Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “CYLINDRICAL CONFIGURATION”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Vertical-cavity surface-emitting phase shifter

This study proposes a novel technique for a 2D beam steering system using hybrid plasmonic phase shifters with a cylindrical configuration in a 2D periodic array suitable for LIDAR applications. A nanoscale VCSEP design facilitates a sub-wavelength spacing between individual phase shifters, yielding an expanded field of view and side lobes suppression. The proposed design includes a highly doped sub-micron silicon pillar covered by a thin layer of nonlinear material and an additional conductive metal layer. Characterization of a single VCSEP demonstrated a Free Spectral Range (FSR) of 53.28 ± 2.5 nm and a transmission variation of 3 dB, with V π L equal to 0.075 V-mm.

47 OTHER INSTRUMENTATION↗
NASA NTRS1972

Cylindrically shaped rope ladder

Cylindrical shaped ladder is rope net held in cylindrical configuration by supporting metal hoops which are spaced at vertical intervals along ladder. Rope ladder is easily handled and transported.

Range, C. S.↗
NASA NTRS1975

Bifurcation and collapse analysis of stringer and ring-stringer stiffened cylindrical shells with cutouts

Results for cylindrical configurations using the STAGS computer program were presented. Discontinuities were imposed upon the shell's skin by incorporating symmetrical cutout openings. In addition, the surface is stiffened with both stringer and ring-stringer arrangements. The cutout problem has been shown to be highly nonlinear for smooth surface shells, but it was found that bifurcation and collapse loads are close when one is considering stiffened skin configurations. In order to arrive at this conclusion, it was necessary to evaluate the following: (1) comparison between smeared and discrete stiffener theory for linear solutions, (2) numerical finite difference convergence as directed toward buckling determination, (3) collapse load results with the various skin stiffeners. A linear bifurcation study relating to stiffening effects around cutout areas present within stringer and ring-stringer shell surfaces was included. Comparisons were made between a variety of geometric positions considering cutout frame and thickened skin additions.

Palazotto, A. N.↗
NASA NTRS1980

Solar energy receiver for a Stirling engine

A solar energy receiver includes a separable endless wall formed of a ceramic material in which a cavity of substantially cylindrical configuration is defined for entrapping solar flux. An acceptance aperture is adapted to admit to the cavity a concentrated beam of solar energy. The wall is characterized by at least one pair of contiguously related segments separated by lines of cleavage intercepting the aperture. At least one of the segments is supported for pivotal displacement. A thermal-responsive actuator is adapted to respond to excessive temperatures within the cavity for initiating pivoted displacement of one segment, whereby thermal flux is permitted to escape from the cavity.

Selcuk, M. K.↗
NASA NTRS1981

Mobile sampler for use in acquiring samples of terrestrial atmospheric gases

Samples of terrestrial atmospheric gasses from a free body of such gasses using a device characterized by a plurality of tubular bodies adapted to be mounted in side by side relation on a motorized highway vehicle in mutual parallelism with the axis of the normal path of travel for the vehicles. Each of the bodies is of a cylindrical configuration and has an axial opening at each of its opposite ends through which a linear flow path is defined. A pair of pivotally supported, spring-biased sealing caps is mounted adjacent to the ends of the body and continuously urged into a hermetic sealing relationship. A restraint for securing the caps against spring-urged pivotal displacement, includes a separable, normally tensioned line interconnecting the caps and an operable release mechanism for simultaneously releasing the caps for spring-urged displacement. A hot wire cutter is included for separating the line, whereby samples of air are trapped in the body as the caps are spring-driven to assume an hermetically sealed relation with the openings defined in each of the opposite ends of the body.

Tucker, C. E.↗
NASA NTRS1985

Stable density stratification solar pond

A stable density-stratification solar pond for use in the collection and storage of solar thermal energy including a container having a first section characterized by an internal wall of a substantially cylindrical configuration and a second section having an internal wall of a substantially truncated conical configuration surmounting the first section in coaxial alignment therewith, the second section of said container being characterized by a base of a diameter substantially equal to the diameter of the first section and a truncated apex defining a solar energy acceptance opening is discussed. A body of immiscible liquids is disposed within the container and comprises a lower portion substantially filling the first section of the container and an upper portion substantially filling the second section of the container, said lower portion being an aqueous based liquid of a darker color than the upper portion and of a greater density. A protective cover plate is removably provided for covering the acceptance opening.

Lansing, F. L.↗
NASA NTRS1986

Fluidic angular velocity sensor

A fluidic sensor providing a differential pressure signal proportional to the angular velocity of a rotary input is described. In one embodiment the sensor includes a fluid pump having an impeller coupled to a rotary input. A housing forming a constricting fluid flow chamber is connected to the fluid input of the pump. The housing is provided with a fluid flow restrictive input to the flow chamber and a port communicating with the interior of the flow chamber. The differential pressure signal measured across the flow restrictive input is relatively noise free and proportional to the square of the angular velocity of the impeller. In an alternative embodiment, the flow chamber has a generally cylindrical configuration and plates having flow restrictive apertures are disposed within the chamber downstream from the housing port. In this embodiment, the differential pressure signal is found to be approximately linear with the angular velocity of the impeller.

Berdahl, C. M.↗
NASA NTRS1986

Analysis of thermomechanical oxidation fields in thermal barrier coatings

This paper considers the problem of the thermomechanical oxidation response of thermal barrier coatings. Overall, this involves the formulation of the requisite field equations and their associated boundary conditions, including the effects of oxide scale developing either on external surfaces or at interlaminar regions. To establish the potential effects of growing scale layers, the solution to the thermomechanical oxidation response of a cylindrically configured thermal barrier coating is developed. This includes handling the overall thermomechanical oxidation history.

Padovan, J.↗
NASA NTRS1987

Experimental evaluation of active noise control in a thin cylindrical shell

The effect of frequency on the performance of an active control system is examined. The effects are related to the mechanisms of the structural-acoustic coupling and the nature of the control field acoustics. The cylinder used in the experiment consists of a thin aluminum shell terminated with two end plates in a cylindrical configuration. The experiment was conducted at 324, 450, and 475 Hz, corresponding to shell nondimensional frequencies of Omega = 0.15, 0.21, and 0.22. It is found that the nature of the primary field is determined by the coupling between the shell and the acoustic space as well as the frequency of excitation.

Abler, Steven B.↗
NASA NTRS1989

Computation Of Flow About A Helicopter Rotor

Improved method developed to simulate numerically flow about helicopter rotor with multiple blades. Computes vortical wake beneath rotor without using simplified ad hoc mathematical models of effects in wake. Patched grids used in numerical simulation of flow about rotor blades. Cylindrical configuration simplifies interpolation at interface between rotating and stationary grids.

Chen, C. L.↗
NASA NTRS1992

Jet mixing into a heated cross flow in a cylindrical duct: Influence of geometry and flow variations

To examine the mixing characteristics of jets in an axi-symmetric can geometry, temperature measurements were obtained downstream of a row of cold jets injected into a heated cross stream. Parametric, non-reacting experiments were conducted to determine the influence of geometry and flow variations on mixing patterns in a cylindrical configuration. Results show that jet to mainstream momentum flux ratio and orifice geometry significantly impact the mixing characteristics of jets in a can geometry. For a fixed number of orifices, the coupling between momentum flux ratio and injector determines (1) the degree of jet penetration at the injection plane, and (2) the extent of circumferential mixing downstream of the injection plane. The results also show that, at a fixed momentum flux ratio, jet penetration decreases with (1) an increase in slanted slot aspect ratio, and (2) an increase in the angle of the slots with respect to the mainstream direction.

Hatch, M. S.↗
NASA NTRS1990

Computer program to solve two-dimensional shock-wave interference problems with an equilibrium chemically reacting air model

The computer program EASI, an acronym for Equilibrium Air Shock Interference, was developed to calculate the inviscid flowfield, the maximum surface pressure, and the maximum heat flux produced by six shock wave interference patterns on a 2-D, cylindrical configuration. Thermodynamic properties of the inviscid flowfield are determined using either an 11-specie, 7-reaction equilibrium chemically reacting air model or a calorically perfect air model. The inviscid flowfield is solved using the integral form of the conservation equations. Surface heating calculations at the impingement point for the equilibrium chemically reacting air model use variable transport properties and specific heat. However, for the calorically perfect air model, heating rate calculations use a constant Prandtl number. Sample calculations of the six shock wave interference patterns, a listing of the computer program, and flowcharts of the programming logic are included.

Glass, Christopher E.↗
NASA NTRS1992

Jet mixing into a heated cross flow in a cylindrical duct - Influence of geometry and flow variations

To examine the mixing characteristics of jets in an axi-symmetric can geometry, temperature measurements were obtained downstream of a row of cold jets injected into a heated cross stream. Parametric, non-reacting experiments were conducted to determine the influence of geometry and flow variations on mixing patterns in a cylindrical configuration. Results show that jet to mainstream momentum flux ratio and orifice geometry significantly impact the mixing characteristics of jets in a can geometry. For a fixed number of orifices, the coupling between momentum flux ratio and injector determines (1) the degree of jet penetration at the injection plane, and (2) the extent of circumferential mixing downstream of the injection plane. The results also show that, at a fixed momentum flux ratio, jet penetration decreases with (1) an increase in slanted slot aspect ratio, and (2) an increase in the angle of the slots with respect to the mainstream direction.

Hatch, M. S.↗
NASA NTRS1993

Stirling Engine With Radial Flow Heat Exchangers

Conflict between thermodynamical and structural requirements resolved. In Stirling engine of new cylindrical configuration, regenerator and acceptor and rejector heat exchangers channel flow of working gas in radial direction. Isotherms in regenerator ideally concentric cylinders, and gradient of temperature across regenerator radial rather than axial. Acceptor and rejector heat exchangers located radially inward and outward of regenerator, respectively. Enables substantial increase in power of engine without corresponding increase in diameter of pressure vessel.

Vitale, N.↗
NASA NTRS1993

Optimization of circular orifice jets mixing into a heated cross flow in a cylindrical duct

To examine the mixing characteristics of circular jets in an axisymmetric can geometry, temperature measurements were obtained downstream of a row of cold jet injected into a heated cross stream. The objective was to obtain uniform mixing within one duct radius downstream of the leading edge of the jet orifices. An area weighted standard deviation of the mixture fraction was used to help quantify the degree of mixedness at a given plane. Non-reacting experiments were conducted to determine the influence of the number of jets on the mixedness in a cylindrical configuration. Results show that the number of orifices significantly impacts the mixing characteristics of jets injected from round hole orifices in a can geometry. Optimum mixing occurs when the mean jet trajectory aligns with the radius which divides the cross sectional area of the can into two equal parts at one mixer radius downstream of the leading edge of the orifice. The optimum number of holes at momentum-flux ratios of 25 and 52 is 10 and 15 respectively.

Kroll, J. T.↗
NASA NTRS1993

Optimization of circular orifice jets mixing into a heated crossflow in a cylindrical duct

To examine the mixing characteristics of circular jets in an axisymmetric can geometry, temperature measurements were obtained downstream of a row of cold jet injected into a heated cross stream. The objective was to obtain uniform mixing within one duct radius downstream of the leading edge of the jet orifices. An area weighted standard deviation of the mixture fraction was used to help quantify the degree of mixedness at a given plane. Non-reacting experiments were conducted to determine the influence of the number of jets on the mixedness in a cylindrical configuration. Results show that the number of orifices significantly impacts the mixing characteristics of jets injected from round hole orifices in a can geometry. Optimum mixing occurs when the mean jet trajectory aligns with the radius which divides the cross sectional area of the can into two equal parts at one mixer radius downstream of the leading edge of the orifice. The optimum number of holes at momentum-flux ratios of 25 and 52 is 10 and 15 respectively.

Kroll, J. T.↗