The Calculation of Wall Shearing Stress from Heat-Transfer Measurements in Compressible Flows

1954 ◽  
Vol 21 (3) ◽  
pp. 201-202 ◽  
Author(s):  
Nick S. Diaconis
Keyword(s):  
Heat Transfer ◽  
Compressible Flows ◽  
Shearing Stress ◽  
Wall Shearing Stress

A Numerical Study of the Thermal Performance of Two Stationary Insert Designs in Internal Compressible Flows

2009 ◽  
Author(s):  
Emad Y. Tanbour ◽  
Ramin K. Rahmani
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Forced Convection ◽  
Thermal Performance ◽  
Compressible Flows ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Transfer Enhancement ◽  
Stationary Heat Transfer

Enhancement of the natural and forced convection heat transfer has been the subject of numerous academic and industrial studies. Air blenders, mechanical agitators, and static mixers have been developed to increase the forced convection heat transfer rate in compressible and incompressible flows. Stationary inserts can be efficiently employed as heat transfer enhancement devices in the natural convection systems. Generally, a stationary heat transfer enhancement insert consists of a number of equal motionless segments, placed inside of a pipe in order to control flowing fluid streams. These devices have low maintenance and operating costs, low space requirements and no moving parts. A range of designs exists for a wide range of specific applications. The shape of the elements determines the character of the fluid motion and thus determines thermal effectiveness of the insert. There are several key parameters that may be considered in the design procedure of a heat transfer enhancement insert, which lead to significant differences in the performance of various designs. An ideal insert, for natural conventional heat transfer in compressible flow applications, provides a higher rate of heat transfer and a thermally homogenous fluid with minimized pressure drop and required space. To choose an insert for a given application or in order to design a new insert, besides experimentation, it is possible to use Computational Fluid Dynamics to study the insert performance. This paper presents the outcomes of the numerical studies on industrial stationary heat transfer enhancement inserts and illustrates how a heat transfer enhancement insert can improve the heat transfer in buoyancy driven compressible flows. Using different measuring tools, thermal performance of two different inserts (twisted and helix) are studied. It is shown that the helix design leads to a higher rate of heat transfer, while causes a lower pressure drop in the flowfield, suggesting the insert effectiveness is higher for the helix design, compared to a twisted plate.

Computational Analysis of Conjugate Heat Transfer in Gaseous Micro Channels

2013 ◽  
Author(s):  
Giulio Croce ◽  
Olga Rovenskaya ◽  
Paola D’Agaro
Keyword(s):  
Heat Transfer ◽  
Compressible Flows ◽  
Conjugate Heat Transfer ◽  
Computational Analysis ◽  
Slip Flow ◽  
Heat Transfer Analysis ◽  
Navier Stokes ◽  
Jump Model ◽  
Micro Channels ◽  
Slip Flow Regime

A fully conjugate heat transfer analysis of gaseous flow, within slip flow regime, in short microchannel is presented. A Navier Stokes code, coupled with Maxwell and Smoluchowski slip and temperature jump model, is adopted. Due to the link between temperature and velocity field in highly compressible flows, results are presented for Nusselt number, heat sink thermal resistance and resulting wall temperature as well as Mach number profiles for different conditions, commenting on the relative importance of wall conduction, rarefaction and compressibility. Compressibility plays a major role, and the reduction in heat transfer rate due to axial conduction is quite remarkable.

Plane Turbulent Wall Jet Flow Development and Friction Factor

1963 ◽  
Vol 85 (1) ◽  
pp. 47-53 ◽  
Author(s):  
G. E. Myers ◽  
J. J. Schauer ◽  
R. H. Eustis
Keyword(s):  
Maximum Velocity ◽  
Velocity Profiles ◽  
Wall Jet ◽  
Shearing Stress ◽  
Integral Methods ◽  
Velocity Decay ◽  
Wall Jet Flow ◽  
Turbulent Wall ◽  
Momentum Integral ◽  
Wall Shearing Stress

An investigation of the jet development, the velocity profiles, and the wall shearing stress in a two-dimensional, incompressible, turbulent wall jet was undertaken. The maximum velocity decay, jet thickness, and the shearing stress are predicted analytically by momentum-integral methods. Experimental data concerning velocity profiles, velocity decay, and jet thickness agree well with previous investigators. The wall shearing stress was measured by a hot-film technique and the results help to resolve a wide divergence between the experimental values of other investigators.

Conjugate Heat Transfer Analysis of NASA C3X Film Cooled Vane With an Object-Oriented CFD Code

2010 ◽  
Author(s):  
Luca Mangani ◽  
Matteo Cerutti ◽  
Massimiliano Maritano ◽  
Martin Spel
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Compressible Flows ◽  
Conjugate Heat Transfer ◽  
Operating Conditions ◽  
Heat Transfer Analysis ◽  
Special Treatment ◽  
Cross Sectional ◽  
Optimal Position ◽  
Grid Interface

This paper presents the developments done on a CFD unstructured solver, based on the OpenFOAM® CFD libraries, to perform conjugate heat transfer simulations in turbomachinery applications. The solver uses a SIMPLE-C All-Mach algorithm with a special treatment for the pressure corrector equation to deal with highly compressible flows. Moreover, the solver provides an exhaustive turbulence model library, specific for heat transfer calculations and an implicit treatment for fluid-to-fluid and solid-to-fluid boundaries using a generic grid interface (GGI) that allows a greater mesh generation flexibility. The development of the generic grid interface is described in the current paper. The conjugate numerical methodology was employed to predict the metal temperature of a three-dimensional first stage gas turbine blade at realistic operating conditions. The validation case is based on the 1988 NASA C3X experimental setup of a internally and film cooled vane. The stator vane was internally cooled by an array of radial cooling channels of constant cross-sectional area an externally by rows of film cooling holes. The mesh has been generated with GridPRO®, using a multi block structured approach. The optimization methods used in the grid generator provide a full hex grid maintaining mesh orthogonality at the walls and within the domain and allowing the nodes to be moved to an optimal position. Numerical and experimental results are compared in terms of pressure and temperature distribution on the blade wall at mid-span, as well as heat transfer coefficient profiles.

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