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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Experimental aerodynamic evaluation of the SSME two-duct, hot gas manifold

An investigation was performed on an improved Space Shuttle Main Engine (SSME) hot gas manifold (HGM) design using a full scale HGM model in cold-flow, air-blowdown tests. The new HGM design replaces the current three transfer ducts with two enlarged elliptical transfer ducts, faired duct inlets, and enlarged fuel bowl. Extensive experimental results have been obtained to verify previous results showing that the two-duct design improved the HGM internal flow path by eliminating separated flow regions, reducing high local velocities, and providing more uniform flow.

Kim, B. Y.↗
NASA NTRS1966

Summary of large-scale test of ducted fans

Several research areas which have been investigated by the NASA on large scale isolated ducted fan models are discussed. Research concerned with per­formance has indicated that: (1) ducted fan inlet design does not appear to be a major problem, (2) ducted fan nacelles must be very carefully designed, other­wise the drag becomes excessive, and (3) increasing fan tip clearance reduces the shroud thrust and reduces the capability of the fan for absorbing power. Research concerned with the occurrence of duct lip stall due to angle of attack indicates that neither inner nor outer duct lip stall for reasonably sized ducted fans is the problem that it was once considered to be.

VTOL AIRCRAFT↗
NASA NTRS1972

Automatic air flow control in air conditioning ducts

Device is designed which automatically selects air flow coming from either of two directions and which can be adjusted to desired air volume on either side. Device uses one movable and two fixed scoops which control air flow and air volume.

Obler, H. D.↗
NASA NTRS1991

Aeroacoustics of Flight Vehicles: Theory and Practice. Volume 2: Noise Control

Flight vehicles and the underlying concepts of noise generation, noise propagation, noise prediction, and noise control are studied. This volume includes those chapters that relate to flight vehicle noise control and operations: human response to aircraft noise; atmospheric propagation; theoretical models for duct acoustic propagation and radiation; design and performance of duct acoustic treatment; jet noise suppression; interior noise; flyover noise measurement and prediction; and quiet aircraft design and operational characteristics.

Hubbard, Harvey H.↗
NASA NTRS1979

Analysis, design, and test of acoustic treatment in a laboratory inlet duct

A suppression prediction program based on the method of modal analysis for spinning mode propagation in a circular duct was used in the analytical design of optimized, multielement, Kevlar bulk-absorber treatment configurations for an inlet duct. The NASA-Langley ANRL anechoic chamber using the spinning mode synthesizer as a sound source was used to obtain in-duct spinning mode measurements, radial mode measurements, and far-field traverses, as well as aerodynamic measurements. The measured suppression values were compared to predicted values, using the in-duct, forward-traveling, radial-mode content as the source for the prediction. The performance of the treatment panels was evaluated from the predicted and measured data. Although experimental difficulties were encountered at the design condition, sufficient information was obtained to confirm the expectation that it is the panel impedance components which are critical to suppression at a single frequency, not the particular construction materials. The agreement obtained between measurement and prediction indicates that the analytical program can be used as an accurate, reliable, and useful design tool.

Kraft, R. E.↗
NASA NTRS1947

Effect of Modifications to Induction System on Altitude Performance of V-1710-93 Engine III : Use of Parabolic Rotating Guide Vanes and NACA Designed Auxiliary-stage Inlet Elbow and Interstage Duct

Bench runs of a modified V-1710-93 engine equipped with a two-stage supercharger, interstage carburetor, aftercooler assembly, and backfire screens have been made at a simulated altitude of 29,000 feet to determine the effect of several induction-system modifications on the engine and supercharger performance. The standard guide vanes on the auxiliary- and engine-stage superchargers were replaced by rotating guide vanes with a parabolic blade profile. The auxiliary-stage inlet elbow and interstage duct were replaced with new units of NACA design. These modifications were made one at a time and data were obtained after each change to determine the effect of each modification. All runs were made at a constant engine speed of 3000 rpm at a simulated altitude of 29,000 feet and all changes in engine power were made by varying the speed of the auxiliary-stage supercharger.

Standahar, Ray M↗
NASA NTRS1990

Computational analysis of flow in 3D propulsive transition ducts

A numerical analysis of fully three dimensional, statistically steady flows in propulsive transition ducts being considered for use in future aircraft of higher maneuverability is investigated. The purpose of the transition duct is to convert axisymmetric flow from conventional propulsion systems to that of a rectangular geometry of high aspect ratio. In an optimal design, the transition duct would be of minimal length in order to reduce the weight penalty, while the geometrical change would be gradual enough to avoid detrimental flow perturbations. Recent experiments conducted at the Propulsion Aerodynamics Branch have indicated that thrust losses in ducts of superelliptic cross-section can be surprisingly low, even if flow separation occurs near the divergent walls. In order to address the objective of developing a rational design procedure for optimal transition ducts, it is necessary to have available a reliable computational tool for the analysis of flows achieved in a sequence of configurations. Current CFD efforts involving complicated geometries usually must contend with two separate but interactive aspects: namely, grid generation and flow solution. The first two avenues of the present investigation were comprised of suitable grid generation for a class of transition ducts of superelliptic cross-section, and the subsequent application of the flow solver PAB3D to this geometry. The code, PAB3D, was developed as a comprehensive tool for the solution of both internal and external high speed flows. The third avenue of investigation has involved analytical formulations to aid in the understanding of the nature of duct flows, and also to provide a basis of comparison for subsequent numerical solutions. Numerical results to date include the generation of two preliminary grid systems for duct flows, and the initial application of PAB3D to the corresponding geometries, which are of the class tested experimentally.

Sepri, Paavo↗
NASA NTRS1995

Computer-Simulation Surrogates for Optimization: Application to Trapezoidal Ducts and Axisymmetric Bodies

Engineering design and optimization efforts using computational systems rapidly become resource intensive. The goal of the surrogate-based approach is to perform a complete optimization with limited resources. In this paper we present a Bayesian-validated approach that informs the designer as to how well the surrogate performs; in particular, our surrogate framework provides precise (albeit probabilistic) bounds on the errors incurred in the surrogate-for-simulation substitution. The theory and algorithms of our computer{simulation surrogate framework are first described. The utility of the framework is then demonstrated through two illustrative examples: maximization of the flowrate of fully developed ow in trapezoidal ducts; and design of an axisymmetric body that achieves a target Stokes drag.

Otto, John C.↗
NASA NTRS2003

Investigation of Pneumatic Inlet and Diffuser Blowing on a Ducted Fan Propulsor in Static Thrust Operation

Tilting ducted fans present a solution for the lifting and forward flight propulsion requirements of VTOL aircraft. However, the geometry of the duct enshrouding the propeller has great a effect on the efficiency of the fan in various flight modes. Shroud geometry controls the velocity and pressure at the face of the fan, while maintaining a finite loading out at the tips of the fan blades. A duct tailored for most efficient generation of static lifting thrust will generally suffer from performance deficiencies in forward flight. The converse is true as well, leaving the designer with a difficult trade affecting the overall performance and sizing of the aircraft. Ideally, the shroud of a vertical lifting fan features a generous bell mouth inlet promoting acceleration of flow into the face of the fan, and terminating in a converging nozzle at the exit. Flow entering the inlet is accelerated into the fan by the circulation about the shroud, resulting in an overall increase in thrust compared to an open propeller operating under the same conditions . The accelerating shroud design is often employed in lifting ducted fans to benefit from the thrust augmentation; however, such shroud designs produce significant drag penalties in axial flight, thus are unsuitable for efficient forward flight applications. Decelerating, or diffusing, duct designs are employed for higher speed forward flight configurations. The lower circulation on the shroud tends to decelerate the flow into the face of the fan, which is detrimental to static thrust development; however, net thrust is developed on the shroud while the benefits of finite blade loading are retained. With judicious shroud design for intended flight speeds, a net increase in efficiency can be obtained over an open propeller. In this experiment, conducted under contract to NASA LaRC (contract NAG-1-02093) circulation control is being applied to a mildly diffusing shroud design, intended for improved forward flight performance, to generate circulation in the sense of an accelerating duct design. The intent is to improve static thrust performance of a ducted fan tailored for high speed axial flight, while at the same time significantly reduce the pressure signature on the ground plane. Circulation control on the fan shroud is achieved by the Coanda effect.

Kondor, Shayne↗
NASA NTRS1995

Advanced liquid oxygen (LO2) propellant conditioning concept testing

Advanced methods of liquid oxygen (LO2) propellant conditioning were studied as part of an effort for increasing reliability and operability while reducing cost of future heavy lift launch vehicles. The most promising conditioning concept evaluated was no-bleed (passive recirculation) followed by low-bleed, helium injection, and use of a recirculation line. Full-scale cryogenic testing was performed with a sloped feedline test article to validate models of behavior of LO2 in the feedline and to prove no-bleed feasibility. Test data are also intended to help generate design guidelines for the development of a main propulsion system feed duct. A design-of-experiments matrix of over 100 tests was developed to test all four propellant conditioning concepts and the impact of design parameters on the concepts. Liquid nitrogen was used as the test fluid. The work for this project was conducted from October 1992 through January 1994 at the hydrogen cold flow facility of the west test area of MSFC. Test data have shown that satisfactory temperatures are being obtained for the no-bleed conditioning concept.

Perry, G. L. E.↗
NASA NTRS1985

Aerodynamic evaluation of the redesigned Space Shuttle Main Engine hot-gas manifold

The current Space Shuttle Main Engine hot-gas manifold configuration contains three transfer ducts connecting the fuel bowl and the main injector torus. For the current study, a new hot-gas manifold was designed to improve on a previously tested two-duct concept. This was accomplished by eliminating separated flow regions, reducing local velocities, and providing as uniform a flowfield as possible. The two-duct hot-gas manifold tested in this study showed significant improvement over the existing three-duct design. The circumferential pressure gradient was reduced by 67 percent. The system total pressure loss from the discharge of the 180-degree turn to the transfer duct exit was 60 percent less than with the three duct hot gas manifold. Although only limited fluctuating pressure data were taken in the main injector, indications are that the environment there has been improved.

Vogt, S. T.↗
NASA NTRS1982

Gas flow environment and heat transfer nonrotating 3D program

A complete set of benchmark quality data for the flow and heat transfer within a large rectangular turning duct is provided. These data are to be used to evaluate, and verify, three-dimensional internal viscous flow models and computational codes. The analytical contract objective is to select a computational code and define the capabilities of this code to predict the experimental results obtained. Details of the proper code operation will be defined and improvements to the code modeling capabilities will be formulated. Internal flow in a large rectangular cross-sectioned 90 deg. bend turning duct was studied. The duct construction was designed to allow detailed measurements to be made for the following three duct wall conditions: (1) an isothermal wall with isothermal flow; (2) an adiabatic wall with convective heat transfer by mixing between an unheated surrounding flow; and (3) an isothermal wall with heat transfer from a uniformly hot inlet flow.

Schulz, R. J.↗
NASA NTRS1938

Full-Scale Wind-Tunnel Investigation of Wing Cooling Ducts, Special Report

The systematic investigation of wing cooling ducts at the NACA laboratory has been continued with tests in the full-scale wind tunnel on ducts of finite span. These results extend the previous investigation on section characteristics of ducts to higher Reynolds numbers and indicate the losses due to the duct ends. The data include comparisons between ducts completely within the ring and the conventional underslung ducts. Methods of flow regulation were studied and data were obtained for a wide range of internal duct resistance. The results show satisfactory correlation between the finite span and the previously measured section characteristics obtained with full-span ducts. The effects of the various design parameters on the duct characteristics are discussed. The cooling power required for the internal duct installation is shown to be only a small percentage of the engine power.

Nickle, F. R.↗
NASA NTRS1996

Vortex generator installation studies on steady state and dynamic inlet distortion

The theoretical and experimental work carried out under the NASA/MOD Joint Aeronautical Program has shown that CFD vortex generator installations designs successfully managed inlet duct flow distortion and that significant benefits in flow unsteadiness at the engine face were also present. The main conclusions to date from the collaborative effort between NASA/Lewis and DRA/Bedford are as follows: (1) vortex generator installations can be designed to be effective over a wide range of inlet operating conditions using Computational Fluid Dynamics and formal optimization procedures, (2) reductions in steady state engine face distortion of up to 80% have been measured in the M2129 inlet S-duct using CFD designed vortex generator installations, (3) reductions in flow unsteadiness of up to 80% have been measured in the W129 inlet S-duct using CFD designed vortex generator installations, and (4) the Reduced Navier-Stokes code RNS3D is a useful tool to design vortex generator installations to manage engine face distortions over a wide range of inlet operating conditions.

Anderson, Bernhard H.↗
NASA NTRS1976

Experimental-analytical correlation of optimum duct acoustic liner performance

Mode matching and segmented duct analytical models have been developed to take advantage of relative placement of liner segments in the design of optimal duct acoustic liners of one, two, and three segments. This paper presents experimental results which were obtained for liners installed in a rectangular duct for the case with no mean airflow through the duct. Excellent correlation is shown between the analytical and experimental data, thus verifying the analytical procedures used to design the optimum segmented lining configurations.

Patterson, J. D.↗
NASA NTRSDate not supplied

NASA’s Quiet Electric ENgines (QUEEN): Summary of the QUEEN V2 Test

A liquid-cooled electric ducted fan system was designed, built, and tested at the NASA Glenn Research Center. Main components of the system include a Commercial-Off- the-Shelf (COTS) fan and motor, and a custom-designed heat exchanger integrated into the fan duct. Fan speed, thrust, and cooling system thermal performance was measured in this static ground test of the propulsor. This propulsor prototype is one of NASA’s Quiet Electric ENgines (QUEENs) and is designated the ‘QUEEN V2.’ The Quiet Electric Engines are being developed for the 25% scale model of the Subsonic Aft Engine (SUSAN) Flight Research Vehicle and are intended to explore the potential of distributed electric propulsion for regional single-aisle aircraft. This test demonstrated the functionality of the QUEEN V2, quantified the thrust produced by the electrofan, and characterized the electrical and thermal performance of the system. Lessons learned will be used to guide development of future QUEEN prototypes.

Aerodynamics↗