摘要:

Turbulent flow of supercritical hydrogen through a uniformly healed circular tube has been investigated using numerical methods, for the range of 4 × 105 ≤ Re ≤ 3 × 106, 5 ≤ qw ≤ 10 MW/m2, 30 ≤ Tin ≤ 90 K, and 5 ≤ Pin ≤ 15 MPa. The purpose is to validate a turbulence model and calculation method for the design of active cooling systems of hydrogen-fueled hypersonic aircraft, when the hydrogen fuel is used as coolant. The PHOENICS software package was used for the computations, which required special provision for evaluation of the thermophysical properties of the supercritical hydrogen, and a low Reynolds number form of the k-e turbulence model. Pressure drop and heat transfer data were compared with experiment and existing correlations, and good agreement was demonstrated. For the pressure range considered here a “thermal spike” was observed and shown to be due to the secondary peak in specific heat, rather than the primary peak.

ISSN:1040-7782    

DOI:10.1080/10407789308902600

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A new integral one-step reaction submodel has been developed for an Argonne combustion computer code to simulate reacting flows of an advanced combustor for magnetohydrody-narmic power generation. The integral combustion code makes numerical calculations of a reacting flow more efficient and mart stable while still preserving the major physical effects of the complex combustion processes. Results of the simulation indicate that (1) fluid mixing is mainly responsible for combustion performance and (2) counterflow injection with an injection angle in the range of 120°to 140°yields the best mixing and combustion performance.

ISSN:1040-7782    

DOI:10.1080/10407789308902601

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The present work considers the numerical modeling of turbulent flow in rotating cavities with a radial imposed flux and a preliminary examination of heat transfer prediction. Two turbulence models are studied: the standard k– ∈ low–Reynolds–number approach and a zonal approach using second–order algebraic stress model in the core region adapted to rotating flows. The computational procedure is based on a finite volume method. Predictions are compared with experimental data in the literature. The results bring to light the importance of a detailed near–wall treatment in order to properly capture the Ekman layer region. Second–order modeling seems to be necessary to attain a wider practical value, particularly in the presence of recirculation zones and three–dimensional effects in strong rotation.

ISSN:1040-7782    

DOI:10.1080/10407789308902602

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

An analysis is made of the laminar natural convection in two internally finned horizontal annuli. The governing equations were solved numerically by a control-volume-based finite difference method. Information about the flow patterns and temperature distributions is presented through velocity vectors, streamlines, and isotherm plots. The effects of Rayl1eigh number and fin height on the Nusselt numbers are presented for two selected fin orientations. Variations of the local Nusselt numbers along the inner cylinder are also presented. In the cases studied, orientations of the internal fins are found to have insignificant effects on the average Nusselt number.

ISSN:1040-7782    

DOI:10.1080/10407789308902603

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

This paper presents the simulation of heat transfer and flow patterns in an enclosure between two isothermal concentric cylinders of rhombic cross sections. Four different values of the enclosure gap (Eg = 0.875, 0.75, 0.5, and 0.25) and three different rhombic angles (Ω = 10°, 20°, and 30°) are considered. At low Rayleigh numbers (103-105) the flow is weak and conduction is the dominant mode of heat transfer. Convection plays a key role starting at higher Rayleigh numbers (106-107). For all cases studied, there is no tendency for flow separation at the horizontal corners. The flow strength is found to increase with increasing rhomsic angel, increasing enclosure gap, and increasing Rayleigh number. The critical Rayleigh number at which the heat transper is influenced by convention decreases with ihcreasing gap values and increasing rhombic angle; it is as high as 106-107for Eg = 0.25 and decreases to about 104for Eg = 0.875.

ISSN:1040-7782    

DOI:10.1080/10407789308902604

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A numerical study is carried out on mixed convection heat transfer (laminar natural and forced convections) in inclined open ended channels. The isothermal discrete heating elements are equally distanced and placed on one side, while isothermal conditions are imposed on the other. The governing equations are solved using the finite difference method. Normalized average and local Nusselt numbers are calculated as functions of the Rayleigh number (103 ≤ Ra ≤ 105), Reynolds number (10 ≤ Re ≤ 50), inclination angle (0 ≤ 0 ≤ 90), various heat sources (0.1 ≤ A ≤ 1), and various aspect ratios (5 ≤ B ≤ 20). These include, as limiting cases, horizontal and vertical positions. Flow and temperature fields for various cases are also produced.

ISSN:1040-7782    

DOI:10.1080/10407789308902605

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor