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Author: Milton M. Klein
Publisher:
ISBN:
Category : Atmospheric temperature
Languages : en
Pages : 48
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Book Description
The classic theory of buoyant motion of a free planar heated jet in still air is extended to account for environmental winds from the same direction as the jet, that is, co-flowing winds. The model is applicable for wind and jet velocities up to 100 m/sec, and jet temperatures up to three times the ambient. Calculations are made for initial jet velocities of 5 and 20 m/sec and temperature excesses, relative to ambient temperature, of 0.3 and 1. For light winds relative to the initial jet velocity the vertical velocity and centerline trajectory of the plume rise rapidly with distance from the jet source. This is similar to that found with the classic theory for still air. As the wind speed approaches the initial jet velocity, the rise of the jet plume with distance from the source is much more gradual. For all wind speeds, the axial jet velocity and temperature decrease rapidly with distance from the jet source, until they become almost constant at short distances downstream. A similarity rule is derived which preserves dynamic similarity in scaling from a given system to another system. For low wind speeds the procedure is close to that based on constant Froude number. (Author).
Author: Milton M. Klein
Publisher:
ISBN:
Category : Atmospheric temperature
Languages : en
Pages : 48
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Book Description
The classic theory of buoyant motion of a free planar heated jet in still air is extended to account for environmental winds from the same direction as the jet, that is, co-flowing winds. The model is applicable for wind and jet velocities up to 100 m/sec, and jet temperatures up to three times the ambient. Calculations are made for initial jet velocities of 5 and 20 m/sec and temperature excesses, relative to ambient temperature, of 0.3 and 1. For light winds relative to the initial jet velocity the vertical velocity and centerline trajectory of the plume rise rapidly with distance from the jet source. This is similar to that found with the classic theory for still air. As the wind speed approaches the initial jet velocity, the rise of the jet plume with distance from the source is much more gradual. For all wind speeds, the axial jet velocity and temperature decrease rapidly with distance from the jet source, until they become almost constant at short distances downstream. A similarity rule is derived which preserves dynamic similarity in scaling from a given system to another system. For low wind speeds the procedure is close to that based on constant Froude number. (Author).
Author: Milton M. Klein
Publisher:
ISBN:
Category : Atmospheric temperature
Languages : en
Pages : 44
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Book Description
A broad effort is being conducted to develop an operational Warm Fog Dispersal System (WFDS) using ground-based heat sources. In order to determine the optimum heat and thrust for the combustors in the WFDS, investigations have been made of the buoyant motion in round- and plane-heated turbulent jets in co-flowing (that is, same direction) wind fields. This report describes a method of calculating the round jet case. The method can be used for jet velocities of 100m/sec or less, wind velocities below or equal to the jet velocity, and jet temperatures up to 3 times the ambient value. Initial jet velocities of 5 and 20m/sec and temperature excesses, relative to the ambient temperature, of .3 and 1 were selected for the calculations.
Author: Milton M. Klein
Publisher:
ISBN:
Category : Aerothermodynamics
Languages : en
Pages : 36
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Book Description
Experimental and theoretical programs are being conducted to aid in the development of an operational warm fog dispersal system using momentum-driven ground-based heat sources. In previous investigations, the wind was in the same direction as the jet (coflowing). The present investigation is concerned with a jet opposite in direction to the ambient wind (counterflowing or opposing jet). A model for calculating the dynamic characteristics of a cold counter-flowing jet has been extended to take account of the effect of heating upon the jet. The effect of buoyancy upon the motion of the jet will be presented in a subsequent report.
Author: Milton M. Klein
Publisher:
ISBN:
Category : Fog
Languages : en
Pages : 40
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Book Description
A broad experimental and theoretical program is being conducted to aid in the development of an operational warm fog dispersal system which utilizes momentum driven ground based heat sources. To help determine optimum heat and thrust combinations for the system, investigations are being made of the buoyant motion of heated turbulent jets both coflowing (wind and jet in the same direction) and counterflowing (wind and jet opposite). The investigation of the coflowing jet has been completed and in addition a model has been developed from which the dynamic characteristics of a heated counterflowing jet in the absence of buoyancy can be calculated. The present investigation is concerned with the effect of buoyancy upon the motion of a counterflowing jet. The lower portion of the trajectory, which has been calculated by the present model, is in fair to good agreement with the corresponding experimental curve, the calculated curve tending to be somewhat higher than that obtained experimentally. The calculated upper part of the trajectory, obtained from a model which gives the deflection of a jet in a crosswind, is in good agreement with experiment.
Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 1460
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Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author:
Publisher:
ISBN:
Category : Geophysics
Languages : en
Pages : 44
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Book Description
Author: Bruce A. Kunkel
Publisher:
ISBN:
Category : Fog
Languages : en
Pages : 48
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Book Description
Field tests were conducted with a subscale momentum/heat system, to determine the optimum heat and thrust requirements and combustor positions for a full scale thermal fog dispersal system. The site, located in Irvine, California, was laid out on a 1/6 scale. The Froude number scaling law was used to scale up to full scale. An array of 65 thermistors and 6 wind sensors was located in the target area over a simulated runway. Wind and temperature sensors were also located outside of the target area to provide background measurements during the tests. Tests were conducted at night, in clear air, during calm conditions. Both momentum and passive heat systems are evaluated in terms of heat and thrust requirements for different wind conditions. A single line momentum/heat system requires 5 to 10 times as much thrust as does a two-side-of-the-runway system. A passive system requires anywhere from 130-470 percent more heat output than does a momentum system. The appropriate system for a particular airfield can only be determined after a cost analysis has been made of the various systems and a wind study has been made of the particular airfield.
Author: Milton M. Klein
Publisher:
ISBN:
Category : Fog
Languages : en
Pages : 28
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Book Description
Experimental and theoretical programs are being conducted to aid in the development of an operational Warm Fog Dispersal System using ground based heat sources. To help determine optimum heat and thrust combinations for the system, investigations have been made of the buoyant motion of heated turbulent jets in co-flowing; that is, same direction ambient winds. To take account of the ground effect, an analysis has been made of the experimental data for the planar jet at the point of lift-off in terms of the local Froude number at this point. From this correlation a procedure has been developed for determining the lift-off point, using the ambient wind and initial velocity and temperature of the jet as input variables. A new jet trajectory may now be easily calculated with only a simple modification of the original method in which the ground effect was ignored.
Author: Technology Reports Centre (Great Britain)
Publisher:
ISBN:
Category :
Languages : en
Pages : 536
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Author: Air Force Cambridge Research Laboratories (U.S.)
Publisher:
ISBN:
Category : Geophysics
Languages : en
Pages : 228
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