CAJ | 학술논문

采用数值模拟方法分析了35°倾斜角三分螺旋折流板换热器壳侧流体流动特性, 重点考察了壳侧通道的二次流分布.在子午切面上的结果表明: 壳侧通道内轴心区域的流体受螺旋流动离心力的作用存在向外扩张的趋势,而外围区域的流体在向心力的作用下存在向轴心流动的趋势;在壳侧通道的每个螺旋周期内,流线分成上下2股,并在左侧折流板附近形成迪恩涡,在右侧折流板附近开始向心流动并最终被吸进轴向主流中.一个螺旋周期内平行的2块折流板之间多个平行切片的结果进一步证实了二次流的存在,同时还显示了V形缺口处存在的倒流现象.二次流有利于螺旋通道内流体的掺混,有效促进主流流体与近壁流体的动量和质量交换,从而可强化此类换热器的传热.
채용수치모의방법분석료35°경사각삼분라선절류판환열기각측류체류동특성, 중점고찰료각측통도적이차류분포.재자오절면상적결과표명: 각측통도내축심구역적류체수라선류동리심력적작용존재향외확장적추세,이외위구역적류체재향심력적작용하존재향축심류동적추세;재각측통도적매개라선주기내,류선분성상하2고,병재좌측절류판부근형성적은와,재우측절류판부근개시향심류동병최종피흡진축향주류중.일개라선주기내평행적2괴절류판지간다개평행절편적결과진일보증실료이차류적존재,동시환현시료V형결구처존재적도류현상.이차류유리우라선통도내류체적참혼,유효촉진주류류체여근벽류체적동량화질량교환,종이가강화차류환열기적전열.
The flow characteristics of shell-side fluid in the tube-and-shell heat exchangers with trisection helical baffles with 35° inclined angles are numerically analyzed. The secondary flow distribution of the fluid in the shell-side channel is focused on. The results on meridian planes indicate that in the shell-side channel, the center part of fluid has an outward tendency because of the centrifugal force, and the peripheral region fluid has an inward tendency under the centripetal force. So in a spiral cycle, the fluid is divided into the upper and lower beams of streamlines, at the same time the Dean vortices are formed near the left baffle, and then the fluid turns to centripetal flow near the right baffle. Finally the two beams of streamlines merge in the main flow. The results of a number of parallel slices between two parallel baffles with the same sector in a swirl cycle also show the existence of the secondary flow and some backward flows at the V-gaps of the adjacent baffles. The secondary flows have a positive effect on mixing fluid by promoting the momentum and mass exchange between fluid particles near the tube wall and in the main stream, and thus they will enhance the heat transfer of the helix heat exchanger.