Diffuser Efficiency and Flow Process of Supersonic Wind Tunnels with Free Jet Test Section

Diffuser Efficiency and Flow Process of Supersonic Wind Tunnels with Free Jet Test Section
Author: Rudolf Hermann
Publisher:
Total Pages: 90
Release: 1950
Genre: Wind tunnels
ISBN:

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.

High-speed Wind Tunnels

High-speed Wind Tunnels
Author: Luigi Crocco
Publisher:
Total Pages: 236
Release: 1946
Genre: Aerodynamics, Supersonic
ISBN:

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.

Comparison of Stagnation Pressure Control Systems for a 12-INCH Blowdown Transonic Tunnel

Comparison of Stagnation Pressure Control Systems for a 12-INCH Blowdown Transonic Tunnel
Author:
Publisher:
Total Pages:
Release: 1957
Genre:
ISBN:

Presented at the Eight Meeting of the Supersonic Wind- Tunnel Association, Seattle, Wash., Oct. 1957. The two control systems are compared for nominal stagnation pressures of 16 and 34 psia. The improved performance of system B has resulted in increased Mach number capability of the tunnel, improved Mach number control during a run, and an increase in the run frequency. (W.L.H.).

A Numerical Comparison of Symmetric and Asymmetric Supersonic Wind Tunnels

A Numerical Comparison of Symmetric and Asymmetric Supersonic Wind Tunnels
Author: Kylen D. Clark
Publisher:
Total Pages: 138
Release: 2015
Genre:
ISBN:

Supersonic wind tunnels are a vital aspect to the aerospace industry. Both the design and testing processes of different aerospace components often include and depend upon utilization of supersonic test facilities. Engine inlets, wing shapes, and body aerodynamics, to name a few, are aspects of aircraft that are frequently subjected to supersonic conditions in use, and thus often require supersonic wind tunnel testing. There is a need for reliable and repeatable supersonic test facilities in order to help create these vital components. The option of building and using asymmetric supersonic converging-diverging nozzles may be appealing due in part to lower construction costs. There is a need, however, to investigate the differences, if any, in the flow characteristics and performance of asymmetric type supersonic wind tunnels in comparison to symmetric due to the fact that asymmetric configurations of CD nozzle are not as common. A computational fluid dynamics (CFD) study has been conducted on an existing University of Michigan (UM) asymmetric supersonic wind tunnel geometry in order to study the effects of asymmetry on supersonic wind tunnel performance. Simulations were made on both the existing asymmetrical tunnel geometry and two axisymmetric reflections (of differing aspect ratio) of that original tunnel geometry. The Reynolds Averaged Navier Stokes equations are solved via NASA's OVERFLOW code to model flow through these configurations. In this way, information has been gleaned on the effects of asymmetry on supersonic wind tunnel performance. Shock boundary layer interactions are paid particular attention since the test section integrity is greatly dependent upon these interactions. Boundary layer and overall flow characteristics are studied. The RANS study presented in this document shows that the UM asymmetric wind tunnel/nozzle configuration is not as well suited to producing uniform test section flow as that of a symmetric configuration, specifically one that has been scaled to have equal aspect ratio. Comparisons of numerous parameters, such as flow angles, pressure (both static and stagnation), entropy, boundary layers and displacement thickness, vorticity, etc. paint a picture that shows the symmetric equal aspect ratio configuration to be decidedly better at producing desirable test section flow. It has been shown that virtually all parameters of interest are both more consistent and have lower deviation from ideal conditions for the symmetric equal area configuration.

A Comparison of Transition Reynolds Numbers from 12-in. and 40-in. Supersonic Tunnels

A Comparison of Transition Reynolds Numbers from 12-in. and 40-in. Supersonic Tunnels
Author: C. J. Schueler
Publisher:
Total Pages: 42
Release: 1963
Genre: Aerodynamics, Supersonic
ISBN:

Transition Reynolds number measurements on a hollow cylinder in the von Karman Gas Dynamics Facility's 12-inch and 40-inch supersonic tunnels show that the highest transition Reynolds numbers were obtained in the 40-inch tunnel, although the variations with unit Reynolds number were the same at Mach numbers 3 to 5. The influence of nose bluntness in the 40-inch tunnel corresponds closely with the results obtained in the 12-inch tunnel.

Simulation of Pressure and Temperature Responses for the 20 Inch Supersonic Wind Tunnel

Simulation of Pressure and Temperature Responses for the 20 Inch Supersonic Wind Tunnel
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
Total Pages: 56
Release: 2018-07-10
Genre:
ISBN: 9781722739270

A simulation of the pressure and temperature responses of the 20 inch Supersonic Wind Tunnel (SWT) is developed. The simulation models the tunnel system as a set of lumped parameter volumes connected by flow regulating elements such as valves and nozzles. Simulated transient responses of temperature and pressure for the five boundary points of the 20 inch SWT operating map are produced from their respective initial conditions, tunnel operating conditions, heater input power, and valve positions. Upon reaching steady state, a linearized model for each operating point is determined. Both simulated and actual tunnel responses are presented for comparison. Motter, Mark A. Langley Research Center...