Browsing by Author "Lai, Wei-Chia"

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Flow field investigation in a rotating disk chemical vapor deposition chamber with a perforated showerhead
(2017-11-01)
Liu, Yao-Hsien
;
Peng, Guan-Jhong
;
Lai, Wei-Chia
;
Huang, Chih-Yung
;
Liang, Jin-Hsing
A flow field in a simulated rotating disk chemical vapor deposition chamber in which the inflow gases entered through a showerhead inlet was experimentally investigated using particle image velocimetry. The deposition uniformity was highly related to the flow pattern, which was influenced by the buoyancy, centrifugal, and flow inertia forces. This study investigated flow patterns for different processing parameters, namely chamber heights (20 and 40 mm), jet-to-disk temperature differences (0-500 degrees C), and disk rotational speeds (0-500 rpm). The time-averaged axial and radial velocity profiles were determined for examining the effects of rotation and heating on flow uniformity above the rotating disk. The Reynolds stress and turbulence intensity was found to be influenced by the buoyancy and rotation induced flow. At a high jet-to-disk temperature difference, the upward buoyancy force lifted the flow and prevented the inlet flow from reaching the disk surface. The buoyancy-induced flow can be suppressed through disk rotation or chamber height reduction. Moreover, the nondimensional parameters (Grashof number and rotational Reynolds number) can be used to construct flow regime maps and quantify the effects of rotation and heating even with the contribution from different chamber heights, disk temperatures, and rotational speeds. (C) 2017 Elsevier Inc. All rights reserved.
Investigation of flow characteristics from an inclined jet on a heated rotating disk
(2018-12-01)
Lai, Wei-Chia
;
Yin, Peng
;
Liu, Yao-Hsien
;
機械工程學系
;
Department of Mechanical Engineering
Impinging jet directly hits the object surface to achieve drying, heating or cooling purpose. Jet flow and rotation parameters will affect the flow field. In this paper, the flow pattern and velocity distribution of the inclined jet on a rotating disk under different experimental conditions were investigated using particle image velocimetry (PIV). The investigated parameters included: jet Reynolds number (173-979), jet angle (45 degrees, 60 degrees, and 90 degrees), rotational Reynolds number (0-21,000), and Grashof number (0-300,000). The result showed that inclination angle could cause unsymmetrical flow velocities in the radial direction of the stationary disk. Also, the flow above the heated stationary disk was influenced by the vortex flow generated by the buoyancy force at lower inlet flow rate. However, the flow pattern was not affected by the jet angle at lower jet flow rate on the high-speed rotating disk. The flow pattern can be characterized by using a series of dimensionless parameters, including rotational Reynolds number, jet Reynolds number, and Grashof number. (C) 2018 Elsevier Ltd. All rights reserved.