背压扰动平衡盘对涡旋压缩机黏性内流压力影响研究

Influence of back pressure disturbance balance disc on viscous internal flow of scroll compressor

在变转速工况下,电动涡旋压缩机背压腔中润滑油产生的背压力无法准确平衡轴向气体力。针对这一问题,提出了一种带有扰动片的背压扰动平衡盘,研究了背压扰动平衡盘对涡旋压缩机黏性内流压力的影响。首先,对背压扰动平衡盘作用原理进行了分析,使用贝塞尔曲线构建了扰动片型线,对润滑油被扰动后的静压增量进行了公式推导,计算了扰动片出口安装角和扰动片数对润滑油静压的影响;然后,建立了含背压扰动平衡盘的背压腔模型,将流体域分为旋转域和静止域,采用旋转坐标系的方法进行了数值模拟,研究了背压腔内润滑油的压力场;最后,根据理论计算,模拟了润滑油在不同出口安装角和扰动片数下的润滑油静压,对润滑油静压与压缩机所需最佳背压进行了对比分析。研究结果表明:采用背压扰动平衡盘可以使润滑油静压增加21%,且静压增量随主轴转速的增加而增大,适当增大扰动片出口安装角可使润滑油静压增加0.032 MPa;对比最佳背压可知,扰动前润滑油静压与最佳背压相差26%,而合理设计扰动片后的润滑油静压与最佳背压相差仅为9%,极大改善了电动涡旋压缩机在变转速下的轴向平衡。

Aiming at the problem that the back pressure generated by the lubricant in the back pressure chamber of the electric scroll compressor can not balance the axial gas force accurately under the working condition of variable rotational speed,a back pressure disturbance balancing disk with a disturbance piece was proposed.Firstly,the principle of the back pressure disturbance balance disk was analyzed,the Bezier curve was used to construct the disturbance piece profile,the static pressure increment of the disturbed lubricant was derived and the influence on the outlet installation angle and the number of the disturbance piece on the static pressure of the lubricant were calculated theoretically.Then,the model of the back pressure cavity containing the back pressure disturbance balance disk was established,the fluid domain was divided into the rotating domain and the fixed domain,the numerical simulation was carried out with a rotating coordinate system and the pressure field of the lubricant in the back pressure chamber was studied.Finally,the static pressure of the lubricant at different outlet installation angles and different number of disturbance pieces was simulated according to theoretical calculations and analyzed in comparison with the optimal back pressure of the compressor.The research results show that the back pressure disturbance balancing disk can make the lubricant static pressure increase by 21%and the static pressure increment increase with the increase of spindle speed.The appropriately increased disturbance piece outlet installation angle can make the lubricant static pressure increase 0.032 MPa.After comparing with the optimal back pressure,the difference between lubricant static pressure and the optimal back pressure before disturbance is 26%,while the difference between the lubricant static pressure and the optimal back pressure after the reasonable design of the disturbing piece is only 9%,which greatly improves the axial balance of the electric scroll compressor at variable speed.