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Hueser, J. E.

Publications and source records attributed to Hueser, J. E..

14 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Plume flowfield analysis of the shuttle primary Reaction Control System (RCS) rocket engine

A solution was generated for the physical properties of the Shuttle RCS 4000 N (900 lb) rocket engine exhaust plume flowfield. The modeled exhaust gas consists of the five most abundant molecular species, H2, N2, H2O, CO, and CO2. The solution is for a bare RCS engine firing into a vacuum; the only additional hardware surface in the flowfield is a cylinder (=engine mount) which coincides with the nozzle lip outer corner at X = 0, extends to the flowfield outer boundary at X = -137 m and is coaxial with the negative symmetry axis. Continuum gas dynamic methods and the Direct Simulation Monte Carlo (DSMC) method were combined in an iterative procedure to produce a selfconsistent solution. Continuum methods were used in the RCS nozzle and in the plume as far as the P = 0.03 breakdown contour; the DSMC method was used downstream of this continuum flow boundary. The DSMC flowfield extends beyond 100 m from the nozzle exit and thus the solution includes the farfield flow properties, but substantial information is developed on lip flow dynamics and thus results are also presented for the flow properties in the vicinity of the nozzle lip.

Hueser, J. E.↗
NASA NTRS1985

Shuttle vertical fin flowfield by the direct simulation Monte Carlo method

The flow properties in a model flowfield, simulating the shuttle vertical fin, determined using the Direct Simulation Monte Carlo method. The case analyzed corresponds to an orbit height of 225 km with the freestream velocity vector orthogonal to the fin surface. Contour plots of the flowfield distributions of density, temperature, velocity and flow angle are presented. The results also include mean molecular collision frequency (which reaches 1/60 sec near the surface), collision frequency density (approaches 7 x 10 to the 18/cu m sec at the surface) and the mean free path (19 m at the surface).

Hueser, J. E.↗
NASA NTRS1985

Rocket nozzle lip flow by direct simulation Monte Carlo method

The flow in the immediate vicinity of a rocket nozzle lip has been analyzed, and the results are presented. A rapid change in gas composition is observed in the flow around the lip depending principally on species molecular mass and local flow angle. The divergence of axial and radial temperatures indicating breakdown of translational equilibrium is observed in the results.

Hueser, J. E.↗
NASA NTRS1984

Analysis of large solid propellant rocket engine exhaust plumes using the direct simulation Monte Carlo method

A new solution procedure has been developed to analyze the flowfield properties in the vicinity of the Inertial Upper Stage/Spacecraft during the 1st stage (SRMI) burn. Continuum methods are used to compute the nozzle flow and the exhaust plume flowfield as far as the boundary where the breakdown of translational equilibrium leaves these methods invalid. The Direct Simulation Monte Carlo (DSMC) method is applied everywhere beyond this breakdown boundary. The flowfield distributions of density, velocity, temperature, relative abundance, surface flux density, and pressure are discussed for each species for 2 sets of boundary conditions: vacuum and freestream. The interaction of the exhaust plume and the freestream with the spacecraft and the 2-stream direct interaction are discussed. The results show that the low density, high velocity, counter flowing free-stream substantially modifies the flowfield properties and the flux density incident on the spacecraft. A freestream bow shock is observed in the data, located forward of the high density region of the exhaust plume into which the freestream gas does not penetrate. The total flux density incident on the spacecraft, integrated over the SRM1 burn interval is estimated to be of the order of 10 to the 22nd per sq m (about 1000 atomic layers).

Hueser, J. E.↗
NASA NTRS1981

Direct simulation Monte Carlo technique for modeling of the environment in the vicinity of the Space Shuttle Orbiter

A program for analyzing the flowfield parameters in the neighborhood of the Space Shuttle Orbiter has been developed. The program uses the direct simulation Monte Carlo method, which is a completely probabilistic Monte Carlo technique capable of analyzing 3-dimensional steady or unsteady flow with prescribed internal and external boundary conditions. The freestream flux densities incident on the external flowfield boundaries are calculated from the drifting Maxwellian gas properties of the freestream. The flux entering the flowfield from the internal boundary is calculated from the outgassing flux density distribution over the Shuttle external surface and the prescribed discrete source fluxes. This technique produces a numerical flowfield solution which is the probabilistic equivalent of a complete solution of the time-dependent, 3-dimensional Boltzmann equation. Flowfield results are presented for the following configurations: (1) Shuttle angles of attack of 0 and 90 deg, (2) freestream density 10 to the 9th - 10 to the 11th per cu cm, (3) Shuttle outgassing flux density, and (4) operation of the aft downfiring vernier Reaction Control System (RCS) engine. Results are presented for column density distribution of outgassed and engine species and for the flux density of outgassed and engine species incident on the Shuttle bay and the windshield.

Melfi, L. T., Jr.↗
NASA NTRS1977

Effect of experiments on the density distribution in a molecular shield

A steady-state, collisionless flow analysis has been made of the density distribution within a hemisphere-disk system due to independent, uniformly distributed internal gas sources. The model may be used to estimate the density within a molecular shield, deployed from the Shuttle Orbiter, which contains internal experiments having a prescribed gas source. Contour plots of the density distribution within the system are presented for disk-to-hemisphere radius ratios of 0.1, 0.3, 0.5, and 0.7, and for disk-to-hemisphere surface emission flux density ratios of 0.01, 1, and 100. The hemisphere-disk system is compared to the empty hemisphere and it is found that if the disk emission flux density is the same as the hemisphere and the disk radius is not greater than one-third of the hemisphere radius, the increase in density at the center of the hemisphere-disk system is less than 50%.

Hueser, J. E.↗
NASA NTRS1976

Molecular beam mass spectrometer development

An analytical model, based on the kinetics theory of a drifting Maxwellian gas is used to determine the nonequilibrium molecular density distribution within a hemispherical shell open aft with its axis parallel to its velocity. The concept of a molecular shield in terrestrial orbit above 200 km is also analyzed using the kinetic theory of a drifting Maxwellian gas. Data are presented for the components of the gas density within the shield due to the free stream atmosphere, outgassing from the shield and enclosed experiments, and atmospheric gas scattered off a shield orbiter system. A description is given of a FORTRAN program for computating the three dimensional transition flow regime past the space shuttle orbiter that employs the Monte Carlo simulation method to model real flow by some thousands of simulated molecules.

Brock, F. J.↗
NASA NTRS1976

Molecular shield - An orbiting low-density materials laboratory

Analysis of a molecular shield orbited at 200 km utilizes the kinetic theory of a drifting Maxwellian gas, applied to a hemispherical shell geometry containing internal sources. The molecular shield provides very low gas density conditions for materials experiments at low gravity, while the hemispherical geometry minimizes the internal surface/volume ratio. Deployment of the shield in orbit is described. Contributions to density by shield outgassing, by experiment outgassing, and by interaction with the orbiter are discussed separately. A jettisonable closure plate sealing the hemisphere minimizes any risk of experiment contamination during deployment.

Melfi, L. T., Jr.↗
NASA NTRS1976

Theoretical analysis of the density within an orbiting molecular shield

An analytical model based on the kinetic theory of a drifting Maxwellian gas is used to determine the nonequilibrium molecular density distribution within a hemispherical shell open aft with its axis parallel to its velocity. Separate numerical results are presented for the primary and secondary density distribution components due to the drifting Maxwellian gas for speed ratios between 2.5 and 10. An analysis is also made of the density component due to gas desorbed from the wall of the hemisphere, and numerical results are presented for the density distribution. It is shown that the adsorption process may be completely ignored. The results are applicable to orbital trajectories in any planet-atmosphere system and interplanetary transfer trajectories. Application to the earth's atmosphere is mentioned briefly.

Hueser, J. E.↗
NASA NTRS1972

Thermospheric temperature measurement technique.

A method for measurement of temperature in the earth's lower thermosphere from a high-velocity probes is described. An undisturbed atmospheric sample is admitted to the instrument by means of a free molecular flow inlet system of skimmers which avoids surface collisions of the molecules prior to detection. Measurement of the time-of-flight distribution of an initially well-localized group of nitrogen metastable molecular states produced in an open, crossed electron-molecular beam source, yields information on the atmospheric temperature. It is shown that for high vehicle velocities, the time-of-flight distribution of the metastable flux is a sensitive indicator of atmospheric temperature. The temperature measurement precision should be greater than 94% at the 99% confidence level over the range of altitudes from 120-170 km. These precision and altitude range estimates are based on the statistical consideration of the counting rates achieved with a multichannel analyzer using realistic values for system parameters.

Hueser, J. E.↗
NASA NTRS1971

Wind tunnel mass spectrometer design study

The sampling probe to measure the free stream gas composition in a hypersonic wind tunnel is described. Using a free expansion of the continuum flow, a series of sampling inlet-pumping stages is evaluated. Mass analysis is carried out with a quadrupole mass spectrometer employing a crossed electron beam, molecular beam ion source, and an off-axis electron multiplier. The spatial distribution of the sampled molecular flux and the pumping requirements are evaluated for varying inlet conditions of gas density and flow velocity. The signal-to-noise ratio of the molecular beam formed by this series of coaxial inlets is also determined. The signal-to-noise ratio of the unscattered flux is sufficiently high that an unambiguous determination of the beam composition and of the free stream gas properties can be made. The magnitude of the detected signal is sufficiently high that measurement of trace constituents two orders of magnitude below the primary beam signal can be made.

Hueser, J. E.↗