Chang-Hsien Tai

Investigation of the thermo-flowfield in an underground concentrating solar tower

The main of this study investigated the optimal design in an underground concentrating solar tower. The underground concentrating system is a hemispheric shell which setup under the ground. It is coved by the glasses on the top on the ground surface, and this system can let the sunshine incident and induce the greenhouse to raise the ground surface temperature. There is a wind turbine mounted in the tower that is operated by the nature convection due to the effect of solar radiation in the tower. The present study applied the finite volume method, pressure-based algorithms, and coupled with P-1 radiation model to simulate and solve the anisentropic scattering problems. The results show that there is 5 degree lower with N2o adding than the air filled. The underground part is a greenhouse filled by N2o, and it can absorb infrared to raise the ground temperature.

Numerical studies of the flowfield over a hybrid VAWT with different torque

The study was a simulation of the organization of the axial wind turbines, the resistance type and three-piece lift-type structure, resistance type is semi-circular arc type, lift type of blade were NACA0018 airfoil and NACA4412, the inflow and rotational flow interactions. CFD computational fluid dynamics methods using finite volume method to solve Navier-Stokes equations to SIMPLE algorithms for incompressible flow, coupled with second-order upwind and dependency by testing the grid with the grid and the analytical characteristics of the turbulent flow pattern transition, And the other with sliding mesh method, and the additional number of dynamic flow rate of angular momentum, CFD simulation, the resistance type and NACA0018 and NACA4412 torque output, the more complex the fan if installed NACA0018 and NACA4412 additional vertical axis wind turbine will also improve the two Species of the wing part of the export value of the reverse. Only the resistance-type than the original state of the torque output value can be 3.6 times higher.

Numerical study of Transient Flow in a Full-Size Reflected Shock Tunnel

The aim of this paper is to develop a CFD solver that used to simulate the transient flow phenomena in a reflected shock tunnel. The transient flow phenomena in a shock tunnel include the reflected shock/boundary layer interaction and the starting process of nozzle flow that can affect the duration of test flow in actual conditions. To numerically simulate these transient flow features, a full-size, axisymmetric reflected shock tunnel model is used. The governing equations are a full Navier-Stokes equation, a species equation and a simplified polynomial correlation to simulate the real gas effects. The numerical code is developed based on the finite volume method coupled with the upwind Roes scheme and the total variation diminishing (TVD) method. To increase the calculation efficiency, a multi-block and multi-mesh grid generation technique is employed in a huge computational domain. The present computational results have not only confirmed the theoretical characteristics of a shock tube, but have also qualitatively presented the phenomena of reflected shock/boundary layer interaction and the starting process of nozzle flow. This numerical code is a useful tool to demonstrate the actual flow phenomena and to assist the design of experiments.