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C. B. Johnson

Bio: C. B. Johnson is an academic researcher from Langley Research Center. The author has contributed to research in topics: Boundary layer & Aerodynamic heating. The author has an hindex of 1, co-authored 1 publications receiving 11 citations.

Papers
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01 Sep 1974
TL;DR: In this article, an experimental investigation of interference heating resulting from interactions of shock waves and turbulent boundary layers was conducted, where pressure and heat-transfer distributions were measured on a flat plate in the free stream and on the wall of the test section of the Langley Mach 6 high Reynolds number tunnel for Reynolds numbers ranging from 2 million to 400 million.
Abstract: An experimental investigation of interference heating resulting from interactions of shock waves and turbulent boundary layers was conducted. Pressure and heat-transfer distributions were measured on a flat plate in the free stream and on the wall of the test section of the Langley Mach 6 high Reynolds number tunnel for Reynolds numbers ranging from 2 million to 400 million. Various incident shock strengths were obtained by varying a wedge-shock generator angle (from 10 deg to 15 deg) and by placing a spherical-shock generator at different vertical positions above the instrumented flat plate and tunnel wall. The largest heating-rate amplification factors obtained for completely turbulent boundary layers were 22.1 for the flat plate and 11.6 for the tunnel wall experiments. Maximum heating correlated with peak pressures using a power law with a 0.85 exponent. Measured pressure distributions were compared with those calculated using turbulent free-interaction pressure rise theories, and separation lengths were compared with values calculated by using different methods.

11 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the principles of the fluorescent paint technique for surface heat transfer measurement are presented, and the temperature sensitive paint is used to visualize and measure heat transfer in several typical shock-turbulent boundary layer interactions.

42 citations

Journal ArticleDOI
TL;DR: In this paper, a nouvelle methode de mesure du taux de transfert de chaleur aux flux thermiques fluctuants dans les regions d'interaction d'ondes de choc incidentes obliques and de couches limites turbulentes is presented.
Abstract: On applique une nouvelle methode de mesure du taux de transfert de chaleur aux flux thermiques fluctuants dans les regions d'interaction d'ondes de choc incidentes obliques et de couches limites turbulentes

37 citations

01 Jan 1986
TL;DR: In this paper, a thin film heat transfer gauge is applied to the measurement of heat transfer coefficients in the interaction regions of incident shock waves and fully developed turbulent boundary layers, and experiments were performed under the conditions of Mach number = 4, total pressure = 1.2 MPa, 0.59 to approximately 0.65, and incident shock angles from 17.8 to 22.8 degrees.
Abstract: A thin film heat transfer gauge is applied to the measurement of heat transfer coefficients in the interaction regions of incident shock waves and fully developed turbulent boundary layers. It was developed to measure heat flux with high spatial resolution and fast response for wind tunnels with long flow duration. To measure the heat transfer coefficients in the interaction region in detail, experiments were performed under the conditions of Mach number = 4, total pressure = 1.2 MPa, 0.59 to approximately 0.65. Reynolds number = 1.3 to approximately 1.5 x 10 to the 7th power and incident shock angles from 17.8 to 22.8 degrees. The results show that the heat transfer coefficient changes complicatedly in the interaction region. At the beginning the interaction region, the heat transfer coefficient decreases at first, reaches its minimum value at the point where the pressure begins to increase, and then increases sharply. When the boundary layer begins to separate, even a small separation bubble causes significant changes in the heat transfer coefficient, while the pressure does not show any changes which suggests that the boundary layer begins to separate.

17 citations

Journal ArticleDOI
TL;DR: In this paper, a simple method is developed to predict heating to a flat plate surface influenced by an impinging shock wave emanating from a two-dimensional wedge, where the freestream flow conditions and shock generator wedge angle are specified, peak heating values can be computed for either laminar or turbulent oncoming flow.
Abstract: A simple method is developed to predict heating to a flat plate surface influenced by an impinging shock wave emanating from a two-dimensional wedge. Once the freestream flow conditions and shock generator wedge angle are specified, peak heating values can be computed for either laminar or turbulent oncoming flow. Flow that is init ial ly laminar can either remain laminar or be tripped to transitional or turbulent flow by the impinging shock wave. A transition Reynolds number for flow perturbed by the impinging shock wave is also derived from heating correlations. Finally, the study results indicate that the extremely large increases in interference heating over the undisturbed flat plate values are partially due to boundary-layer transition caused by the impinging shock wave. Experimental data obtained from simple geometry wedge/flat plate models as well as recent results from Space Shuttle models are used in this analysis.

15 citations

01 Nov 1974
TL;DR: An integral method for predicting boundary layer development in turbulent flow regions on two-dimensional or axisymmetric bodies was developed in this paper, which has the capability of approximating nonequilibrium velocity profiles as well as the local surface friction in the presence of a pressure gradient.
Abstract: An integral method for predicting boundary layer development in turbulent flow regions on two-dimensional or axisymmetric bodies was developed. The method has the capability of approximating nonequilibrium velocity profiles as well as the local surface friction in the presence of a pressure gradient. An approach was developed for the problem of predicting the heat transfer in a turbulent boundary layer in the presence of a high pressure gradient. The solution was derived with particular emphasis on its applicability to supersonic combustion; thus, the effects of real gas flows were included. The resulting integrodifferential boundary layer method permits the estimation of cooling reguirements for scramjet engines. Theoretical heat transfer results are compared with experimental combustor and noncombustor heat transfer data. The heat transfer method was used in the development of engine design concepts which will produce an engine with reduced cooling requirements. The Langley scramjet engine module was designed by utilizing these design concepts and this engine design is discussed along with its corresponding cooling requirements. The heat transfer method was also used to develop a combustor cooling correlation for a combustor whose local properties are computed one dimensionally by assuming a linear area variation and a given heat release schedule.

15 citations