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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Space shuttle plume/simulation application: Results and math model supersonic data

The analysis of pressure and gage wind tunnel data from space shuttle wind tunnel test IA138 was performed to define the aerodynamic influence of the main propulsion system and solid rocket booster plumes on the total vehicles, elements, and components of the space shuttle vehicle during the supersonic portion of ascent flight. A math model of the plume induced aerodynamic characteristics was developed for a range of Mach numbers to match the forebody aerodynamic math model. The base aerodynamic characteristics are presented in terms of forces and moments versus attitude. Total vehicle base and forebody aerodynamic characteristics are presented in terms of aerodynamic coefficients for Mach numbers from 1.55 to 2.5.

Boyle, W.↗
NASA NTRS1986

Review and evaluation of recent developments in melic inlet dynamic flow distortion prediction and computer program documentation and user's manual estimating maximum instantaneous inlet flow distortion from steady-state total pressure measurements with full, limited, or no dynamic data

A review of the Melick method of inlet flow dynamic distortion prediction by statistical means is provided. These developments include the general Melick approach with full dynamic measurements, a limited dynamic measurement approach, and a turbulence modelling approach which requires no dynamic rms pressure fluctuation measurements. These modifications are evaluated by comparing predicted and measured peak instantaneous distortion levels from provisional inlet data sets. A nonlinear mean-line following vortex model is proposed and evaluated as a potential criterion for improving the peak instantaneous distortion map generated from the conventional linear vortex of the Melick method. The model is simplified to a series of linear vortex segments which lay along the mean line. Maps generated with this new approach are compared with conventionally generated maps, as well as measured peak instantaneous maps. Inlet data sets include subsonic, transonic, and supersonic inlets under various flight conditions.

Schweikhard, W. G.↗
NASA NTRS1987

Research in Natural Laminar Flow and Laminar-Flow Control, part 3

Part 3 of the Symposium proceedings contains papers addressing advanced airfoil development, flight research experiments, and supersonic transition/laminar flow control research. Specific topics include the design and testing of natural laminar flow (NLF) airfoils, NLF wing gloves, and NLF nacelles; laminar boundary-layer stability over fuselage forebodies; the design of low noise supersonic/hypersonic wind tunnels; and boundary layer instability mechanisms on swept leading edges at supersonic speeds.

Hefner, Jerry N.↗
NASA NTRS1993

Multidisciplinary aeroelastic analysis of a generic hypersonic vehicle

This paper presents details of a flutter and stability analysis of aerospace structures such as hypersonic vehicles. Both structural and aerodynamic domains are discretized by the common finite element technique. A vibration analysis is first performed by the STARS code employing a block Lanczos solution scheme. This is followed by the generation of a linear aerodynamic grid for subsequent linear flutter analysis within subsonic and supersonic regimes of the flight envelope; the doublet lattice and constant pressure techniques are employed to generate the unsteady aerodynamic forces. Flutter analysis is then performed for several representative flight points. The nonlinear flutter solution is effected by first implementing a CFD solution of the entire vehicle. Thus, a 3-D unstructured grid for the entire flow domain is generated by a moving front technique. A finite element Euler solution is then implemented employing a quasi-implicit as well as an explicit solution scheme. A novel multidisciplinary analysis is next effected that employs modal and aerodynamic data to yield aerodynamic damping characteristics. Such analyses are performed for a number of flight points to yield a large set of pertinent data that define flight flutter characteristics of the vehicle. This paper outlines the finite-element-based integrated analysis procedures in detail, which is followed by the results of numerical analyses of flight flutter simulation.

Gupta, K. K.↗
NASA NTRS1993

Investigation of sonic boom for the Space Shuttle: High cross-range orbiter

Recent studies of a proposed low cross-range straight-wing space shuttle orbiter have shown that the sonic boom created during reentry may be objectionable, particularly at low supersonic Mach number. Because of this, additional tests have been conducted to determine the sonic-boom overpressure for a blended wing-body shape proposed for use as a high cross-range shuttle orbiter. Two mission profiles, in which a constant angle of attack was held during the supersonic portion of the flight, were studied. In one case the angle of attack was 60 degrees; in the other 25 degrees. The sonic-boom pressure signatures were measured in a wind tunnel and used to estimate overpressures for both missions. A technique for alleviating the boom is indicated.

Hicks, Raymond M.↗
NASA NTRS2020

How Loud is X-59's Shaped Sonic Boom?

NASA’s X-59 Quiet SuperSonic Technology low boom flight demonstrator aircraft is designed to produce a shaped sonic boom or “sonic thump” of 75 dB Perceived Level (PL) at the ground. One communication challenge that NASA’s Low Boom Flight Demonstration Mission faces is how to describe the sonic thump to the public, most of whom have never heard a sonic thump or a sonic boom. Furthermore, the public is unfamiliar with the acoustic metrics such as PL used to describe impulsive sounds. One technique to describe unfamiliar sounds using words and graphics only is to put them in the context of more familiar sounds, both in terms of acoustical level and in terms of sound type (continuous vs. impulsive). In this work, a database of recordings of familiar impulsive noise sources at known distances and their associated PL values was assembled and is available online. The comparison of these sounds can be framed as a “thermometer” of acoustic levels. An example acoustic thermometer graphic is presented. Additionally, the impulsive sounds’ one-third octave band sound pressure levels and sone spectra are compared to that of a simulated X-59 ground waveform. These show the origin of differences in the PL of each sound.

sonic boom↗
NASA NTRS2007

Overview of Experimental Capabilities - Supersonics

This viewgraph presentation gives an overview of experimental capabilities applicable to the area of supersonic research. The contents include: 1) EC Objectives; 2) SUP.11: Elements; 3) NRA; 4) Advanced Flight Simulator Flexible Aircraft Simulation Studies; 5) Advanced Flight Simulator Flying Qualities Guideline Development for Flexible Supersonic Transport Aircraft; 6) Advanced Flight Simulator Rigid/Flex Flight Control; 7) Advanced Flight Simulator Rapid Sim Model Exchange; 8) Flight Test Capabilities Advanced In-Flight Infrared (IR) Thermography; 9) Flight Test Capabilities In-Flight Schlieren; 10) Flight Test Capabilities CLIP Flow Calibration; 11) Flight Test Capabilities PFTF Flowfield Survey; 12) Ground Test Capabilities Laser-Induced Thermal Acoustics (LITA); 13) Ground Test Capabilities Doppler Global Velocimetry (DGV); 14) Ground Test Capabilities Doppler Global Velocimetry (DGV); and 15) Ground Test Capabilities EDL Optical Measurement Capability (PIV) for Rigid/Flexible Decelerator Models.

Banks, Daniel W.↗
NASA NTRS1977

Real-time testing of titanium sheet and extrusion coupon specimens subjected to Mach 2.7 supersonic cruise aircraft wing stresses and temperatures

The accuracy of three accelerated flight-by-flight test methods for material selection, and fatigue substantiation of supersonic cruise aircraft structure was studied. The real time stresses and temperatures applied to the specimens were representative of the service conditions in the lower surface of a Mach 2.7 supersonic cruise aircraft wing root structure. Each real time flight lasted about 65 minutes, including about one hour at (500 F) in the cruise condition. Center notched coupon specimens from six titanium materials were tested: mill-annealed, duplex-annealed, and triplex-annealed Ti-8Al-1Mo-1V sheets; mill-annealed Ti-8Al-1Mo-1V extrusion; mill-annealed Ti-6Al-4V sheet; and solution-treated and aged Ti-6Al-4V extrusion. For duplex-annealed Ti-8Al-1Mo-1V sheet, specimens with single spotweld were also tested. The test results were studied in conjunction with other related data from the literature for: material selection, structural fabrication, fatigue resistance of supersonic cruise aircraft structure, and fatigue test acceleration procedures for supersonic cruise aircraft.

Lunde, T.↗
NASA NTRSDate not supplied

Wall-Modeled Large-Eddy Simulation of Supersonic Parachute Inflation

Supersonic parachutes have been used in nearly every robotic mission to another planetary body with an atmosphere because they are one of the most mass-efficient ways to decelerate a payload to land on the surface. Short of performing flight tests in the upper Earth atmosphere, we currently cannot reliably predict a novel parachute system’s performance or potential failure modes, or even confidently explain it after the fact, as was the case with the Low Density Supersonic Decelerator flight tests and subsequent investigations. Fluid-structure interaction (FSI) simulations have the potential to bridge this gap. To this end, we present several improvements to the state-of-the-art for simulating supersonic parachutes using FSI: a higher effective resolution convective flux, an immersed boundary turbulent wall layer modeling approach to capture viscous effects, and a novel method to obtain a more realistic initial parachute shape. A recent supersonic parachute flight test is simulated and compared to measurements for the purposes of model validation.

ESM↗
NASA NTRS1989

Photo-sensitized ignition of hydrogen/oxygen mixtures for hypersonic flight vehicles

An approach toward improving supersonic ignition and combustion efficiency was investigated under a feasibility program with NASA-Ames. The idea is to selectively irradiate targetted species in the combustion zone. The ensuing photodissociation reactions produce highly reactive radicals which modify the gas phase kinetics. The overall objective of this research was to demonstrate photosensitized ignition of H2/O2 mixtures, and to gain a preliminary understanding of the ignition mechanism, especially as it pertains to the concept of supersonic combustion. To this end, a series of experiments were performed with a model sensitizer, NO2. At subatmospheric pressures and moderate temperatures (above 100 F), mixtures of H2/O2/NO2 are ignitable by a pulsed eximer laser at 308 nm, 115 to 200 mJ. Ignitability was found to be a function of NO2 pressure, temperature, laser energy per pulse, and laser lens focal length (fluence at focal volume). Mixtures could not be ignited in the absence of the sensitizer. While increasing temperature improved sensitized ignition in the lower temperature range, a retarding effect was observed at the highest temperatures. To more thoroughly understand these thermal effects, the UV-Vis and IR spectra of NO2 and H2/O2/NO2 mixtures were studied over the temperature range 70 to 900 F. Initially, increasing temperature shifts the N2O4 in a reversible reaction to 2 NO2 equilibrium toward NO2, favoring photochemical ignition. However, at still higher temperature, NO2 converts to non-absorbing NO + 1/2 O2, thus preventing photosensitized ignition.

Lavid, Moshe↗
NASA NTRS2000

An Entry Flight Controls Analysis for a Reusable Launch Vehicle

The NASA Langley Research Center has been performing studies to address the feasibility of various single-stage to orbit concepts for use by NASA and the commercial launch industry to provide a lower cost access to space. Some work on the conceptual design of a typical lifting body concept vehicle, designated VentureStar(sup TM) has been conducted in cooperation with the Lockheed Martin Skunk Works. This paper will address the results of a preliminary flight controls assessment of this vehicle concept during the atmospheric entry phase of flight. The work includes control analysis from hypersonic flight at the atmospheric entry through supersonic speeds to final approach and landing at subsonic conditions. The requirements of the flight control effectors are determined over the full range of entry vehicle Mach number conditions. The analysis was performed for a typical maximum crossrange entry trajectory utilizing angle of attack to limit entry heating and providing for energy management, and bank angle to modulation of the lift vector to provide downrange and crossrange capability to fly the vehicle to a specified landing site. Sensitivity of the vehicle open and closed loop characteristics to CG location, control surface mixing strategy and wind gusts are included in the results. An alternative control surface mixing strategy utilizing a reverse aileron technique demonstrated a significant reduction in RCS torque and fuel required to perform bank maneuvers during entry. The results of the control analysis revealed challenges for an early vehicle configuration in the areas of hypersonic pitch trim and subsonic longitudinal controllability.

Calhoun, Philip↗
NASA NTRS2003

The Future of Flight

This paper presents viewgraphs on supersonic transports, hypersonic planes, runway-independent aircraft, and small personal aircraft which are possibilities for the aircraft of the future.

Springer, Anthony M.↗
NASA NTRS1996

A historical perspective of the YF-12A thermal loads and structures program

Around 1970, the Y-F-12A loads and structures efforts focused on numerous technological issues that needed defining with regard to aircraft that incorporate hot structures in the design. Laboratory structural heating test technology with infrared systems was largely created during this program. The program demonstrated the ability to duplicate the complex flight temperatures of an advanced supersonic airplane in a ground-based laboratory. The ability to heat and load an advanced operational aircraft in a laboratory at high temperatures and return it to flight status without adverse effects was demonstrated. The technology associated with measuring loads with strain gages on a hot structure was demonstrated with a thermal calibration concept. The results demonstrated that the thermal stresses were significant although the airplane was designed to reduce thermal stresses. Considerable modeling detail was required to predict the heat transfer and the corresponding structural characteristics. The overall YF-12A research effort was particularly productive, and a great deal of flight, laboratory, test and computational data were produced and cross-correlated.

Jenkins, Jerald M.↗
NASA NTRS1987

Flight and analytical investigations of a structural mode excitation system on the YF-12A airplane

A structural excitation system, using an oscillating canard vane to generate force, was mounted on the forebody of the YF-12A airplane. The canard vane was used to excite the airframe structural modes during flight in the subsonic, transonic, and supersonic regimes. Structural modal responses generated by the canard vane forces were measured at the flight test conditions by airframe-mounted accelerometers. Correlations of analytical and experimental aeroelastic results were made. Doublet lattice, steady state double lattice with uniform lag, Mach box, and piston theory all produced acceptable analytical aerodynamic results within the restrictions that apply to each. In general, the aerodynamic theory methods, carefully applied, were found to predict the dynamic behavior of the YF-12A aircraft adequately.

Goforth, E. A.↗
NASA NTRSDate not supplied

A Database of CFD-Based Buffet Forcing Functions for Artemis I Structural Response Evaluation

Time-accurate FUN3D simulations are utilized to estimate buffet-induced unsteady forces experienced by the Space Launch System during the Artemis I (AR01) flight. A set of FUN3D simulations was developed that employed time-accurate mesh translations to simulate the changing velocity and attitude based on the AR01 best estimated trajectory. In these simulations, referred to as accelerating-flow simulations, the freestream Mach number increased from 0.80 to 1.92. Additional time-accurate simulations were obtained at constant freestream Mach number equal to 0.95, 1.18, 1.70, thereby simulating stationary conditions experienced by the flow in a wind-tunnel. On the grounds of favorable comparisons between simulated and flight-measured environments, the FUN3D-based surface pressures were utilized to develop a buffet forcing function (BFF) database. This BFF database was analyzed to characterize the spatial distribution and frequency content of the buffet forces during transonic and supersonic portions of the AR01 flight. The region of interest is located downstream of the forward attachment (FA) hardware between the core stage and the solid rocket boosters where vortex shedding off the FA protuberance produces significant unsteadiness. The analysis reveals that, at transonic and supersonic conditions, buffet forces that are based on constant freestream Mach number data are a good approximation of those based on accelerating-flow simulations.

FUN3D↗