Diffuser Efficiency of Free Jet Supersonic Wind Tunnels at Variable Test Chamber Pressure PDF Download

Author: Rudolf Hermann
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Rudolf Hermann
Publisher:
ISBN:
Category : Wind tunnels
Languages : en
Pages : 90

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Book Description
In the wind tunnel arrangement under consideration, the air leaves the Laval nozzle as a free jet and is recaptured by the diffuser, which is of the convergent-divergent design. A theoretical analysis of the flow process through this type of supersonic wind tunnel is presented and the diffuser efficiency is calculated for the case of equilibrium between test chamber pressure and pressure in the nozzle exit, assuming one-dimensional, in viscous, steady flow. Using the basic equations of continuity, energy and momentum flux through a bounding surface, an exact solution of the problem is obtained, which is applicable up to Mach number infinite. One of the basic results is, that in the recapturing zone of the diffuser a transition occurs from supersonic to subsonic flow, which is followed by an acceleration in the convergent portion up to sonic velocity at the second throat. The transition is not a normal shock and involves a total pressure loss greater than that of a normal shock at the test section Mach number. A mathematical solution with supersonic velocity after the transition process has no physical existence. A comprehensive comparison of the analytical results with available experiments in supersonic wind tunnels up to Mach number 4.4 regarding diffuser efficiency and second throat area shows good agreement.

Author: Klaus Oswatitsch
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ISBN:
Category : Diffusers
Languages : en
Pages : 30

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Author: Luigi Crocco
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ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 236

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The importance assumed in recent times by experimental supersonic wind tunnels, as well as the power required, has brought about the need for a study which would permit a comparison of the types tested and the principal theoretical plans.

Author:
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Category : Aeronautics, Military
Languages : en
Pages : 804

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Author: Warren H. Curry
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Category :
Languages : en
Pages : 160

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Author:
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ISBN:
Category :
Languages : en
Pages : 37

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A diffuser of variable geometric shape was tested for pressure recovery at M = 1.9, 2.5, 2.8, and 4.9 in the continuous 18- x 18-cm Aerophysics tunnel no. 3. The diffuser consisted of a converging-diverging, 2-dimensional, variable-area duct. The opening of the diffuser throat and the location of the throat along the center line of the duct were varied systematically. The effect of closed or half-open test section on diffuser efficiency and that of a model in the air stream were investigated. Operating and starting pressure ratios of the wind tunnel were determined, and performance data of the diffuser are given for both cases. Pressure recoveries of the operating tunnel were obtained for optimum diffuser configuration with diffuser end-pressure ranging up to 1.8 times pitot pressure in the test section at M = 4.9. Also lower pressure ratios to start the tunnel than previously known were found. Using this diffuser, a continuous tunnel can be operated with less power, or an intermittent tunnel can run for a longer time, and they can be started with a smaller (closer to one) over-all pressure ratio. The pressure recoveries obtained in a half-open test section and with models in the stream are somewhat lower, but the performance of the diffuser is not seriously offset by those modifications.

Author: Rudolf Hermann
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 412

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Author:
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Category : Aeronautics
Languages : en
Pages : 910

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Author: Ernest Darrell Kennedy
Publisher:
ISBN:
Category :
Languages : en
Pages : 126

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