3-D numerical and experimental analysis of a built-in motorized high-speed spindle with helical water cooling channel

The purpose of this paper is to numerically and experimentally analyze the three-dimensional fluid motion and temperature distributions in a built-in motorized high-speed spindle with a helical water cooling channel. The effects of different heat sources (q = 60 W, 120 W and 240 W, which correspond to heat flux q″ of 1.43 W/cm2, 2.8652 W/cm2 and 5.7304 W/cm2, respectively), cooling water flow rate (0.4 L/min, 0.8 L/min and 1.2 L/min, which correspond to cooling water velocity 0.24 m/s, 0.48 m/s and 0.72 m/s, respectively) are examined in detail. The model is based upon a custom-built high performance spindle, which is used in the printed-circuit board (PCB) industry, of 1.5 kW and a maximum speed of 160,000 rpm. The results indicated that almost all the hot spots are concentrated near the center of the spindle axis, and temperature increase can be significantly reduced with helical water-cooling. The predicted temperature distribution of the spindle housing is in good agreement with the result obtained from experiments. It is also shown that the heat transfer coefficient h varies with V0.184. Regression analysis was conducted to obtain Nu = 4.63Re0.184, which can be applied for 5 × 104 < Re < 1.5 × 105.