Experimental Study of the Effects of Metal Particles on the Flow and Mixing Characteristics of Gas-Liquid Two-Phase Under Oscillation Conditions
To further improve the heat transfer performance of the cooling gallery of diesel engine pistons,metal particles introduced to enhance the degree of two-phase mixing under oscillation conditions.By using the oscillating flow experimental method and combining it with digital image processing techniques,the kinematic characteristics of metal particles under oscillation conditions and the characteristics of two-phase oscillating flow were studied.The effects of rotational speeds and filling ratios on the motion of metal particles,as well as the maximum bubble diameters and mixing rates,were further discussed.The results show that rotational speed is the main factor affecting the oscillating flow effects of gas-liquid two-phase flow.With the increase of rotational speeds,the time for metal particles to reach the top wall of the cooling gallery is shortened,resulting in an increase in instantaneous velocities.Compared to 270 r/min,the average velocity change rate of metal particles impacting the top wall increases by 133%at 330 r/min,indicating an increase in the intensity of wall impact.Compared to the filling ratio of 25%,the maximum instantaneous velocity of metal particles impacting the top wall is reduced by 68%at the filling ratio of 75%,indicating a decrease in the intensity of wall impact at high filling ratios.At filling ratios around 50%and under high rotational speed conditions,the intensity of particle impact on the wall is reduced,but the degree of gas-liquid two-phase mixing is the best.
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