)SPDF's programmatic emphasis in the coming year. In cooperation with the Heliophysics Virtual discipline Observatories (VxOs), we are working closely with current, and with upcoming missions such as RBSP and MMS, to define effective approaches to ensure the long-term availability and archiving of mission data, as well as how SPDF services can complement active mission capabilities. We are working to make the Virtual Space Physics Observatory (VSPO) service comprehensive in all significant and NASA relevant heliophysics data. We will highlight a new CDAWeb interface, a faster SSCWeb, availability of our data through VxO services such as Autoplot, a new capability to easily access our data from within IDL and continuing improvements to CDF including better handling of leap seconds.
Calculation of supersonic stream parameters of a real gas from measurable quantities using FORTRAN 4 routines
Sets of routines are presented that calculate such real-gas supersonic stream properties as velocity, density, enthalpy, entropy, and isentropic exponent. Two alternative sets of measurements are assumed: (1) stagnation pressure, stagnation temperature, and the pressure on the surface of a static-pressure wedge; or (2) pressure and temperature in a plenum upstream of a supersonic nozzle and the stagnation pressure at the exit of this nozzle. The routines are applicable to any gas whose properties are known. Explicit routines are presented for determining these properties for air, nitrogen, oxygen, normal hydrogen, para-hydrogen, helium, argon, steam, methane, and natural gas.
Total-pressure measurement in pulsating flows
Pneumatic-type probe was used as comparison instrument with total pressure tubes to determine true average pressure and, thus, to determine if nonlinear averaging effects were significant. Since pneumatic probe is more complicated to use than a total-pressure tube, it is used only as a comparison instrument to determine extent of averaging effects.
Computer program for natural gas flow through nozzles
Subroutines, FORTRAN 4 type, were developed for calculating isentropic natural gas mass flow rate through nozzle. Thermodynamic functions covering compressibility, entropy, enthalpy, and specific heat are included.
Total-pressure averaging in pulsating flows.
A number of total-pressure tubes were tested in a nonsteady flow generator in which the fraction of period that pressure is a maximum is approximately 0.8, thereby simulating turbomachine-type flow conditions. Most of the tubes indicated a pressure which was higher than the true average. Organ-pipe resonance which further increased the indicated pressure was encountered with the tubes at discrete frequencies. There was no obvious combination of tube diameter, length, and/or geometry variation used in the tests which resulted in negligible averaging error. A pneumatic-type probe was found to measure true average pressure and is suggested as a comparison instrument to determine whether nonlinear averaging effects are serious in unknown pulsation profiles.
Total pressure averaging in pulsating flows
A number of total-pressure tubes were tested in a non-steady flow generator in which the fraction of period that pressure is a maximum is approximately 0.8, thereby simulating turbomachine-type flow conditions. Most of the tubes indicated a pressure which was higher than the true average. Organ-pipe resonance which further increased the indicated pressure was encountered within the tubes at discrete frequencies. There was no obvious combination of tube diameter, length, and/or geometry variation used in the tests which resulted in negligible averaging error. A pneumatic-type probe was found to measure true average pressure, and is suggested as a comparison instrument to determine whether nonlinear averaging effects are serious in unknown pulsation profiles. The experiments were performed at a pressure level of 1 bar, for Mach number up to near 1, and frequencies up to 3 kHz.
Tables of critical-flow functions and thermodynamic properties for methane and computational procedures for both methane and natural gas
Procedures for calculating the mass flow rate of methane and natural gas through nozzles are given, along with the FORTRAN 4 subroutines used to make these calculations. Three sets of independent variables are permitted in these routines. In addition to the plenum pressure and temperature, the third independent variable is either nozzle exit pressure, Mach number, or temperature. A critical-flow factor that becomes a convenient means for determining the mass flow rate of methane through critical-flow nozzles is tabulated. Other tables are included for nozzle throat velocity and critical pressure, density, and temperature ratios, along with some thermodynamic properties of methane, including compressibility factor, enthalpy, entropy, specific heat, specific-heat ratio, and speed of sound. These tabulations cover a temperature range from 120 to 600 K and pressures to 3 million N/sq m.
Real-gas effects in flow metering
Real gas mass flow rate computation through sonic nozzle
Real-gas effects in the flow of methane and natural gas through critical-flow nozzles
Methane and natural gas flow through critical flow nozzles, calculating real gas effects on mass flow rate
A set of FORTRAN 4 routines used to calculate the mass flow rate of natural gas through nozzles
Set of FORTRAN 4 subroutines to calculate mass flow rate of natural gas through nozzles, also thermodynamic functions such as compressibility factor, entropy, enthalpy, and specific heat
Real gas effects in flow metering
Real gas corrections to gas flow computations for sonic nozzles
Real gas effects in the flow of methane and natural gas through critical flow nozzles
Equations for mass flow of methane and natural gas mixtures through critical flow nozzles, including real gas effects
Calculations of the Flow of Natural Gas Through Critical Flow Nozzles
Calculation of natural gas flow through critical flow nozzles
Natural gas flow through critical nozzles
Empirical method for calculating both the mass flow rate and upstream volume flow rate through critical flow nozzles is determined. Method requires knowledge of the composition of natural gas, and of the upstream pressure and temperature.
Calculations of the flow of natural gas through critical flow nozzles
Mass flow rate calculation of methane and natural gas mixtures through critical flow nozzles
High pressure real gas effects for helium and nitrogen
Critical flow factor is calculated that permits the isentropic mass-flow rate of the gases through critical flow nozzles to be calculated from plenum conditions. Results include nozzle throat velocity, compressibility factor, entropy, enthalpy, specific heat, and ratios of throat to plenum pressure, density, and temperature.
Computer program for high pressure real gas effects
Computer program obtains the real-gas isentropic flow functions and thermodynamic properties of gases for which the equation of state is known. The program uses FORTRAN 4 subroutines which were designed for calculations of nitrogen and helium. These subroutines are easily modified for calculations of other gases.