Alkali metals boiling and condensing investigations Quarterly progress report no. 13, Jul. 1 - Sep. 30, 1965
Two-phase heat transfer and fluid flow data for potassium under conditions of boiling and condensing
BOILING↗
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Simulation of turbomachinery flows
Significant advancements have been made in the last five years in the ability to model turbomachinery flows of engineering interest. This advancement can be directly attributed to the second generation of supercomputers like the Cray XMP and Cray 2 and advanced instrumentation techniques. Early on, the National Aeronautics and Space Administration Lewis Research Center recognized the potential gains in turbomachinery performance and life that could be achieved by taking advantage of this technology and instituted a comprehensive research program in turbomachinery flow modeling. This activity combined the areas of fluid flow analysis, computational fluid dynamics, and experimental fluid mechanics. As a result of this activity, Lewis has become an internationally recognized leader in turbomachinery flow modeling. Many of the research activities conducted under this program are utilized by industry. The presentation gives an overview of this program and provides sample illustration of simulation performed to date.
Adamczyk, John J.↗
A New Modular Approach for Tightly Coupled Fluid/Structure Analysis
Static aeroelastic computations are made using a C++ executive suitable for closely coupled fluid/structure interaction studies. The fluid flow is modeled using the Euler/Navier Stokes equations and the structure is modeled using finite elements. FORTRAN based fluids and structures codes are integrated under C++ environment. The flow and structural solvers are treated as separate object files. The data flow between fluids and structures is accomplished using I/O. Results are demonstrated for transonic flow over partially flexible surface that is important for aerospace vehicles. Use of this development to accurately predict flow induced structural failure will be demonstrated.
Guruswamy, Guru↗
A new momentum-integral method for treating MHD and simple hydrodynamic entrance flows.
Conducting fluid incompressible flow in entrance of MHD channel by momentum integral method, permitting edge stress existence at boundary layer free stream interface
Schwirian, R. E.↗
A new momentum integral method for MHD channel entrance flows
Conducting fluid incompressible flow in entrance of MHD channel by momentum integral method, permitting edge stress existence at boundary layer free steam interface
Schwirian, R. E.↗
Flow diverter value and flow diversion method
A flow diverter valve applicable to any fluid flow system requiring rapid bleed or bypass is disclosed. Examples of application of the flow diverter valve to a liquid rocket and a turbojet aircraft engine are given. Features of the valve include: (1) an independent fluid source is used to activate the flow diverter valve toward its closed position during its initial stage of travel; (2) the flow diverter port area and size is unlimited and the valve travel is unlimited; and (3) the valve housing is fabricated such that the valve can be a one step valve, a two step valve, or include as many steps as are found desirable.
Arline, S. B.↗
The nonlinear interaction of Tollmien-Schlichting waves and Taylor-Goertler vortices in curved channel flows
It is known that a viscous fluid flow with curved streamlines can support both Tollmien-Schlichting and Taylor-Goertler instabilities. In a situation where both modes are possible on the basis of linear theory a nonlinear theory must be used to determine the effect of the interaction of the instabilities. The details of this interaction are of practical importance because of its possible catastrophic effects on mechanisms used for laminar flow control. This interaction is studied in the context of fully developed flows in curved channels. A part form technical differences associated with boundary layer growth the structures of the instabilities in this flow are very similar to those in the practically more important external boundary layer situation. The interaction is shown to have two distinct phases depending on the size of the disturbances. At very low amplitudes two oblique Tollmein-Schlichting waves interact with a Goertler vortex in such a manner that the amplitudes become infinite at a finite time. This type of interaction is described by ordinary differential amplitude equations with quadratic nonlinearities.
Hall, P.↗
Topical: Boiling, Condensation and Two-Phase Flows in Microgravity
The white paper addresses both fundamental and technological questions in the science of phase-change fluid flows aimed at understanding thermal transport in flow boiling and condensation and the use of these processes in space and terrestrial thermal systems. While flow boiling and condensation are widely employed in Earth-based thermal equipment to reduce the cost, size, and power required to transfer heat, a lack of data and predictive models on the impact of gravity on these phenomena hinders the use of two-phase heat transport in a low-gravity environment. The white paper presents research tasks in long-duration microgravity recommended to expand our knowledge on phase-changing flows. Due to elimination of the masking gravity effects, the proposed research will provide a unique opportunity to bring new insights into the role of capillary and hydrodynamic forces in phase-changing flows. The potential impact of the proposed research ranges from the space power, thermal and cryogenic systems to various terrestrial applications in the petrochemical, pharmaceutical, biochemical, nuclear, and metallurgical industries.
Phase-change fluid flow↗
Turbulent two-phase flow in annular seals
Steady, turbulent two-phase fluid flow in a rotating annular seal with no eccentricity is analyzed. The fluid is assumed to be a homogeneous mixture of liquid and vapor in thermodynamic equilibrum. Further, the flow is assumed to be adiabatic, but the effects due to heat generation by viscous dissipation are accounted for fully. Solution of the model governing differential equations is accomplished by use of a fourth-order Runge-Kutta numerical integration scheme. The calculation of mass leakage rates under choked and unchoked conditions are discussed and the phenomenon of all-liquid choked flow is explained. Several numerical examples are presented supposing cyrogenic oxygen as the sealed fluid.
Beatty, P. A.↗
Numerical and Experimental Studies of the Natural Convection Flow Within a Horizontal Cylinder Subjected to a Uniformly Cold Wall Boundary Condition
Numberical solutions are obtained for the quasi-compressible Navier-Stokes equations governing the time dependent natural convection flow within a horizontal cylinder. The early time flow development and wall heat transfer is obtained after imposing a uniformly cold wall boundary condition on the cylinder. Solutions are also obtained for the case of a time varying cold wall boundary condition. Windware explicit differ-encing is used for the numerical solutions. The viscous truncation error associated with this scheme is controlled so that first order accuracy is maintained in time and space. The results encompass a range of Grashof numbers from 8.34 times 10,000 to 7 times 10 to the 7th power which is within the laminar flow regime for gravitationally driven fluid flows. Experiments within a small scale instrumented horizontal cylinder revealed the time development of the temperature distribution across the boundary layer and also the decay of wall heat transfer with time.
Stewart, R. B.↗
Grid generation for turbomachinery problems
The development of a computer code to generate numerical grids for complex internal flow systems such as the fluid flow inside the space shuttle main engine is outlined. The blending technique for generating a grid for stator-rotor combination at a particular radial section is examined. The computer programs which generate these grids are listed in the Appendices. These codes are capable of generating grids at different cross sections and thus providng three dimensional stator-rotor grids for the turbomachinery of the space shuttle main engine.
Steinhoff, J.↗
Numerical model of solar dynamic radiator for parametric analysis
Growth power requirements for Space Station Freedom will be met through addition of 25 kW solar dynamic (SD) power modules. The SD module rejects waste heat from the power conversion cycle to space through a pumped-loop, multi-panel, deployable radiator. The baseline radiator configuration was defined during the Space Station conceptual design phase and is a function of the state point and heat rejection requirements of the power conversion unit. Requirements determined by the overall station design such as mass, system redundancy, micrometeoroid and space debris impact survivability, launch packaging, costs, and thermal and structural interaction with other station components have also been design drivers for the radiator configuration. Extensive thermal and power cycle modeling capabilities have been developed which are powerful tools in Station design and analysis, but which prove cumbersome and costly for simple component preliminary design studies. In order to aid in refining the SD radiator to the mature design stage, a simple and flexible numerical model was developed. The model simulates heat transfer and fluid flow performance of the radiator and calculates area mass and impact survivability for many combinations of flow tube and panel configurations, fluid and material properties, and environmental and cycle variations. A brief description and discussion of the numerical model, it's capabilities and limitations, and results of the parametric studies performed is presented.
Rhatigan, Jennifer L.↗
Numerical model of solar dynamic radiator for parametric analysis
Growth power requirements for Space Station Freedom will be met through addition of 25 kW solar dynamic (SD) power modules. Extensive thermal and power cycle modeling capabilities have been developed which are powerful tools in Station design and analysis, but which prove cumbersome and costly for simple component preliminary design studies. In order to aid in refining the SD radiator to the mature design stage, a simple and flexible numerical model was developed. The model simulates heat transfer and fluid flow performance of the radiator and calculates area mass and impact survivability for many combinations of flow tube and panel configurations, fluid and material properties, and environmental and cycle variations.
Rhatigan, Jennifer L.↗
Stall-Departure-Resistance Enhancer
Stall-departure-resistance enhancer imposes lesser drag penalty than nortex generators of older types. Increases lift by as much as 30 percent at angles of attack otherwise in poststall region. Device is flat plate wedge with 60 degree sweep angle and attached so it protrudes from leading edge of wing. Tip is sharp point, and edges made thin and sharp to induce good vortical flow. Applications include those intended to increase safety for broad range of aircraft, including trainers, fighters, general-aviation aircraft, and commercial transport aircraft. Nonaerospace applications where flow stall is problem under certain conditions, such as in control of separation in flow diffusers. Other applications in fluid machinery and fluid flow.
Ross, Holly M.↗
A laser fluorescence anemometer system for the Langley 16- by 24-inch water tunnel
A laser fluorescence anemometer which comprises a three-component laser Doppler velocimeter system with a fourth channel to measure fluorescent dye concentration has been installed in the NASA Langley 16- by 24-in water tunnel. The system includes custom designed optics, data acquisition, and traverse control instruments and a custom software package. Feasibility studies demonstrated how water tunnels can be used in conjunction with advanced optical techniques to provide nonintrusive detailed flow field measurements of complex fluid flows with a minimum of expense. The measurements show that the laser fluorescence anemometer can provide new insight into the structure, entrainment, control and of mixing vortical and shear layer flows.
Owen, F. K.↗
Natural Rolling Responses of a Delta Wing in Transonic and Subsonic Flows
The unsteady, three-dimensional, full Navier-Stokes (NS) equations and the Euler equations of rigid-body dynamics are sequentially solved to simulate the natural rolling response of slender delta wings of zero thickness at moderate to high angles of attack, to transonic and subsonic flows. The governing equations of fluid flow and dynamics of the present multi-disciplinary problem are solved using the time-accurate solution of the NS equations with the implicit, upwind, Roe flux-difference splitting, finite-volume scheme and a four-stage Runge-Kutta scheme, respectively. The main focus is to analyze the effect of Mach number and angle of attack on the leading edge vortices and their breakdown, the resultant rolling motion, and overall aerodynamic response of the wing. Three cases demonstrate the natural response of a 65 deg swept, cropped delta wing in a transonic flow with breakdown of the leading edge vortices and an 80 deg swept delta wing in a subsonic flow undergoing either damped or self-excited limit-cycle rolling oscillations as a function of angle of attack. Comparisons with an experimental investigation completes this study, validating the analysis and illustrating the complex details afforded by computational investigations.
Menzies, Margaret A.↗
Investigation of the Crystal Growth of Dielectric Materials by the Bridgman Technique Using Vibrational Control
The principal goal of this ground-based program, which started on February 1, 1998 and concluded on April 30, 2002, was to investigate the influence of low frequency vibrations on the fluid flow and quality of dielectric oxide crystals grown by the vertical Bridgman method. This experimental program was a collaborative effort between Stanford University and the General Physics Institute of the Russian Academy of Sciences in Moscow, and included a strong emphasis on both physical modeling and the growth of some technologically important materials. Additionally it was carried out initially in collaboration with the theoretical and numerical investigations of A.Fedoseyev and I.Alexander (ongoing in another NASA sponsored program). This latter program involved a study of vibro-convective buoyancy-driven flows in cylindrical configurations with the expectation of being able to use vibrational flows to control buoyancy driven fluid transport to off-set the effect of "g-jitter" during microgravity Bridgman crystal growth. These two programs taken together, were designed to lead to a new parametric control variable which can be used to either suppress or control convection, and thereby heat and mass transport during Bridgman crystal growth. It was expected to be effective in either a terrestrial or space environment.
Feigelson, Robert S.↗
The process of separation in the turbulent friction layer
The separation of the flow which occurs at large angles of attack on the suction side of an airplane wing is attributable to phenomena in the flowing fluid layer adjacent to the surface; the fluid particles slowed up by the friction on the surface can no longer advance against an unduly great pressure rise. It is of vital importance that there exist two types of flow - laminar and turbulent - in the fluid layer flowing in the immediate vicinity of a body. According to Prandtl, by whom the whole theory was developed, we speak in the first case of a laminar boundary layer, in the second, of a turbulent friction layer. (author)
Gruschwitz, E↗