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At least 685 records · Page 38

All sources NASA NTRS DOE OSTI

NASA NTRS1979

Test problems for inviscid transonic flow

Solving of test problems with the TRANDES program is discussed. This method utilizes the full, inviscid, perturbation potential flow equation in a Cartesian grid system that is stretched to infinity. This equation is represented by a nonconservative system of finite difference equations that includes at supersonic points a rotated difference scheme and is solved by column relaxation. The solution usually starts from a zero perturbation potential on a very coarse grid (typically 13 by 7) followed by several grid halvings until a final solution is obtained on a fine grid (97 by 49).

Carlson, L. A.↗

NASA NTRS2010

Design and Implementation of a Characterization Test Rig for Evaluating High Bandwidth Liquid Fuel Flow Modulators

A test rig was designed and developed at the NASA Glenn Research Center (GRC) for the purpose of characterizing high bandwidth liquid fuel flow modulator candidates to determine their suitability for combustion instability control research. The test rig is capable of testing flow modulators at up to 600 psia supply pressure and flows of up to 2 gpm. The rig is designed to provide a quiescent flow into the test section in order to isolate the dynamic flow modulations produced by the test article. Both the fuel injector orifice downstream of the test article and the combustor are emulated. The effect of fuel delivery line lengths on modulator dynamic performance can be observed and modified to replicate actual fuel delivery systems. For simplicity, water is currently used as the working fluid, although future plans are to use jet fuel. The rig is instrumented for dynamic pressures and flows and a high-speed data system is used for dynamic data acquisition. Preliminary results have been obtained for one candidate flow modulator.

Saus, Joseph R.↗

NASA NTRS2020

Effect of Atmospheric Wind and Upstream Buildings on the Flow Quality in the Test Section of the 80-by 120-Foot Wind Tunnel

The effect of upwind buildings on flow quality in the test section of the 80- by-120-Foot Wind Tunnel housed at the National Full-Scale Aerodynamics Complex at NASA Ames Research Center was modeled at reduced scale. A 1/50th-scale model of the 80x120 leg was placed on the turntable in the test section of the full-scale NFAC 80x120 wind tunnel. Ambient wind was simulated by means of a fixed linear array of 6 blowers mounted upstream of the NFAC turntable. NFAC turntable rotation was used to change ambient (atmospheric) wind direction. Models of existing upwind buildings and the planned Google Campus buildings (Googleplex) were constructed at 1/50th-scale. In addition, a variety of upwind blockage conditions were studied, using rectangular bodies, to simulate either a 2D or 3D blockage directly ahead of the inlet. Computer-controlled surveys of test section flow quality were measured using a Cobra probe to provide all three orthogonal velocity components. Surprisingly, measurements indicate that test section flow quality will be unaffected or slightly improved by the upwind presence of the Google Campus. A possible explanation is discussed.

open-circuit wind tunnel↗

DOE OSTI2013

Systematic study of polycrystalline flow during tension test of sheet 304 austenitic stainless steel at room temperature

By systematic study the mapping of polycrystalline flow of sheet 304 austenitic stainless steel (ASS) during tension test at constant crosshead velocity at room temperature was obtained. The main results establish that the trajectory of crystals in the polycrystalline spatially extended system (PCSES), during irreversible deformation process obey a hyperbolic motion. Where, the ratio between the expansion velocity of the field and the velocity of the field source is not constant and the field lines of such trajectory of crystals become curved, this accelerated motion is called a hyperbolic motion. Such behavior is assisted by dislocations dynamics and self-accommodation process between crystals in the PCSES. Furthermore, by applying the quantum mechanics and relativistic model proposed by Muñoz-Andrade, the activation energy for polycrystalline flow during the tension test of 304 ASS was calculated for each instant in a global form. In conclusion was established that the mapping of the polycrystalline flow is fundamental to describe in an integral way the phenomenology and mechanics of irreversible deformation processes.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Preliminary Collab Fracture Characterization Results from Flow and Tracer Testing Efforts

The EGS Collab project is developing ~10-20 m-scale field sites where fracture stimulation and flow models can be validated against controlled, small-scale, in-situ experiments. The first multi-well experimental site was established at the 4850 level in the Homestake Mine, where hydraulic fractures were created at an injection well drilled sub-horizontal from the drift. Ten tracer tests were conducted to characterize fracture flow pathways during the second hydraulic characterization test for 164’ Notch (October 24th to November 14th, 2018) during steady state injection of 400 ml/min at the injection well. Injected tracers include DNA, C-dots (fluorescein nano particles), fluorescein, rhodamine-b, sodium chloride, lithium bromide and cesium iodine. The tracers have been detected in three flowing wells located about 7.5 to 9 meters away from the injection interval. The tracer breakthrough curves from these locations have been adjusted to account for the residence time in the injection and production tubing. At the time of writing this paper, only the fluorescent C-dots, rhodamine-b and chloride have been analyzed for concentration vs time/volume at the production wells. Results from early testing have been re-analyzed as to the; amount and location of injected water recovery and the mass of tracer recovered.

15 GEOTHERMAL ENERGY↗

NASA NTRS1992

Tests Of Shear-Flow Model For Acoustic Impedance

Tests described in report conducted to validate two-dimensional shear-flow analytical model for determination of acoustic impedance of acoustic liner in grazing-incidence, grazing-flow environment by use of infinite-waveguide method. Tests successful for both upstream and downstream propagations. Work has potential for utility in testing of engine ducts in commercial aircraft.

Parrot, Tony L.↗

NASA NTRS1971

Dynamic and static wind tunnel tests of a flow direction vane

Low-inertia flow-direction vane static and dynamic wind tunnel tests at subsonic and supersonic speeds for in-flight measurement of bust velocities

Richardson, N. R.↗

NASA NTRS1992

Ultra high bypass Nacelle aerodynamics inlet flow-through high angle of attack distortion test

A flow-through inlet test program was conducted to evaluate inlet test methods and determine the impact of the fan on inlet separation when operating at large angles of attack. A total of 16 model configurations of approximately 1/6 scale were tested. A comparison of these flow-through results with powered data indicates the presence of the fan increased separation operation 3 degrees to 4 degrees over the flow through inlet. Rods and screens located at the fan face station, that redistribute the flow, achieved simulation of the powered-fan results for separation angle of attack. Concepts to reduce inlet distortion and increase angle of attack capability were also evaluated. Vortex generators located on the inlet surface increased inlet angle of attack capability up to 2 degrees and reduced inlet distortion in the separated region. Finally, a method of simulating the fan/inlet aerodynamic interaction using blockage sizing method has been defined. With this method, a static blockage device used with a flow-through model will approximate the same inlet onset of separation angle of attack and distortion pattern that would be obtained with an inlet model containing a powered fan.

Larkin, Michael J.↗

NASA NTRS2020

Development of a Flow Field for Testing a Boundary-Layer-Ingesting Propulsor

In order to test embedded-propulsor technology, modifications were required of the 8x6 Supersonic Wind tunnel at NASA Glenn Research Center. The extent of the modifications required that a new tunnel calibration be completed to generate a new calibration dataset and operational procedures for the tunnel, as well as to map the boundary layer on the raised floor. This report describes the propulsor inflow that was to be simulated, documents the tunnel modifications that were required, and conveys the results of the calibration test that was completed to measure the resulting flow properties.

boundary layer↗

NASA NTRS1987

Flow energizer flight tests on a light twin aircraft

Experiments were conducted to explore the use of flow energizers (i.e., horizontally mounted vortex generators), using a special instrumentation subsystem installed on a light twin aircraft. The data, collected for energizer configurations with convergence ratios of 1.2, 1.5, and 1.7, included measurements of pressure on the wing surface, velocity components in the wake of the energizer, and forces on the flow energizer itself. Surface pressure data showed that flow energizer effects are highly localized. The energizer with the smallest convergence ratio tested produced an energizer lift/drag ratio about 75 percent lower that that of the other two configurations. For highly swept planforms, cambered energizers with overlaps of the order of 12-15 percent of the local chord provide the best results.

Ward, D. T.↗

DOE OSTI2016

Scaling and Design Analysis of a Sub-Scale, Reduced Temperature Stratified Flow Separate Effects Test Facility for the Experimental Investigation of Air Ingress in a High Temperature Reactor System

High temperature gas reactors (HTGR) are poised to spearhead the next generation of nuclear reactors, due to their passive safety characteristics and their applications flexibility. Able to provide base load power or process heat for industrial applications, HGTRs may be a critical component to reducing greenhouse gas emissions in the United States and abroad. However, increased interest and development has also highlighted areas requiring further investigation, one of which being the air-ingress accident. Air ingress may occur following a break in the coaxial cross duct and pressure vessel depressurization. The initial mode of ingress is hypothesized to be density driven cross flow as the cold air enters the lower plenum, at which point molecular diffusion and/or local buoyancy phenomena will dominate until a global natural circulation current is established. While computational simulations support this progression, little or no experimental data exists to validate and support this phenomenology. Therefore, it is necessary to generate such data; this research seeks to do so through the use of a sub-scale separate effects test facility - the Stratified Flow Separate Effects Test Facility (SFSETF). The goal of this facility is more specifically to focus on the transition to global natural circulation starting from air ingress after a double-ended guillotine break (DEGB) while neglecting depressurization. This paper will provide analyses performed in the design of this facility, including the geometric and hydraulic scaling analyses, safety analysis and instrumentation selection. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

NASA NTRS1990

The Mach number of the cosmic flow - A critical test for current theories

A new cosmological, self-contained test using the ratio of mean velocity and the velocity dispersion in the mean flow frame of a group of test objects is presented. To allow comparison with linear theory, the velocity field must first be smoothed on a suitable scale. In the context of linear perturbation theory, the Mach number M(R) which measures the ratio of power on scales larger than to scales smaller than the patch size R, is independent of the perturbation amplitude and also of bias. An apparent inconsistency is found for standard values of power-law index n = 1 and cosmological density parameter Omega = 1, when comparing values of M(R) predicted by popular models with tentative available observations. Nonstandard models based on adiabatic perturbations with either negative n or small Omega value also fail, due to creation of unacceptably large microwave background fluctuations.

Ostriker, Jeremiah P.↗

DOE OSTI2018

Resistively Heated Target Tests Using Helium Flow Loop

A helium flow and heat transfer experiment has been conducted using the helium flow loop facility at the Los Alamos National Laboratory. In order to replicate the helium cooled Mo-100 plant design disks during beam heating, an array of resistive heaters were placed within the helium flow loop, and cooled via helium. The resistively heated test piece is comprised of seven ceramic electric heaters with embedded thermocouples allowing temperature measurements of each heater.Computation fluid dynamic (CFD) simulations and analysis from theory are compared to the experiment results in order to have predictable capabilities for future experiments.

42 ENGINEERING↗

NASA NTRS1973

Apparatus and method for generating large mass flow of high temperature air at hypersonic speeds

High temperature, high mass air flow and a high Reynolds number test air flow in the Mach number 8-10 regime of adequate test flow duration is attained by pressurizing a ceramic-lined storage tank with air to a pressure of about 100 to 200 atmospheres. The air is heated to temperatures of 7,000 to 8,000 R prior to introduction into the tank by passing the air over an electric arc heater means. The air cools to 5,500 to 6,000 R while in the tank. A decomposable gas such as nitrous oxide or a combustible gas such as propane is injected into the tank after pressurization and the heated pressurized air in the tank is rapidly released through a Mach number 8-10 nozzle. The injected gas medium upon contact with the heated pressurized air effects an exothermic reaction which maintains the pressure and temperature of the pressurized air during the rapid release.

Sabol, A. P.↗

DOE OSTI2018

High Air-Flow Aerosol Filtration Testing

Pressure losses and aerosol collection efficiencies were measured for fibrous filter materials at air-flow rates consistent with high efficiency filtration (hundreds of cubic feet per minute). Microfiber filters coated with nanofibers were purchased and fabricated into test assemblies for a 12-inch duct system designed to mimic high efficiency filtration testing of commercial and industrial processes. Standards and specifications for high efficiency filtration were studied from a variety of institutions to assess protocols for design, testing, operations and maintenance, and quality assurance (e.g., DOE, ASHRAE, ASME). Three materials with varying Minimum Efficiency Reporting Values (MERV) were challenged with sodium chloride aerosol. Substantial filter loading was observed where aerosol collection efficiencies and pressure losses increased during experiments. Filter designs will be optimized and characterized in subsequent years of this study. Additional testing will be performed with higher hazard aerosols at Oak Ridge National Laboratory.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

NASA NTRS1983

A flight test of laminar flow control leading-edge systems

NASA's program for development of a laminar flow technology base for application to commercial transports has made significant progress since its inception in 1976. Current efforts are focused on development of practical reliable systems for the leading-edge region where the most difficult problems in applying laminar flow exist. Practical solutions to these problems will remove many concerns about the ultimate practicality of laminar flow. To address these issues, two contractors performed studies, conducted development tests, and designed and fabricated fully functional leading-edge test articles for installation on the NASA JetStar aircraft. Systems evaluation and performance testing will be conducted to thoroughly evaluate all system capabilities and characteristics. A simulated airline service flight test program will be performed to obtain the operational sensitivity, maintenance, and reliability data needed to establish that practical solutions exist for the difficult leading-edge area of a future commercial transport employing laminar flow control.

Fischer, M. C.↗

NASA NTRS1983

A flight test of laminar flow control leading-edge systems

Fischer, M. C.↗

NASA NTRS2014

Flight Tests of a Supersonic Natural Laminar Flow Airfoil

A flight test campaign of a supersonic natural laminar flow airfoil has been recently completed. The test surface was an 80-inch (203 cm) chord and 40-inch (102 cm) span article mounted on the centerline store location of an F-15B airplane. The wing was designed with a leading edge sweep of effectively 0 deg to minimize boundary layer crossflow. The test article surface was coated with an insulating material to avoid significant heat transfer to and from the test article structure to maintain a quasi-adiabatic wall. An aircraft-mounted infrared camera system was used to determine boundary layer transition and the extent of laminar flow. The tests were flown up to Mach 2.0 and chord Reynolds numbers in excess of 30 million. The objectives of the tests were to determine the extent of laminar flow at high Reynolds numbers and to determine the sensitivity of the flow to disturbances. Both discrete (trip dots) and 2-D disturbances (forward-facing steps) were tested. A series of oblique shocks, of yet unknown origin, appeared on the surface, which generated sufficient crossflow to affect transition. Despite the unwanted crossflow, the airfoil performed well. The results indicate the sensitivity of the flow to the disturbances, which can translate into manufacturing tolerances, were similar to that of subsonic natural laminar flow wings.

Frederick, M. A.↗