Browsing by Author "Huang, Kun-Rong"

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An investigation of natural convection in a three dimensional square wavy channel
(2015-08-01)
Fu, Wu-Shung
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Huang, Kun-Rong
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Lo, Chi-Xiu
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Wang, Wei-Hsiang
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機械工程學系
Natural convection in a three dimensional wavy channel, which is composed of numerous two dimensional cross sections, is investigated numerically. The method of elliptic partial differential equations grid generation is adopted to construct a distribution of grids on each cross section. The distributions of the whole cross sections are piled up in sequence from the inlet to outlet to form a three dimensional channel. In order to solve a low speed compressible flow problem, the compressibility and viscosity of the working fluid are taken into consideration, and the non-reflecting boundaries at the inlet and outlet of the channel are held. The Bossinesq assumption is then no longer necessary. As well, the methods of the Roe scheme, preconditioning and dual time stepping matching the implicit LUSGS algorithm (Implicit Lower Upper symmetric Gauss-Seidel algorithm) are simultaneously used to solve governing equations. Effects of the Rayleigh number and the ratio of the amplitude to wave length on heat transfer rates of the channel are examined. Results of both this study and existing studies have good agreements. (C) 2015 Elsevier Ltd. All rights reserved.
Applying Compute Unified Device Architecture to Investigate Gaseous Discharge from High-Pressure Vessel
(2016-01)
Fu, Wu-Shung
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Huang, Kun-Rong
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Wang, Wei-Hsiang
;
Li, Chung-Gang
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機械工程學系
The aim of this study is to investigate gases discharged from a high-pressure vessel numerically. To simulate this subject more realistically, the viscosity and compressibility of the gas are taken into consideration simultaneously. The methods of the Roe scheme, preconditioning, and dual time-stepping matching the lower-upper symmetric-Gauss-Seidel method are adopted to solve compressible flow problems during gaseous discharge processes. The nonreflecting boundary condition is used to prevent flowfields from being polluted by the reflection of the pressure wave induced by the compressible flow at the boundary. Computing procedures are performed on the compute unified device architecture computation platform, which was recently developed and is a highly effective technology for accelerating computational speed. Results show that the mass flow rate of this work is consistent with the existing experimental work. Because of a sudden expansion at a small opening, the phenomena of an alternating variation of the pressures of gases, rapid decrements of the temperature of gases, and a quick acceleration of the velocities of gases are remarkably observed in the mainstream direction. The ratio of the thrust caused by the gases released to the reaction force is less than 1 because of the dissipation of entropy generation.