三維暫態直流電漿火炬模擬

Abstract

本研究使用有限體積法離散基於連續方程式、動量方程式、能量方程式、電磁場方程式及SST k-ω紊流模型的磁流體動力方程組，建立非傳輸型井式直流電漿火炬的三維暫態數學模型，並開發流場分析程式碼。本研究的火炬長690 mm，火炬半徑11 mm，模擬分析工作壓力為1大氣壓條件下，流量範圍為100 SLM至200 SLM間以及工作電流為100 A至200 A 間的空氣電漿火炬特性，並假定陰極弧根以1000 Hz頻率環繞火炬內壁移動。本研究利用迴歸分析計算結果顯示電弧長度正比於工作電流的-1.008次方以及入流流量的0.295次方；出口平均軸向速度正比於工作電流的-0.754次方以及入流流量的1.691次方；出口平均旋向速度正比於工作電流的-2.061次方以及入流流量的3.491次方；出口平均溫度正比於工作電流的-0.415次方以及入流流量的0.427次方。

This study develops a numerical framework where a finite volume method is used to discretize the MHD equations consisting of the continuity, momentum, energy, Maxwell's equations and the SST k-ω turbulence model. A three-dimensional unsteady model is established to simulate a non-transferred direct-current plasma torch equipped with well-type cathode. The investigated torch has a length of 690 mm and a radius of 11 mm. The plasma torch flow is calculated at an inlet flow rate ranging from 100 SLM to 200 SLM and a working current ranging from 100 A to 200 A. The working pressure is 1 atm where the cathode spot is assumed to have a circulation frequency of 1000 Hz. With the help of a regression analysis, the arc length is predicted to grow with I^(-1.008) and Q^0.295; the mean axial velocity at the outlet is predicted to grow with I^(-0.754) and Q^1.691; the mean tangential velocity at the outlet is predicted to grow with I^(-2.061) and Q^3.491; the mean temperature at the outlet is predicted to grow with I^(-0.415) and Q^0.427.