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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1948

Ice Protection of Turbojet Engines by Inertia Separation of Water II : Single-offset-duct System

Investigation of a single-offset-duct system designed to prevent entrance of water into a turbojet engine was conducted on a half-scale nacelle model. An investigation was made to determine ram-pressure recovery and radial velocity profiles at the compressor section and icing characteristics of such a duct system. At a design inlet velocity of 0.77, the maximum ram-pressure recovery attained with effective water-separating inlet was 77 percent, which is considerably less than attainable with a direct-ram inlet. Continuous heating of the accessory-housing surface would be required for inlets that have a small ice storage space.

NOSE SHAPE - DUCTED BODIES↗
NASA NTRS1970

Quick calculation method for fluid flow through duct systems

Conditions for subsonic compressible flow through duct systems are quickly and easily calculated using compact series of curves showing dimensionless parametric functions of Mach number and specific heat ratio. Method is directly applicable to analysis and design of compressible flow systems in industrial fields or processes.

Scott, L. R., Jr.↗
NASA NTRS1994

Modeling dynamically coupled fluid-duct systems with finite line elements

Structural analysis of piping systems, especially dynamic analysis, typically considers the duct structure and the contained fluid column separately. Coupling of these two systems, however, forms a new dynamic system with characteristics not necessarily described by the superposition of the two component system's characteristics. Methods for modeling the two coupled components simultaneously using finite line elements are presented. Techniques for general duct intersections, area or direction changes, long radius bends, hydraulic losses, and hydraulic impedances are discussed. An example problem and results involving time transients are presented. Additionally, a program to enhance post-processing of line element models is discussed.

Saxon, J. B.↗
NASA NTRS1948

Ice Protection of Turbojet Engines by Inertia Separation of Water I : Alternate-duct System

Aerodynamic and icing investigations of internal water-inertia separation inlets designed to prevent automatically entrance of large quantities of water into a turbojet engine in icing conditions was conducted on a one-half scale model. A simplified analytical approach to the design of internal water-inertia separation inlets is included. Results show that in order to be effective in preventing screen and guide-vane icing for an inlet of this type, a ram-pressure recovery of 75 percent was attained at design inlet-velocity ratio in an icing condition. For nonicing operation, ram-pressure recovery is comparable to direct-ram inlet.

INLETS, NOSE - CENTRAL↗
NASA NTRS1973

The acoustics of aircraft engine-duct systems

Noise generated in aircraft engines is usually suppressed by acoustically treating the engine ducts. The optimization of this treatment requires an understanding of the transmission and attenuation of the acoustic waves. A critical review is presented of the state of the art regarding methods of determining the transmission and attenuation parameters and the effect on these parameters of (1) acoustic properties of liners, (2) the mean velocity, including uniform and shear profiles and nonparallel flow, (3) axial and transverse temperature gradients, (4) slowly and abruptly varying cross sections, and (5) finite-amplitude waves and nonlinear duct liners.

Nayfeh, A. H.↗
NASA NTRS1966

Bellows joint absorbs torsional deflections in duct system

Long, thin-walled bellows compressed into a short length absorbs the same amount of torsional deflection as the same tube in full length condition and saves in cost, complexity and space. This bellows has lower torsional spring rate to absorb the bulk of the duct assembly tortional deflections, leaving the other bellows free to absorb axial and angular deflections.

Daniels, C. M.↗
NASA NTRS1980

Elimination of a discrete frequency acoustical phenomenon associated with the Space Shuttle main engine oxidizer valve-duct system

In the development of the Space Shuttle Main Engines, various unpredictable dynamical phenomena were experienced which resulted in engine shutdown or failures, e.g., fires. One such dynamical phenomenon consisted of an acoustical buzz at 7200 Hz in the vicinity of the main oxidizer valve. The method of isolating the buzz phenomenon, identifying the mechanism, and developing a fix to eliminate the buzz is presented together with supporting data. These data, i.e., fluctuating pressure and acceleration data, were obtained from hot firing engine tests and from liquid nitrogen flow simulation tests conducted at Marshall Space Flight Center.

Schutzenhofer, L. A.↗
NASA NTRS1941

Cooling Tests of an Airplane Equipped with an NACA Cowling and a Wing-duct Cooling System

Cooling tests were made of a Northrop A-17A attack airplane successively equipped with a conventional.NACA cowling and with a wing-duct cooling system. The method of cooling the engine by admitting air from the propeller slipstream into wing ducts, passing it first through the accessory compartment and then over the engine from rear to front, appeared to offer possibilities for improved engine cooling, increased cooling of the accessories, and better fairing of the power-plant installation. The results showed that ground cooling for the wing duct system without cowl flap was better than for the NACA cowling with flap; ground cooling was appreciably improved by installing a cowl flap. Satisfactory temperatures were maintained in both climb and high-speed flight, but, with the use of conventional baffles, a greater quantity of cooling air appeared to be required for the wing duct system.

Turner, L I , Jr↗
NASA NTRS1980

Analysis of pressure spectra measurements in a ducted combustion system

Combustion noise propagation in an operating ducted liquid fuel combustion system is studied in relation to the development of combustion noise prediction and suppression techniques. The presence of combustor emissions in the duct is proposed as the primary mechanism producing the attenuation and dispersion of combustion noise propagating in an operating liquid fuel combustion system. First, a complex mathematical model for calculating attenuation and dispersion taking into account mass transfer, heat transfer, and viscosity effects due to the presence of liquid fuel droplets or solid soot particles is discussed. Next, a simpler single parameter model for calculating pressure auto-spectra and cross-spectra which takes into account dispersion and attenuation due to heat transfer between solid soot particles and air is developed. Then, auto-spectra and cross-spectra obtained from internal pressure measurements in a combustion system consisting of a J-47 combustor can, a spool piece, and a long duct are presented. Last, analytical results obtained with the single parameter model are compared with the experimental measurements. The single parameter model results are shown to be in excellent agreement with the measurements.

Miles, J. H.↗