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At least 1,135 records · Page 63
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

SRB/SLEEC (Solid Rocket Booster/Shingle Lap Extendible Exit Cone) feasibility study, volume 1

A preliminary design and analysis was completed for a SLEEC (Shingle Lap Extendible Exit Cone) which could be incorporated on the Space Transportation System (STS) Solid Rocket Booster (SRB). Studies were completed which predicted weights and performance increases and development plans were prepared for the full-scale bench and static test of SLEEC. In conjunction with the design studies, a series of supporting analyses were performed to assure the validity and feasibility of performance, fabrication, cost, and reliability for the selected design. The feasibility and required amounts of bench, static firing, and flight tests considered necessary for the successful incorporation of SLEEC on the Shuttle SRBs were determined. Preliminary plans were completed which define both a follow on study effort and a development program.

Baker, William H., Jr.↗
NASA NTRS1986

SRB/SLEEC (Solid Rocket Booster/Shingle Lap Extendible Exit Cone) feasibility study, volume 2. Appendix A: Design study for a SLEEC actuation system

The results are presented of a design feasibility study of a self-contained (powered) actuation system for a Shingle Lap Extendible Exit Cone (SLEEC) for Transportation System (STS). The evolution of the SLEEC actuation system design is reviewed, the final design concept is summarized, and the results of the detailed study of the final concept of the actuation system are treated. A conservative design using proven mechanical components was established as a major program priority. The final mechanical design has a very low development risk since the components, which consist of ballscrews, gearing, flexible shaft drives, and aircraft cables, have extensive aerospace applications and a history of proven reliability. The mathematical model studies have shown that little or no power is required to deploy the SLEEC actuation system because acceleration forces and internal pressure from the rocket plume provide the required energies. A speed control brake is incorporated in the design in order to control the rate of deployment.

Thompson, D. S.↗
NASA NTRS1988

Computational validation of a parabolized Navier-Stokes solver on a sharp-nose cone at hypersonic speeds

Perfect gas computational results from a newly-developed upwind, parabolized Navier-Stokes (PNS) solver are compared with an existing set of experimental laminar results for a 10-deg half-angle circular cone at freestream Mach number of 7.95. Comparisons were performed with surface pressure and heat transfer data, as well as with flowfield pitot measurements. The PNS code predicted the surface quantities accurately up through 20-deg angle-of-attack, including crossflow separation, and correctly defined the location of the bow shock and the edge of the boundary layer. The importance of cell Reynolds number, grid density, and thermal boundary conditions to the accurate prediction of the flowfield are examined through numerical emamples.

Huebner, Lawrence D.↗
NASA NTRS1989

Study of hypersonic flow past sharp cones

Calculations using the direct simulation Monte Carlo (DSMC) method of Bird for flow past sharp cones in the near continuum to free molecule flow regime are presented and compared with experiment. It is found that results are sensitive to the grid and the interaction potential. Moreover, the time counter method was found to be as accurate as other methods when the solution is grid independent. Finally, the results show that the effects of the wake on the forebody surface properties are minimal.

Taylor, Jeff C.↗
NASA NTRS1989

Experimental and computational results for 5 degree blunt cones with shock generators at high velocity

Experiments and computations have been performed under laminar conditions in air on 5-deg blunt cones at velocities of 5 km/s and 6 km/s and at Reynolds numbers of 100,000 and 1 million. The computations were performed using ideal-, equilibrium- and nonequilibrium-chemistry models for air. At the conditions of the tests, the aerodynamic coefficients are sensitive to the real-gas effects present, and both experimental and computational aerodynamic coefficients show real-gas and nonlinear effects. The nonequilibrium computations show that a large amount of oxygen is dissociated in the blunt nose region of the flow and much of the oxygen remains dissociated over the entire length of the body, providing an insight into the source of the observed effects in the aerodynamic coefficients. The experimental and computational shock-shapes are in good agreement.

Strawa, A. W.↗
NASA NTRS1990

Improved tangent-cone method for the Aerodynamic Preliminary Analysis System (APAS) version of the hypersonic arbitrary-body program

The Aerodynamic Preliminary Analysis System (APAS) utilizes a modified version of the Hypersonic Arbitrary-Body Program (HABP) Mark 3 code in its analysis rationale. Four methods are considered for incorporation into the code as the tangent-cone method. The combination of second-order slender body theory and the approximate solution of Hammitt and Murthy shows the best agreement with the exact numerical solutions and is thus included in the APAS production version of the HABP code.

Cruz, Christopher I.↗
NASA NTRS1988

Gas-jet and tangent-slot film cooling tests of a 12.5 deg cone at Mach number of 6.7

Tests were conducted in the Langley 8-Foot High Temperature Tunnel to determine the aerothermal effects of gaseous nitrogen-coolant ejection on a 3-ft base-diameter, 12.5 degree half-angle cone. Free-stream Mach number, total temperature, and unit Reynolds number per foot were 6.7, 3300 deg R, and 1.4 million, respectively. Two coolant ejection noses were tested, an ogive frustum with a forward-facing 0.8-in radius gas-jet tip, and a 3-in radius hemisphere with a 0.243-in high rearward-facing tangent slot. Data include surface pressures and heating rates, shock shapes, and shock-layer profiles; results are compared with no-cooling data obtained with 1-in and 3-in radius solid noses. Surface pressures were reduced with gas-jet ejection but were affected little by tangent-slot ejection. For both gas-jet and tangent-slot ejection, high coolant flow rates reduced heating even far downstream from the region of ejection; however, low coolant rates caused transition to turbulence and increased heating. Shock-layer profiles of pitot pressure, Mach number, and total temperature were reduced for both gas-jet and tangent-slot ejection. Insight into the gas-jet heat-flux mechanisms was obtained by using shock-layer rake data and established, no-cooling, heat-transfer equations.

Nowak, Robert J.↗
NASA NTRS1989

Calculation of asymmetric vortex separation on cones and tangent ogives based on a discrete vortex model

The boundary value problem for vortex separation at zero sideslip on cones and tangent ogives is set up by means of a discrete vortex model. The nonlinear algebraic equations for the boundary value problem admit multiple, physically feasible solutions, including the symmetric and asymmetric vortex solutions. Multiple solutions are proposed as an alternative explanation of the existence of asymmetric vortex separation at zero sideslip.

Chin, Suei↗
NASA NTRS1991

Solar Concentrator Has Wider Cone Of Acceptance

Reflector assembly for concentration of Sunlight onto photovoltaic cell based on Cassegrainian optical system modified to increase allowable error angle between aim and line of sight to Sun. Widening of cone of acceptance reduces degradation of performance caused by surface-slope errors, misalignments between optical components, and non-fully-specular (i.e., partly diffuse) reflectance. Consequent relaxation of aiming and manufacturing tolerances reduces cost and number of rejects in manufacturing and simplify operation.

Kruer, Mark A.↗
NASA NTRS1991

Computed Hypersonic Flow About A Sharp Cone

Report describes mostly computational study of hypersonic flow about sharp cone. Part of continuing effort to understand and predict complicated aerodynamic and heat-transfer phenomena in flows over forebodies of such hypersonic vehicles as Space Shuttle and proposed National Aerospace Plane. Focuses on transition from laminar to turbulent flow, with particular reference to heat-transfer predictions.

Kaul, Upender K.↗
NASA NTRS1991

Three-dimensional computed tomography from interferometric measurements within a narrow cone of views

A theory to determine the properties of a fluid from measurements of its projections was developed and tested. Viewing cones as small as 10 degrees were evaluated, with the only assumption being that the property was space limited. The results of applying the theory to numerical and actual interferograms of a spherical discontinuity of refractive index are presented. The theory was developed to test the practicality and limits of using three-dimensional computer tomography in internal fluid dynamics.

Decker, Arthur J.↗
NASA NTRS1991

Laser transit anemometer and Pitot probe comparative measurements in a sharp cone boundary layer at Mach 4

Laser transit anemometer (LTA) measurements of a 7 degree sharp cone boundary layer were conducted in the Air Force/AEDC Supersonic Tunnel A Mach 4 flow field. These measurements are compared with Pitot probe measurements and tricone theory provided by AEDC staff. Measurements were made both in laminar and turbulent boundary layers of the model. Comparison of LTA measurements with theory showed agreement to better than 1 percent for the laminar boundary layer cases. This level of agreement was obtained after small position corrections, 0.01 to 0.6 mm, were applied to the experimental data sets. Pitot probe data when compared with theory also showed small positioning errors. The Pitot data value was also limited due to probe interference with the flow near the model. The LTA turbulent boundary layer data indicated a power law dependence of 6.3 to 6.9. The LTA data was analyzed in the time (Tau) domain in which it was obtained and in the velocity domain. No significant differences were noted between Tau and velocity domain results except in one turbulent boundary layer case.

Hunter, W. W., Jr.↗
NASA NTRS1990

The inviscid stability of supersonic flow past a sharp cone

The effects of lateral curvature on the development of supersonic laminar inviscid boundary-layer flow on a sharp cone with adiabatic wall conditions are investigated analytically, with a focus on the linear temporal inviscid stability properties. The derivation of the governing equations and of a 'triply generalized' inflexion condition is outlined, and numerical results for freestream Mach number 3.8 are presented in extensive graphs and characterized in detail. A third instability mode related to the viscous mode observed by Duck and Hall (1990) using triple-deck theory is detected and shown to be more unstable and to have larger growth rates than the second mode in some cases. It is found that the 'sonic' neutral mode is affected by the lateral curvature and becomes a supersonic neutral mode.

Duck, Peter W.↗
NASA NTRS1990

Computation and control of asymmetric vortex flow around circular cones using Navier-Stokes equations

The unsteady, compressible, thin-layer and full Navier-Stokes equations are used to numerically simulate steady and unsteady asymmetric, supersonic, locally conical flows around a 5-deg semiapex angle circular cone. The main computational scheme is the implicit, upwind, flux-difference splitting, finite-volume scheme. Comparison of asymmetric flow solutions using the thin-layer and full Navier-Stokes equations is presented and discussed. The implicit, upwind, flux-vector splitting, finite-volume scheme has also been used to solve for the unsteady asymmetric flow with vortex shedding. The unsteady-flow solution using the flux-vector splitting scheme perfectly agrees with the previously obtained solution using the flux-difference splitting scheme. Passive control of asymmetric flows has been demonstrated and studied using sharp- and round-edged, thick and thin strakes.

Kandil, Osama A.↗
NASA NTRS1990

Analysis of cone-derived waveriders by hypersonic small-disturbance theory

Hypersonic small-disturbance theory is used to analyze slender waveriders derived from axisymmetric flows past circular cones. Viscous effects are accounted for by means of laminar boundary-layer theory. The shape of the waverider is determined by specifying the upper freestream surface, from which the lower compression surface can then be obtained. When this is done, the lift, drag, and pitching moment are determined in terms of quadratures over the shock layer in the base plane. They are functions of freestream Mach number, freestream Reynolds number based on the length of the waverider, some measure of slenderness, and other parameters relating to the shape of the waverider. The functional relationships can be cast in terms of similarity laws. The lift-to-drag ratio is determined for a wide range of shapes and parameters.

Rasmussen, Maurice L.↗
NASA NTRS1991

Mach 3.5 boundary-layer transition on a cone at angle of attack

Boundary-layer transition on a sharp 5-deg half-angle cone at incidence was investigated at Mach 3.5 in NASA's Supersonic Low-Disturbance Pilot Tunnel. The tests were conducted with low and high levels of freestream acoustic disturbance, and four angles of attack (alpha/theta-c = 0, 0.12, 0.4, and 0.8). Transition data, obtained with and without significantly reduced freestream acoustic disturbance levels, are compared with conventional ('noisy') wind-tunnel data. It was found that, under quiet flow conditions, there was no significant unit Reynolds number effect, whereas with noisy flow conditions, a significant unit Reynolds number effect was measured on and near the windward ray for alpha/theta-c values 0.4 and 0.8.

King, Rudolph A.↗
NASA NTRS1992

The ionization cone, obscured nucleus, and gaseous outflow in NGC 3281 - A prototypical Seyfert 2 galaxy?

Narrow-band images and long-slit spectroscopy of the central region of the highly inclined Seyfert galaxy NGC 3281 are presented. The image of the continuum-subtracted forbidden 4959 emission line shows a very clear conical morphology for the high-excitation gas. A possible similar structure can also be seen on the other side of the nucleus, but is dimmed by patchy obscuration in the dusk. The continuum images and long-slit spectroscopy are used to derive and map the extinction in the inner regions of NGC 3281; heavy obscuration is found along the present line of sight to the apex of the cone, suggesting that the true nucleus is located at the apex and is obscured. Low-resolution long-slit spectra are used to study the stellar population, which is found to be old, uniform within 2.5 kpc of the nucleus, and typical of the bulges of early-type galaxies. It is suggested that NGC3281 may be another example of a 'hidden' Seyfert 1, even though there is no direct evidence for a broad-line region in this particular galaxy.

Storchi-Bergmann, Thaisa↗