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At least 397 records · Page 22

Manual of Scaling Methods

This manual reviews the derivation of the similitude relationships believed to be important to ice accretion and examines ice-accretion data to evaluate their importance. Both size scaling and test-condition scaling methods employing the resulting similarity parameters are described, and experimental icing tests performed to evaluate scaling methods are reviewed with results. The material included applies primarily to unprotected, unswept geometries, but some discussion of how to approach other situations is included as well. The studies given here and scaling methods considered are applicable only to Appendix-C icing conditions. Nearly all of the experimental results presented have been obtained in sea-level tunnels. Recommendations are given regarding which scaling methods to use for both size scaling and test-condition scaling, and icing test results are described to support those recommendations. Facility limitations and size-scaling restrictions are discussed. Finally, appendices summarize the air, water and ice properties used in NASA scaling studies, give expressions for each of the similarity parameters used and provide sample calculations for the size-scaling and test-condition scaling methods advocated.

Bond, Thomas H.↗

Design, analysis, and testing of a metal matrix composite web/flange intersection

An experimental and analytical program to study the local design details of a typical T-shaped web/flange intersection made from a metal matrix composite is described. Loads creating flange bending were applied to specimens having different designs and boundary conditions. Finite element analyses were conducted on models of the test specimens to predict the structural response. The analyses correctly predict failure load, mode, and location in the fillet material in the intersection region of the web and the flange when specimen quality is good. The test program shows the importance of fabrication quality in the intersection region. The full-scale test program that led to the investigation of this local detail is also described.

Biggers, S. B.↗

The Ability of AMSTAR Dechlorination Solution to Remove and Degrade PCBs from Contaminated Surfaces

Polychlorinated biphenyls (PCBs) are a group of synthetic aromatic compounds with the general formula C12H(10-x)Cl(-x) that were historically used in industrial paints, caulking material and adhesives, as their properties enhanced structural integrity, reduced flammability and boosted antifungal properties. Although the United States Environmental Protection Agency (USEPA) has banned the manufacture of PCBs since 1979, they have been found in at least 500 of the 1,598 National Priorities List (Superfund) sites identified by the USEPA. Prior to the US EPA's ban on PCB production, PCBs were commonly used as additives in paints and asphalt-based adhesives that were subsequently applied to a variety of structures. Government facilities constructed as early as 1930 utilized PCB-containing binders or PCB-containing paints, which are now leaching into the environment and posing ecological and worker health concerns. In 2006, a commercially available product known as AMSTAR Dechlorination Solution was tested at NASA's Kennedy Space Center for its ability to remove and degrade PCBs from structural materials. This evaluation was requested by the Environmental Security Technology Certification Program (ESTCP) evaluating the ability of NASA's Bimetallic Treatment System (BTS) to remove and degrade PCBs from structural materials. The results of the laboratory testing are to be used to determine if a side-by-side field-scale test comparing BTS to AMSTAR was warranted. A recommended sampling and analysis testing program was submitted to ESTCP that included triplicate screening of AMSTAR's PCB dechlorination capabilities on a variety of surfaces including glass, bare metal, and painted metal coupons. The test procedures, analytical techniques and results obtained are presented in this interim report to ESTCP.

Quinn, Jacqueline E.↗

A status report on NASA general aviation stall/spin flight testing

The NASA Langley Research Center has undertaken a comprehensive program involving spin tunnel, static and rotary balance wind tunnel, full-scale wind tunnel, free flight radio control model, flight simulation, and full-scale testing. Work underway includes aerodynamic definition of various configurations at high angles of attack, testing of stall and spin prevention concepts, definition of spin and spin recovery characteristics, and development of test techniques and emergency spin recovery systems. This paper presents some interesting results to date for the first aircraft (low-wing, single-engine) in the program, in the areas of tail design, wing leading edge design, mass distribution, center of gravity location, and small airframe changes, with associated pilot observations. The design philosophy of the spin recovery parachute system is discussed in addition to test techniques.

Patton, J. M., Jr.↗

A Summary of Results from Vertical Drop Testing of Hybrid III and WIAMan ATDs

With the development and maturation of the Urban Air Mobility (UAM) market, many new types of electric vertical take-off and landing (eVTOL) vehicles will be flying in the national airspace carrying goods, people or conducting operations for a variety of missions. These types of vehicles are unlike current aircraft due to their novel design and operational profile. Several considerations must be examined in areas including noise, comfort and safety in order for these vehicles to be utilized and accepted into the current airspace system. Researchers at NASA Langley Research Center (LaRC) have conducted sub-scale and full-scale tests on representative eVTOL airframes and seats under a variety of dynamic impact conditions. These tests were conducted to generate data necessary to inform the development of standards in the areas specific to crashworthiness of eVTOL vehicle systems and safety. The data in this report relates to occupant responses obtained during a test campaign utilizing various makes, models, and sizes of Anthropomorphic Test Devices (ATD’s, a.k.a. crash test dummies) undergoing vertical impacts in a variety of seats. The data is intended to provide occupant behavior response and injury metrics for several anticipated impact scenarios that may occur in eVTOL operations. This report will present test data highlighting the effects of several variables on the test results. Discussions on the ATD sizes, along with comparisons between different ATD makes and types will be included. The performance of an in-house developed energy absorbing seat will be detailed, and discussions pertaining to the applicability in various loading conditions will be presented. Finally, a discussion as to the applicability of the tested results to eVTOL full-scale conditions will be included.

Dynamic Drop Testing↗

Planning for Plume Diagnostics for Ground Testing of J-2X Engines at the SSC

John C. Stennis Space Center (SSC) is the premier test facility for liquid rocket engine development and certification for the National Aeronautics and Space Administration (NASA). Therefore, it is no surprise that the SSC will play the most prominent role in the engine development testing and certification for the J-2X engine. The Pratt & Whitney Rocketdyne J-2X engine has been selected by the Constellation Program to power the Ares I Upper Stage Element and the Ares V Earth Departure Stage in NASA s strategy of risk mitigation for hardware development by building on the Apollo program and other lessons learned to deliver a human-rated engine that is on an aggressive development schedule, with first demonstration flight in 2010 and human test flights in 2012. Accordingly, J-2X engine design, development, test, and evaluation is to build upon heritage hardware and apply valuable experience gained from past development and testing efforts. In order to leverage SSC s successful and innovative expertise in the plume diagnostics for the space shuttle main engine (SSME) health monitoring,1-10 this paper will present a blueprint for plume diagnostics for various proposed ground testing activities for J-2X at SSC. Complete description of the SSC s test facilities, supporting infrastructure, and test facilities is available in Ref. 11. The A-1 Test Stand is currently being prepared for testing the J-2X engine at sea level conditions. The A-2 Test Stand is currently being used for testing the SSME and may also be used for testing the J-2X engine at sea level conditions in the future. Very recently, ground-breaking ceremony for the new A-3 rocket engine test stand took place at SSC on August 23, 2007. A-3 is the first large - scale test stand to be built at the SSC since the A and B stands were constructed in the 1960s. The A-3 Test Stand will be used for testing J-2X engines under vacuum conditions simulating high altitude operation at approximately 30,480 m (100,000 ft). To achieve the simulated altitude environment, chemical steam generators using isopropyl alcohol, LOX, and RELEASED - Printed documents may be obsolete; validate prior to use. water would run for the duration of the test and would generate approximately 2096 Kg/s of steam to reduce pressure in the test cell and downstream of the engine. The testing at the A-3 Test Stand is projected to begin in late 2010, meanwhile the J-2X component testing on A-1 is scheduled to begin later this year.

SaintCyr, William W.↗

AMC EN-1038: Reduced scale solar simulator supplementary test report

The reduced scale solar simulator program conducted by the Advanced Manufacturing Center at Cleveland State University in 1992 provided sufficient data to support the selection of the uniform magnification solar simulator module for the Solar Dynamic Ground Test Demonstrator Program (SDGTD) at NASA LeRC. In 1993, additional testing of the reduced scale solar simulator was conducted to provide information to refine and improve the design of the full scale solar simulator. This report presents the results of these additional tests.

Biering, Robert C.↗

Study and design of cryogenic propellant acquisition systems. Volume 2: Supporting experimental program

Areas of cryogenic fuel systems were identified where critical experimental information was needed either to define a design criteria or to establish the feasibility of a design concept or a critical aspect of a particular design. Such data requirements fell into three broad categories: (1) basic surface tension screen characteristics; (2) screen acquisition device fabrication problems; and (3) screen surface tension device operational failure modes. To explore these problems and to establish design criteria where possible, extensive laboratory or bench test scale experiments were conducted. In general, these proved to be quite successful and, in many instances, the test results were directly used in the system design analyses and development. In some cases, particularly those relating to operational-type problems, areas requiring future research were identified, especially screen heat transfer and vibrational effects.

Burge, G. W.↗

Progress on Variable Cycle Engines

Progress in the development and future requirements of the Variable Stream Control Engine (VSCE) are presented. The two most critical components of this advanced system for future supersonic transports, the high performance duct burner for thrust augmentation, and the low jet coannular nozzle were studied. Nozzle model tests substantiated the jet noise benefit associated with the unique velocity profile possible with a coannular nozzle system on a VSCE. Additional nozzle model performance tests have established high thrust efficiency levels only at takeoff and supersonic cruise for this nozzle system. An experimental program involving both isolated component and complete engine tests has been conducted for the high performance, low emissions duct burner with good results and large scale testing of these two components is being conducted using a F100 engine as the testbed for simulating the VSCE. Future work includes application of computer programs for supersonic flow fields to coannular nozzle geometries, further experimental testing with the duct burner segment rig, and the use of the Variable Cycle Engine (VCE) Testbed Program for evaluating the VSCE duct burner and coannular nozzle technologies.

Westmoreland, J. S.↗

Progress with variable cycle engines

The evaluation of components of an advanced propulsion system for a future supersonic cruise vehicle is discussed. These components, a high performance duct burner for thrust augmentation and a low jet noise coannular exhaust nozzle, are part of the variable stream control engine. An experimental test program involving both isolated component and complete engine tests was conducted for the high performance, low emissions duct burner with excellent results. Nozzle model tests were completed which substantiate the inherent jet noise benefit associated with the unique velocity profile possible of a coannular exhaust nozzle system on a variable stream control engine. Additional nozzle model performance tests have established high thrust efficiency levels at takeoff and supersonic cruise for this nozzle system. Large scale testing of these two critical components is conducted using an F100 engine as the testbed for simulating the variable stream control engine.

Westmoreland, J. S.↗

Liquid Motion in a Rotating Tank Experiment (LME)

The Liquid Motion in Rotating Tank Experiment (LME) will investigate and quantify liquid motions occurring in spin-stabilized spacecraft; acquire representative data to validate ground-test scaling procedures; and obtain scientific understanding to formulate better analytical models. LME eliminates the limitations of ground testing. LME design is nearing the end of phase B: the breadboard hardware model has been completed; the load cells have been fabricated and tested; the experiment computer has been flight qualified; and other electronics have been breadboarded. Various aspects of this experiment are presented in viewgraph form.

Dodge, F. T.↗

Low Cost Nuclear Thermal Rocket Cermet Fuel Element Environment Testing

Deep space missions with large payloads require high specific impulse (Isp) and relatively high thrust in order to achieve mission goals in reasonable time frames. Conventional, storable propellants produce average Isp. Nuclear thermal rockets (NTR) capable of high Isp thrust have been proposed. NTR employs heat produced by fission reaction to heat and therefore accelerate hydrogen which is then forced through a rocket nozzle providing thrust. Fuel element temperatures are very high (up to 3000K) and hydrogen is highly reactive with most materials at high temperatures. Data covering the effects of high temperature hydrogen exposure on fuel elements is limited. The primary concern is the mechanical failure of fuel elements which employ high-melting-point metals, ceramics or a combination (cermet) as a structural matrix into which the nuclear fuel is distributed. It is not necessary to include fissile material in test samples intended to explore high temperature hydrogen exposure of the structural support matrices. A small-scale test bed designed to heat fuel element samples via non-contact RF heating and expose samples to hydrogen is being developed to assist in optimal material and manufacturing process selection without employing fissile material. This paper details the test bed design and results of testing conducted to date.

Bradley, David E.↗

Phytoremediation of Indoor Air: NASA, Bill Wolverton, and the Development of an Industry

It was during this period of the early 1970's and 1980's when the issues associated with Sick Building Syndrome were gaining attention that the United States National Aeronautics and Space Administration (NASA) became an unlikely leader in identifying biological solutions to the problem of poor indoor air quality. NASA had been supporting work using biological systems for atmospheric regeneration since the 1950's, with the emphasis on using photosynthetic systems for the removal of carbon dioxide and regeneration of oxygen as part of a life support system. The then Soviet Union was conducting tests using algae systems in the BIO-1 program (1964-1968) to regenerate the air at the Siberian Branch of the Soviet Academy of Sciences in Krasnoyarsk (Later renamed the Institute of Biophysics). These tests were expanded to include the use of higher plants in the BIOS-2 testing in the 1970's, and humans during BIO-3 in the 1980'SI3. Within NASA, large scale testing of bioregenerative life support systems was conducted in the Biomass Production Chamber (BPC) at Kennedy Space Center, Florida as part of the Controlled Ecological Life Support Systems (CELSS) Breadboard project.

Stutte, Gary W.↗

Compact Fuel Element Environment Test

Deep space missions with large payloads require high specific impulse (I(sub sp)) and relatively high thrust to achieve mission goals in reasonable time frames. Conventional, storable propellants produce average I(sub sp). Nuclear thermal rockets (NTRs) capable of high I(sub sp) thrust have been proposed. NTR employs heat produced by fission reaction to heat and therefore accelerate hydrogen, which is then forced through a rocket nozzle providing thrust. Fuel element temperatures are very high (up to 3,000 K) and hydrogen is highly reactive with most materials at high temperatures. Data covering the effects of high-temperature hydrogen exposure on fuel elements are limited. The primary concern is the mechanical failure of fuel elements that employ high melting point metals, ceramics, or a combination (cermet) as a structural matrix into which the nuclear fuel is distributed. It is not necessary to include fissile material in test samples intended to explore high-temperature hydrogen exposure of the structural support matrices. A small-scale test bed designed to heat fuel element samples via noncontact radio frequency heating and expose samples to hydrogen for typical mission durations has been developed to assist in optimal material and manufacturing process selection without employing fissile material. This Technical Memorandum details the test bed design and results of testing conducted to date.

Bradley, D. E.↗

Next Generation Active Buffet Suppression System

Buffeting is an aeroelastic phenomenon that is common to high performance aircraft, especially those with twin vertical tails like the F/A-18, at high angles of attack. These loads result in significant random stresses, which may cause fatigue damage leading to restricted capabilities and availability of the aircraft. This paper describes an international collaborative research activity among Australia, Canada and the United States involving the use of active structural control to alleviate the damaging structural response to these loads. The research program is being co-ordinated by the Air Force Research Laboratory (AFRL) and is being conducted under the auspices of The Technical Cooperative Program (TTCP). This truly unique collaborative program has been developed to enable each participating country to contribute resources toward a program that coalesces a broad range of technical knowledge and expertise into a single investigation. This collaborative program is directed toward a full-scale test of an F/A-18 empennage, which is an extension of an earlier initial test. The current program aims at applying advanced directional piezoactuators, the aircraft rudder, switch mode amplifiers and advanced control strategies on a full-scale structure to demonstrate the enhanced performance and capability of the advanced active BLA control system in preparation for a flight test demonstration.

Galea, Stephen C.↗

Aging aircraft NDI Development and Demonstration Center (AANC): An overview

A major center with emphasis on validation of nondestructive inspection (NDI) techniques for aging aircraft, the Aging Aircraft NDI Development and Demonstration Center (AANC), has been funded by the FAA at Sandia National Laboratories. The Center has been assigned specific tasks in developing techniques for the nondestructive inspection of static engine parts, assessing inspection reliability (POD experiments), developing testbeds for NDI validation, maintaining a FAA library of characterized aircraft structural test specimens, and leasing a hangar to house a high flight cycle transport aircraft for use as a full scale test bed.

Aging Aircraft↗

Recent Advances in the LEWICE Icing Model

This paper will describe two recent modifications to the Glenn ICE software. First, a capability for modeling ice crystals and mixed phase icing has been modified based on recent experimental data. Modifications have been made to the ice particle bouncing and erosion model. This capability has been added as part of a larger effort to model ice crystal ingestion in aircraft engines. Comparisons have been made to ice crystal ice accretions performed in the NRC Research Altitude Test Facility (RATFac). Second, modifications were made to the run back model based on data and observations from thermal scaling tests performed in the NRC Altitude Icing Tunnel.

fluid dynamics↗