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NASA NTRSDate not supplied

Particle and Trace Gas Emissions Indices Measured During the 2021 Boeing ecoDemonstrator Emissions Ground Test

We present particle and trace gas emissions indices sampled on the ground at 30 meters behind the CFM LEAP-1B engines of the Boeing ecoDemonstrator 737-9 aircraft. Testing was carried out at Boeing Field in Seattle, WA, USA in Fall of 2021. Four different fuels were investigated including a 100% sustainable aviation fuel (SAF), a petroleum-based Jet A fuel, and two SAF blends. Total and non-volatile particle number concentrations were measured with a pair of condensation particle counters with one operating behind a custom-built thermal denuder heated to 350 degrees Celsius. Similarly, total and non-volatile particle number size distributions were measured with a pair of Scanning Mobility Particle Sizers (SMPSs). Non-volatile particle mass was estimated from particle light absorption techniques using an assumed mass absorption coefficient, while particle chemical speciation was measured by an Soot Particle Aerosol Mass Spectrometer (SP-AMS). A detailed list of instruments is given on the project website [1]. Overall, the results are consistent with expectations based on ICAO Emissions Databank certification data for the LEAP-1B with a stark reduction in non-volatile particle number and mass observed for the higher thrust conditions when the combustor was staged. The production of volatile particles under these conditions as well as experimental considerations related to background subtraction methods will be discussed.

Benjamin A. Nault↗
NASA NTRS2014

NASA Rocket Propulsion Test Replacement Effort for Oxygen System Cleaner - Hydrochlorofluorocarbon (HCFC) 225

Gaseous and liquid oxygen are extremely reactive materials used in bipropellant propulsion systems. Both flight and ground oxygen systems require a high level of cleanliness to support engine performance, testing, and prevent mishaps. Solvents used to clean and verify the cleanliness of oxygen systems and supporting test hardware must be compatible with the system's materials of construction and effective at removing or reducing expected contaminants to an acceptable level. This paper will define the philosophy and test approach used for evaluating replacement solvents for the current Marshall Space Flight Center/Stennis Space Center baseline HCFC‐225 material that will no longer be available for purchase after 2014. MSFC/SSC applications in cleaning / sampling oxygen propulsion components, support equipment, and test system were reviewed then candidate replacement cleaners and test methods selected. All of these factors as well as testing results will be discussed.

DeWitt Burns, H.↗
NASA NTRS1993

A function approximation approach to anomaly detection in propulsion system test data

Ground test data from propulsion systems such as the Space Shuttle Main Engine (SSME) can be automatically screened for anomalies by a neural network. The neural network screens data after being trained with nominal data only. Given the values of 14 measurements reflecting external influences on the SSME at a given time, the neural network predicts the expected nominal value of a desired engine parameter at that time. We compared the ability of three different function-approximation techniques to perform this nominal value prediction: a novel neural network architecture based on Gaussian bar basis functions, a conventional back propagation neural network, and linear regression. These three techniques were tested with real data from six SSME ground tests containing two anomalies. The basis function network trained more rapidly than back propagation. It yielded nominal predictions with, a tight enough confidence interval to distinguish anomalous deviations from the nominal fluctuations in an engine parameter. Since the function-approximation approach requires nominal training data only, it is capable of detecting unknown classes of anomalies for which training data is not available.

Whitehead, Bruce A.↗
NASA NTRS2005

Hyper-X Mach 7 Scramjet Design, Ground Test and Flight Results

The successful Mach 7 flight test of the Hyper-X (X-43) research vehicle has provided the major, essential demonstration of the capability of the airframe integrated scramjet engine. This flight was a crucial first step toward realizing the potential for airbreathing hypersonic propulsion for application to space launch vehicles. However, it is not sufficient to have just achieved a successful flight. The more useful knowledge gained from the flight is how well the prediction methods matched the actual test results in order to have confidence that these methods can be applied to the design of other scramjet engines and powered vehicles. The propulsion predictions for the Mach 7 flight test were calculated using the computer code, SRGULL, with input from computational fluid dynamics (CFD) and wind tunnel tests. This paper will discuss the evolution of the Mach 7 Hyper-X engine, ground wind tunnel experiments, propulsion prediction methodology, flight results and validation of design methods.

Ferlemann, Shelly M.↗
NASA NTRS2013

Multi-Partner Experiment to Test Volcanic-Ash Ingestion by a Jet Engine

A research team of U.S. Government agencies and engine manufacturers are designing an experiment to test volcanic-ash ingestion by a NASA owned F117 engine that was donated by the U.S. Air Force. The experiment is being conducted under the auspices of NASA s Vehicle Integrated Propulsion Research (VIPR) Program and will take place in early 2014 at Edwards AFB in California as an on-ground, on-wing test. The primary objectives are to determine the effect on the engine of several hours of exposure to low to moderate ash concentrations, currently proposed at 1 and 10 mg/m3 and to evaluate the capability of engine health management technologies for detecting these effects. A natural volcanic ash will be used that is representative of distal ash clouds many 100's to approximately 1000 km from a volcanic source i.e., the ash should be composed of fresh glassy particles a few tens of microns in size. The glassy ash particles are expected to soften and become less viscous when exposed to the high temperatures of the combustion chamber, then stick to the nozzle guide vanes of the high-pressure turbine. Numerous observations and measurements of the engine s performance and degradation will be made during the course of the experiment, including borescope and tear-down inspections. While not intended to be sufficient for rigorous certification of engine performance when ash is ingested, the experiment should provide useful information to aircraft manufacturers, airline operators, and military and civil regulators in their efforts to evaluate the range of risks that ash hazards pose to aviation.

Lekki, John↗
NASA NTRS1992

Automatic detection of anomalies in Space Shuttle Main Engine turbopumps

A prototype expert system (developed on both PC and Symbolics 3670 lisp machine) for detecting anomalies in turbopump vibration data has been tested with data from ground tests 902-473, 902-501, 902-519, and 904-097 of the Space Shuttle Main Engine (SSME). The expert system has been utilized to analyze vibration data from each of the following SSME components: high-pressure oxidizer turbopump, high-pressure fuel turbopump, low-pressure fuel turbopump, and preburner boost pump. The expert system locates and classifies peaks in the power spectral density of each 0.4-sec window of steady-state data. Peaks representing the fundamental and harmonic frequencies of both shaft rotation and bearing cage rotation are identified by the expert system. Anomalies are then detected on the basis of sequential criteria and two threshold criteria set individually for the amplitude of each of these peaks: a prior threshold used during the first few windows of data in a test, and a posterior threshold used thereafter. In most cases the anomalies detected by the expert system agree with those reported by NASA. The two cases where there is significant disagreement will be further studied and the system design refined accordingly.

Lo, Ching F.↗
NASA NTRS2010

Roles of Engineering Correlations in Hypersonic Entry Boundary Layer Transition Prediction

Efforts to design and operate hypersonic entry vehicles are constrained by many considerations that involve all aspects of an entry vehicle system. One of the more significant physical phenomenon that affect entry trajectory and thermal protection system design is the occurrence of boundary layer transition from a laminar to turbulent state. During the Space Shuttle Return To Flight activity following the loss of Columbia and her crew of seven, NASA's entry aerothermodynamics community implemented an engineering correlation based framework for the prediction of boundary layer transition on the Orbiter. The methodology for this implementation relies upon similar correlation techniques that have been is use for several decades. What makes the Orbiter boundary layer transition correlation implementation unique is that a statistically significant data set was acquired in multiple ground test facilities, flight data exists to assist in establishing a better correlation and the framework was founded upon state of the art chemical nonequilibrium Navier Stokes flow field simulations. Recent entry flight testing performed with the Orbiter Discovery now provides a means to validate this engineering correlation approach to higher confidence. These results only serve to reinforce the essential role that engineering correlations currently exercise in the design and operation of entry vehicles. The framework of information related to the Orbiter empirical boundary layer transition prediction capability will be utilized to establish a fresh perspective on this role, and to discuss the characteristics which are desirable in a next generation advancement. The details of the paper will review the experimental facilities and techniques that were utilized to perform the implementation of the Orbiter RTF BLT Vsn 2 prediction capability. Statistically significant results for multiple engineering correlations from a ground testing campaign will be reviewed in order to describe why only certain correlations were selected for complete implementation to support the Shuttle Program. Historical Orbiter flight data on early boundary layer transition due to protruding gap fillers will be described in relation to the selected empirical correlations. In addition, Orbiter entry flight testing results from the BLT Flight Experiment will be discussed in relation to these correlations. Applicability of such correlations to the entry design problem will be reviewed, and finally a perspective on the desirable characteristics for a next generation capability based on high fidelity physical models will be provided.

Campbell, Charles H.↗
NASA NTRS1980

Analytical investigation of fan tone noise due to ingested atmospheric turbulence

The atmospheric turbulence involved in the fan noise generation is evaluated with an existing model for the atmospheric turbulence and an extended version of an existing model concerned with the effects of a flow contraction on convected turbulence. Fan tone noise due to ingested atmospheric turbulence is evaluated with existing fan noise models. The results indicate that the difference in fan narrowband noise due to atmospheric turbulence between static and flight landing approach conditions is in the order of 30 dB. It is concluded that fan noise due to atmospheric turbulence is insignificant in flight conditions for the fans used in the current high bypass ratio engines. The difference in fan narrowband noise between the two conditions is primarily due to the low intensity of the turbulence involved in fan noise generation in flight conditions. Fan noise due to atmospheric turbulence in static conditions should be reduced below the flight fan broadband noise levels which is best achieved with a reduction in the intensity of the fan inflow turbulence. Such a reduction can be obtained with the use of an inflow control device, low wind velocities, small surface roughness in the test stand environment, and large engine axis height above the ground. Peak sound power levels for fan tone noise due to ingested turbulence occur for transverse integral scales in the order of 25% of the rotor blade spacing in the fan tip region.

Ganz, U. W.↗
NASA NTRS1999

Vacuum Plasma Spray (VPS) Forming of Solar Thermal Propulsion Components Using Refractory Metals

The Thermal Spray Laboratory at NASA's Marshall Space Flight Center has developed and demonstrated a fabrication technique using Vacuum Plasma Spray (VPS) to form structural components from a tungsten/rhenium alloy. The components were assembled into an absorber cavity for a fully-functioning, ground test unit of a solar then-nal propulsion engine. The VPS process deposits refractory metal onto a graphite mandrel of the desired shape. The mandrel acts as a male mold, forming the required contour and dimensions of the inside surface of the deposit. Tungsten and tungsten/25% rhenium were used in the development and production of several absorber cavity components. These materials were selected for their high temperature (greater than 25000 C [greater than 4530 F]) strength. Each absorber cavity comprises 3 coaxial shells with two, double-helical flow passages through which the propellant gas flows. This paper describes the processing techniques, design considerations, and process development associated with forming these engine components.

Zimmerman, Frank R.↗
NASA NTRS2009

A Review of Aerothermal Modeling for Mars Entry Missions

The current status of aerothermal analysis for Mars entry missions is reviewed. The aeroheating environment of all Mars missions to date has been dominated by convective heating. Two primary uncertainties in our ability to predict forebody convective heating are turbulence on a blunt lifting cone and surface catalysis in a predominantly CO2 environment. Future missions, particularly crewed vehicles, will encounter additional heating from shock-layer radiation due to a combination of larger size and faster entry velocity. Localized heating due to penetrations or other singularities on the aeroshell must also be taken into account. The physical models employed to predict these phenomena are reviewed, and key uncertainties or deficiencies inherent in these models are explored. Capabilities of existing ground test facilities to support aeroheating validation are also summarized. Engineering flight data from the Viking and Pathfinder missions, which may be useful for aerothermal model validation, are discussed, and an argument is presented for obtaining additional flight data. Examples are taken from past, present, and future Mars entry missions, including the twin Mars Exploration Rovers and the Mars Science Laboratory, scheduled for launch by NASA in 2011.

Wright, Michael J↗
NASA NTRSDate not supplied

NASA's Innovative Entry Systems and TPS Technologies Enabling Commercial Space Missions

For over six decades, the NASA Ames Entry Systems and Technology Division has been a cornerstone of U.S. space exploration, delivering critical atmospheric entry solutions since Project Mercury and now increasingly supporting the commercial space sector. The Division provides reliable entry system solutions through a unique blend of expertise, national facilities, and systems integration knowledge, a combination that is difficult to replicate outside a dedicated government entity. Consistently successful, the TS Division remains central to NASA’s exploration objectives and significantly contributes to the transfer of technology to the commercial space sector, supporting more than ten commercial space companies and supplying flight heatshields to three of them in the past five years. Its strengths in Thermal Protection System (TPS) materials, aerothermodynamics, ground test facilities, and Entry, Descent, and Landing (EDL) systems engineering drive rapid development and sustained U.S. competitiveness in space. The Division's expertise in reusable and ablative thermal protection systems, as well as mechanically deployable entry systems primarily developed for NASA missions, now benefits commercial space missions. This presentation will highlight the vision and needs of these commercial space companies, how NASA-invented technologies meet mission requirements, and how these technologies enable and distinguish their efforts.

Ethiraj Venkatapathy↗
NASA NTRS1987

Propfan test assessment propfan propulsion system static test report

The propfan test assessment (PTA) propulsion system successfully completed over 50 hours of extensive static ground tests, including a 36 hour endurance test. All major systems performed as expected, verifying that the large-scale 2.74 m diameter propfan, engine, gearbox, controls, subsystems, and flight instrumentation will be satisfactory with minor modifications for the upcoming PTA flight tests on the GII aircraft in early 1987. A test envelope was established for static ground operation to maintain propfan blade stresses within limits for propfan rotational speeds up to 105 percent and power levels up to 3880 kW. Transient tests verified stable, predictable response of engine power and propfan speed controls. Installed engine TSFC was better than expected, probably due to the excellent inlet performance coupled with the supercharging effect of the propfan. Near- and far-field noise spectra contained three dominant components, which were dependent on power, tip speed, and direction. The components were propfan blade tones, propfan random noise, and compressor/propfan interaction noise. No significant turbine noise or combustion noise was evident.

Orourke, D. M.↗
NASA NTRS2016

SLS Flight Software Testing: Using a Modified Agile Software Testing Approach

NASA's Space Launch System (SLS) is an advanced launch vehicle for a new era of exploration beyond earth's orbit (BEO). The world's most powerful rocket, SLS, will launch crews of up to four astronauts in the agency's Orion spacecraft on missions to explore multiple deep-space destinations. Boeing is developing the SLS core stage, including the avionics that will control vehicle during flight. The core stage will be built at NASA's Michoud Assembly Facility (MAF) in New Orleans, LA using state-of-the-art manufacturing equipment. At the same time, the rocket's avionics computer software is being developed here at Marshall Space Flight Center in Huntsville, AL. At Marshall, the Flight and Ground Software division provides comprehensive engineering expertise for development of flight and ground software. Within that division, the Software Systems Engineering Branch's test and verification (T&V) team uses an agile test approach in testing and verification of software. The agile software test method opens the door for regular short sprint release cycles. The idea or basic premise behind the concept of agile software development and testing is that it is iterative and developed incrementally. Agile testing has an iterative development methodology where requirements and solutions evolve through collaboration between cross-functional teams. With testing and development done incrementally, this allows for increased features and enhanced value for releases. This value can be seen throughout the T&V team processes that are documented in various work instructions within the branch. The T&V team produces procedural test results at a higher rate, resolves issues found in software with designers at an earlier stage versus at a later release, and team members gain increased knowledge of the system architecture by interfacing with designers. SLS Flight Software teams want to continue uncovering better ways of developing software in an efficient and project beneficial manner. Through agile testing, there has been increased value through individuals and interactions over processes and tools, improved customer collaboration, and improved responsiveness to changes through controlled planning. The presentation will describe agile testing methodology as taken with the SLS FSW Test and Verification team at Marshall Space Flight Center.

Bolton, Albanie T.↗
NASA NTRS2002

Propulsion Ground Testing with High Test Peroxide: Lessons Learned

Propulsion Ground Testing with High Test Peroxide (85 to 98% concentration) began at the NASA John C. Stennis Space Center in calendar year 1998, when the E3 Test Facility was modified to accomodate hydrogen peroxide (H2O2) in order to suport the research and development testing of the USAF Upper Stage Flight Experiment rocket engine. Since that time, efforts have continued to provide actual and planned test services to various customers, both U.S. Government and Commercial, in the ground test of many test articles, ranging from gas generators, to catalyst beds, to turbomachinery, to main injectors, to combustion chambers, to integrated rocket engines, to integrated stages. Along this path, and over the past 4 years, there has been both the rediscovery of previously learned lessons, through literature search, archive review, and personal interviews, as well as the learning of many new lessons as new areas are explored and new endeavors are tried. This paper will summarize those lessons learned in an effort to broaden the knowledge base as High Test Peroxide is considered more widely for use in rocket propulsion applications.

Bruce, Robert↗
NASA NTRS1992

Subsonic flight test evaluation of a propulsion system parameter estimation process for the F100 engine

An adaptive-performance-seeking control system which optimizes the quasi-steady-state performance of the F-15 propulsion system is discussed. This paper presents flight- and ground-test evaluations of the propulsion system parameter-estimation process used by the performance seeking control system. The estimator consists of a compact propulsion system model and an extended Kalman filter. The extended Kalman filter estimates five engine component deviation parameters from measured inputs. The compact model uses measurements and Kalman-filter estimates as inputs to predict unmeasured propulsion parameters such as net propulsive force and fan stall margin. The ability to track trends and estimate absolute values of propulsion system parameters was demonstrated. For example, thrust stand results show a good correlation especially in trends between the performance seeking control estimated and measured thrust.

Orme, John S.↗
NASA NTRS1987

Large-scale static investigation of circulation-control-wing concepts applied to upper surface-blowing aircraft

The use of a circulation control to deflect turbofan engine thrust beyond 90 deg. has been proven in full-scale static ground tests of the circulation-control-wing/upper-surface-blowing (CCW/USB) concept. This powered high-lift system employs a circular, blown trailing edge to replace the USB mechanical flaps to entrain engine-exhaust flow, and to obtain both a vertical-thrust component and an augmented circulation lift for short takeoff and landing (STOL) applications. Previous tests (Phase 1), done in 1982, of a basic configuration installed on the Quiet Short Haul Research Aircraft confirmed these CCW/USB systems capabilities. A second phase (Phase 2) of full-scale, static, thrust-deflection investigations has reconfirmed the ability to deflect engine thrust from 40 to 102 deg., depending on thrust level. Five new configurations were evaluated and performance improvements noted for those configurations with larger blown span, fences or favorable engine interactions, smaller slot height, and larger radii with less than 180 deg. of CCW surface arc. In general, a 90 deg. circular arc with a smaller slot height provided the best performance, demonstrating that adequate thrust turning can be produced by a trailing-edge shape which may have minimal cruise-performance penalty. Thrust deflections were achieved at considerably lower blowing momentum than was required for the baseline case of Phase 1. Improved performance and versatility were thus confirmed for the CCW/USB system applied to STOL aircraft, where the potential for developing a non-moving-parts pneumatic thrust deflector to rapidly vary horizontal force from thrust to drag, while maintaining constant vertical force, appears quite promising. The conversion from high-lift to lower-drag cruise mode by merely terminating the blowing provides an effective STOL aircraft system.

Shovlin, M. D.↗