摘要:

A finite volume numerical model, using a nonorthogonal adaptive grid, has been developed to examine both steady deformed and transient deforming droplet behavior. The model has been tested by comparison with existing numerical solutions and experimental data. Computations of the steady state evaporation of n-heptane droplets in high-temperature air (T*∞= 1000 K, 10 ≤ Re∞≤ 100, We∞≤ 10) show deformed oblate shapes with major axes perpendicular to the mean flow direction. Using volume equivalent diameters, predictions based on existing Nusselt and Sherwood number correlations for spherical droplets are in good agreement with the numerical results. A new correlation is presented for the drag coefficient of deformed vaporizing droplets.

ISSN:1040-7782    

DOI:10.1080/10407789408955991

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

To help resolve the inconsistencies observed when examining measured properties of free plane jets and plumes, a numerical study was performed to determine the influence of a weak ambient motion and of the associated pressure field on the flows of free plane vertical turbulent jets and plumes. A nested grid control volume technique with the buoyancy-extended k-e model plane was used to model turbulent jets and plumes issuing into open spaces as veil as into two-dimensional rooms of various sizes. The results indicate that slight variations in the ambient pressure distribution affect jet and plume development and similarity relationships.

ISSN:1040-7782    

DOI:10.1080/10407789408955992

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Findings that maximize output performance of three-phase spray columns show that dramatic increases in total heat transfer can be achieved. Results from simulations are presented that show when the dispersed fluid is introduced into the exchanger at or near its saturation temperature, increases of approximately a half order of magnitude are possible. In some cases, reversals in previously reported trends are found when direct-contact heat exchanger operating limits are expanded, shedding new tight on possible optimization of direct-contact heat exchanger design and output.

ISSN:1040-7782    

DOI:10.1080/10407789408955993

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An artificial compressibility method for solving the incompressible Navier-Stokes equations has been applied to the study of flow past a circular cylinder with and without flow control devices. The Reynolds number ranges from 46 to 200. The numerical method is based on upwind finite volume methods for space discretizations and an explicit Runge-Kutta time integration with implicit residual smoothing methods for time discretizations. Two kinds of flow control devices are investigated: (1) placing an attached or a detached splitter plate and (2) placing a second small cylinder (control cylinder) behind a circular cylinder. Numerical investigations show that both are effective in the suppression of vortex shedding and the reduction of drag.

ISSN:1040-7782    

DOI:10.1080/10407789408955994

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A numerical study is performed to investigate heat transfer and fluid flow in the entrance and fully developed regions of an annulus, consisting of a rotating, insulated inner cylinder and a stationary, heated outer cylinder. Several different k-ϵ turbulence models are employed to determine the turbulent kinetic energy, its dissipation rate, and the heat transfer performance. The governing boundary layer equations are discretized by means of a control volume finite difference technique and numerically solved using the marching procedure. In the entrance region the axial rotation of the inner cylinder induces a thermal development and causes an increase in both the Nusselt number and the turbulent kinetic energy in the inner cylinder wall region. In the fully developed region, an increase in the Taylor number causes an amplification of the turbulent kinetic energy over the whole cross section, resulting in a substantial enhancement in the Nusselt number. These transport phenomena are also affected by the radius ratio and Reynolds number.

ISSN:1040-7782    

DOI:10.1080/10407789408955995

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The finite element method was used to solve Luikov's system of partial differential equations for neat, mass, and pressure transfer in capillary porous bodies. The finite element predictions were validated by comparing with exact solutions and the analytical results given by Mikhailov and Shishedjiev [1]. An application of the finite element method to the drying of wood (spruce) and a comparison based on an eigenvalue solution for simultaneous heat and mass transfer [2] are also provided. This technique was applied to study the coupled transport process in a silicon gel. The simulation indicated that the results obtained from the heat, mass, and pressure transfer model showed a marked difference from the results obtained by the heat and mass transfer model.

ISSN:1040-7782    

DOI:10.1080/10407789408955996

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A numerical method for determination of slotted-fin efficiency is presented. The control volume based finite difference method was applied to obtain the temperature distribution of the slotted fin. The effects of the slots on the temperature distribution over the fin surface were taken into account by application of the additional source term method. Computations were conducted for four configurations of the slotted fins. It is found that under the same conditions, the efficiency of the slotted fin is always lower (typically by 5-15%) than that of the nonslotted fin. Efficiency curves of the four slotted fins are presented, and the factors that affect slotted-fin efficiency are discussed.

ISSN:1040-7782    

DOI:10.1080/10407789408955997

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Finite difference calculations were carried out for natural convection in a fluid of low Prandtl number between isothermal, horizontal plates with the higher temperature on the plate below. The motion was postulated to consist of two-dimensional roll cells with a width equal to their height. The computations encompassed Prandtl numbers from 10−4to 0.72 and Rayleigh numbers from the critical value for the onset of motion up to 3000. They were repeated for three to six different grid sizes in order to permit accurate extrapolation of Nu —1 to zero grid size. The computed value of the critical Ra for all values of Pr agreed closely with the theoretical value of 1709. The computed values of Nu for Ra greater than the critical value agreed closely with the prior results of Clever and Basse obtained by the Galerkin method. A correlating equation was derived to represent the new results.

ISSN:1040-7782    

DOI:10.1080/10407789408955998

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor