A Study of the Simulation of Flow with Free-stream Mach Number 1 in a Choked Wind Tunnel

A Study of the Simulation of Flow with Free-stream Mach Number 1 in a Choked Wind Tunnel
Author: John R. Spreiter
Publisher:
Total Pages: 44
Release: 1960
Genre: Aerodynamics
ISBN:

Summary: The degree to which experimental results obtained under choking conditions in a wind tunnel with solid walls simulate those associated with an unbounded flow with free-stream Mach number 1 is investigated for the cases of two-dimensional and axisymmetric flows. It is found that a close resemblance does indeed exist in the vicinity of the body, and that the results obtained in this way are generally at least as accurate as those obtained in a transonic wind tunnel with partly open test section. Some of the results indicate, however, that substantial interference effects, particularly those of the wave reflection type, may be encountered under certain conditions, both in choked wind tunnels and in transonic wind tunnels, and that the reduction of these interference effects to acceptable limits may require the use of models of unusually small size.

Theoretical Pressure Distributions on Wings of Finite Span at Zero Incidence for Mach Numbers Near 1

Theoretical Pressure Distributions on Wings of Finite Span at Zero Incidence for Mach Numbers Near 1
Author: Alberta Y. Alksne
Publisher:
Total Pages: 58
Release: 1961
Genre: Aerodynamics, Transonic
ISBN:

A method employed heretofore by the authors to obtain approximate solutions of the transonic flow equation for plane and axisymmetric flow is extended to give reasonable results for wings of finite span, consistent with the known properties of transonic flows. In this method the partial differential equation appropriate to the study of transonic flow is replaced by a nonlinear ordinary differential equation which can be solved by numerical methods. Asymptotic forms of this differential equation are given for very high and very low aspect ratios and analytic results are obtained for certain special cases. Numerical results, calculated by use of electronic computing machines, are given in the form of pressure distribution and pressure drag for two profile shapes, wedge and circular arc, for wings of rectangular plan form. The range of aspect ratios covered extends effectively from zero to infinity and agreement with the asymptotic results is shown at both limits.