Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “ventilators”

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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

Highlights of Aeroacoustic Tests of a Metal Spacecraft Cabin Ventilation Fan Prototype

A metal spacecraft cabin ventilation fan suitable for aerodynamic and acoustic ground tests was designed and tested in the NASA Glenn Research Center Acoustical Testing Laboratory. The fan design featured a low-noise blade-vane count that was chosen to reduce the rotor-stator interaction tone noise. The fan was throttled through its operating range, and results indicated that the measured aerodynamic and acoustic performance was in good agreement with predictions. Recommendations for further research of quiet high-performance fans intended to support long duration human space exploration missions are offered. This small fan aerodynamic and acoustic test rig and the NASA Glenn Acoustical Testing Laboratory are valuable resources available for supporting NASA’s aeronautics research and space exploration missions.

Fan, Noise, Ventilation↗
NASA NTRS2023

Quiet Spacecraft Cabin Ventilation Fan: Vibration Measurements Results

Quiet, efficient fans with minimal vibrations are needed to maximize the mechanical life of atmospheric revitalization system fans used for human life support systems for long duration space exploration missions. Several metal spacecraft cabin ventilation fan prototypes have been designed, built, and tested at the NASA Glenn Research Center Acoustical Testing Laboratory. Tests performed in 2021 of the first prototype of the metal fan measured vibrations greater than desired at design point speed and backpressure conditions. To try to reduce those vibrations, a second prototype of the fan design was developed which included a new lighter rotor with a tighter balance tolerance, a new collet to attach the rotor to the motor shaft more securely and repeatably, and a new bracket to center and hold the motor in the fan centerbody more precisely. The second prototype of the fan was tested in 2023 and the vibrations were measured with the fan operating at design point speeds in isolation but not throttled to design point back pressure conditions since it was not installed with inlet and exhaust ducting. Peak vibration was reduced from 4 mm/s to 1 mm/s. This paper is part of a series of reports documenting the performance of the prototype fan.

Fan↗
NASA NTRSDate not supplied

Spacecraft Cabin Ventilation Fan: Wake Measurements Results

Quiet, efficient fans with minimal vibrations are required for revitalization system fans used for human support system in long duration space exploration missions. A spacecraft cabin ventilation fan suitable for aerodynamic and acoustic ground tests was designed in NASA Glenn research center. Two copies of the fan assembly were fabricated and tested for aerodynamic performance and acoustic levels in the NASA Glenn Research Center Acoustical Testing Laboratory. A new test rig for small axial flow fans was designed to accommodate the instrumentation and back-pressure adjustments. Measurements acquired were from: static pressures for measuring performance, a 72-channel in-duct microphone array, external microphone measurements for acoustics, and inter-stage hot-wire measurements of the fan wake. Hot-wire measurements were obtained by radially traversing a x-wire probe downstream of the rotor. This report documents the phase-locked wake velocity, flow angle and turbulence measurements from the hot-wire surveys as part of a series of reports.

Hotwire Measurement↗
NASA NTRSDate not supplied

Quiet Spacecraft Cabin Ventilation Fan: Vibration Measurements Results

The vibrations of a metal spacecraft cabin ventilation fan that tested in 2021 were greater than desired. We diagnosed the problem and modified the rotor assembly in 2022 to try and reduce those vibrations. The design changes included a new lighter rotor with a tighter balance tolerance, a new collet to attach the rotor to the motor shaft more securely and repeatably, and a new bracket to center and hold the motor a little better. The redesigned rotor was tested in 2023 and vibrations were significantly reduced. The measured peak vibration was reduced from 4 mm/s second to less than 1 mm/s, corresponding to a reduction from a balance grade G4 to a grade G 0.6.

Fan, Noise, Ventilation↗
NASA NTRS2012

Acoustic Measurements of an Uninstalled Spacecraft Cabin Ventilation Fan Prototype

Sound pressure measurements were recorded for a prototype of a spacecraft cabin ventilation fan in a test in the NASA Glenn Acoustical Testing Laboratory. The axial fan is approximately 0.089 m (3.50 in) in diameter and 0.223 m (9.00 in) long and has nine rotor blades and eleven stator vanes. At design point of 12,000 rpm, the fan was predicted to produce a flow rate of 0.0709 m3/s (150 cfm) and a total pressure rise of 925 Pa (3.72 in. of water) at 12,000 rpm. While the fan was designed to be part of a ducted atmospheric revitalization system, no attempt was made to throttle the flow or simulate the installed configuration during this test. The fan was operated at six speeds from 6,000 rpm to 13,500 rpm. A 13-microphone traversing array was used to collect sound pressure measurements along two horizontal planes parallel to the flow direction, two vertical planes upstream of the fan inlet and two vertical planes downstream of the fan exhaust. Measurements indicate that sound at blade passing frequency harmonics contribute significantly to the overall audible noise produced by the fan at free delivery conditions.

fan↗
NASA NTRS1972

Digital simulation and experimental evaluation of the CO2-H(plus) control of pulmonary ventilation

Previous models of the CO2-H(+) control of ventilation have been concerned either with the response to CO2 inhalation, or the response to perfusion of the surface of the medulla with mock cerebrospinal fluid having a high P sub CO2. Simulation of both responses with the same model has not been attempted. The purpose of the present study was two fold; first to develop such a model and, second, to obtain experimental data from human subjects for both developing this model and for evaluating this and future models.

Milhorn, H. T., Jr.↗
NASA NTRS1972

Computation of wall effects in ventilated transonic wind tunnels.

A method for computing interference effects due to ventilated wind-tunnel walls on lifting transonic airfoils is presented. Differences between the present method based on nonlinear transonic theory and the classical correction formulae from linear subsonic theory are discussed. Computed results are presented for an NACA 0012 in solid and perforated wall tunnels. The solid wall calculations are compared with data.

Murman, E. M.↗
NASA NTRS1972

Experimental evaluation of the Skylab orbital workshop ventilation system concept

Extensive testing was conducted to evaluate the Orbital Workshop ventilation concept. Component tests were utilized to determine the relationship between operating characteristics at 1 and 0.34 atm. System tests were conducted at 1 atm within the Orbital Workshop full-scale mockup to assess delivered volumetric flow rate and compartment air velocities. Component tests with the Anemostat circular diffusers (plenum- and duct-mounted) demonstrated that the diffuser produced essentially equivalent airflow patterns and velocities in 1- and 0.34-atm environments. The tests also showed that the pressure drop across the diffuser could be scaled from 1 to 0.34 atm using the atmosphere pressure ratio. Fan tests indicated that the performance of a multiple, parallel-mounted fan cluster could be predicted by summing the single-fan flow rates at a given delta P.

Allums, S. L.↗
NASA NTRS1974

Technology evaluation of heating, ventilation, and air conditioning for MIUS application

Potential ways of providing heating, ventilation, and air conditioning for a building complex serviced by a modular integrated utility system (MIUS) are examined. Literature surveys were conducted to investigate both conventional and unusual systems to serve this purpose. The advantages and disadvantages of the systems most compatible with MIUS are discussed.

Gill, W. L.↗
NASA NTRS1979

Computation of aerodynamic interference effects on oscillating airfoils with controls in ventilated subsonic wind tunnels

Lift interference effects are discussed based on Bland's (1968) integral equation. A mathematical existence theory is utilized for which convergence of the numerical method has been proved for general (square-integrable) downwashes. Airloads are computed using orthogonal airfoil polynomial pairs in conjunction with a collocation method which is numerically equivalent to Galerkin's method and complex least squares. Convergence exhibits exponentially decreasing error with the number n of collocation points for smooth downwashes, whereas errors are proportional to 1/n for discontinuous downwashes. The latter can be reduced to 1/n to the m+1 power with mth-order Richardson extrapolation (by using m = 2, hundredfold error reductions were obtained with only a 13% increase of computer time). Numerical results are presented showing acoustic resonance, as well as the effect of Mach number, ventilation, height-to-chord ratio, and mode shape on wind-tunnel interference. Excellent agreement with experiment is obtained in steady flow, and good agreement is obtained for unsteady flow.

Fromme, J. A.↗
NASA NTRS1984

Wind tunnel wall interference in closed, ventilated and adaptive test sections

A wall interference correction method for closed rectangular test sections was developed which uses measured wall pressures. Measurements with circular discs for blockage and a rectangular wing as a lift generator in a square closed test section validate this method. These measurements are intended to be a basis of comparison for measurements in the same tunnel using ventilated (in these case, slotted) walls. Using the vortex lattice method and homogeneous boundary conditions, calculations were performed which show sufficiently high pressure levels at the walls for correction purposes in test sections with porous walls. In Gottingen, an adaptive test section (which is a deformable rubber tube of 800 mm diameter) was built and a computer program was developed which is able to find the necessary wall adaptation for interference-free measurements in a single step. To check the program prior to the first run, the vortex lattice method was used to calculate wall pressure distributions in the nonadapted test section as input data for the one-step method. Comparison of the pressure distribution in the adapted test section with free-flight data shows nearly perfect agreement. An extension of the computer program can be made to evaluate the remaining interference corrections.

Holst, H.↗
NASA NTRS1984

Performance of two transonic airfoil wind tunnels utilizing limited ventilation

A limited-zone ventilated wall panel was developed for a closed-wall icing tunnel which permitted correct simulation of transonic flow over model rotor airfoil sections with and without ice accretions. Candidate porous panels were tested in the Ohio State University 6- x 12-inch transonic airfoil tunnel and result in essentially interference-free flow, as evidenced by pressure distributions over a NACA 0012 airfoil for Mach numbers up to 0.75. Application to the NRC 12- x 12-inch icing tunnel showed a similar result, which allowed proper transonic flow simulation in that tunnel over its full speed range.

Lee, J. D.↗
NASA NTRS1990

Preventing Ventilation On Sailboard Skegs

Design effort undertaken to solve spinout problem plaguing high-performance sailboards. Proposed skeg section designed by use of computer model of pressure field and boundary layer. Prevents ventilation by maintaining attached boundary-layer flow throughout operating environment. Cavitation also avoided by preventing valleys in pressure distribution while skeg operated throughout its range.

Caldwell, Richard A.↗
NASA NTRS1989

On the reverse flow ceiling jet in pool fire-ventilation crossflow interactions in a simulated aircraft cabin interior

The behavior of the reverse flow ceiling jet against the ventilation flow from 0.58 to 0.87 m/s was investigated in a 1/3 scale model of a wide body aircraft interior. For all tests, strong reverse-flow ceiling jets of hot gases were detected well upstream of the fire. Both thicknesses of the reverse-flow ceiling jet and the smoke layer increased with the fire-crossflow parameter. The thickness of the smoke layer where the smoke flows along the main flow below the reverse-flow ceiling jet was almost twice that of the reverse-flow ceiling jet. Detailed spatial and time-varying temperatures of the gas in the test section were measured, and velocity profiles were also measured using a temperature compensated hot film.

Kwack, E. Y.↗