面向电主轴定子冷却的热管流动与传热数值模拟

Numerical Simulation of Flow and Heat Transfer of Heat Pipe Used for Stator Cooling of Motorized Spindle

针对高速电主轴运转时产生大量热量、严重影响加工精度的问题,提出了一种面向高速电主轴定子冷却的环路热虹吸管,将其应用于电主轴定子散热,相对于传统定子水套,具有更高效和不消耗泵功等优点。建立了热管管内气液两相流动及相变传热数值计算方法,并用实验数据对该方法进行了验证,然后模拟研究了不同工质(正戊烷、乙醇、水)和不同加热功率对热管流动与传热性能的影响。结果表明,数值模拟方法能准确捕捉到管内气液两相的流型和相变换热过程,与实验数据吻合较好;工质为正戊烷和乙醇时,冷凝段形成冷凝液膜,在相同工况下,乙醇的液膜厚度比正戊烷小20μm左右;而工质为水时,冷凝段形成液滴,具有较高的传热系数;在相同条件下,以水为工质时,单环路热虹吸管热阻最小,在90 W加热功率时,热阻为0.085 K·W^(-1),分别比以正戊烷和乙醇为工质时小35.2%和11%左右。

High-speed motorized spindle is the main heat source of CNC machine tools,which seriously affects machining accuracy.Compared with the traditional stator water jacket,applying the heat pipe to the stator of the electric spindle to dissipate heat has the advantages of higher efficiency and no pump power consumption.The loop thermosyphon with special structure is proposed for high-speed motorized spindle stator cooling in this paper.A numerical calculation method for the vapor-liquid two-phase flow and phase change heat transfer in the heat pipe tube is established,the proposed method is verified through experimental results,and this method is used to study the influence of different working fluids(n-pentane,ethanol,water)and heating power on flow and heat transfer performance of heat pipe.The results show that the numerical simulation method can accurately capture the gas-liquid two-phase flow pattern and phase change thermal process in the tube,which is in good agreement with the experimental data.A condensate film is formed in the condensation section when the working fluid is n-pentane and ethanol,and the liquid film thickness of ethanol is about 20μm smaller than that of n-pentane under the same working conditions.Droplets are formed in the condensation section when the working fluid is water,which leads to higher heat transfer coefficient.The thermal resistance of the heat pipe with water as the working fluid under the heating power of 90 W is about 35.2%and 11%lower than that of n-pentane and ethanol,respectively.