Numerical Simulation Of Bubbly Flow In Oscillation Heat Pipe Based On The Front Tracking Method

Compared to the traditional heat pipe, oscillating heat pipe which has a lower cost, higher heat transfer coefficient, and higher flexibility, is an excellent new type of heat exchange equipment, due to its potential for high heat transfer capacity, fast thermal response, simple and cheap construction. So oscillating heat pipe will certainly play an important role in cooling of electronic products. In order to study the flow pattern in oscillating heat pipe, this paper focuses on the capillary which is part of oscillating heat pipe. Since the bubble inside oscillation heat pipe is the foundation of flow pattern changes, so it has great significance in the study of bubble motion. In this paper, bubble motion in the capillary is numerically simulated by using Front Tracking Method(FTM).Rayleigh-Taylor instability( RT instability) is a classical problem of computational fluid dynamics, and the FTM algorithm replay this phenomenon quite well. The simulation result reveals that density, viscosity, surface tension can effectively influence the interface instability development. For bubble movement inside the capillary, paper studies the motion of the three bubbles, and bubbles are in a triangular distribution, such a distribution by taking into account both the positional relationship and the distance between bubbles. Firstly, the apex angle of the triangular that consists of the same size bubble is 30 °, 60 °, 90 °, respectively. The results show the distance between bubbles will affect whether the coalescing occurs. Secondly, analysis of the movement of two different bubble diameter ratios show size and relative position between bubbles affect movement of the bubble by wake and back flow(based on the apex angle of 60 °). Thirdly, analysis of the movement of different shapes bubbles show that when the top bubble is the ellipse, it will not change the structure of the flow field, but the bubble coalescence process is influenced; when the bottom of the bubble is the ellipse, it will change the structure of the flow field, and the bubble coalescence process is more complicated. Finally, analysis of the quantity of the bubbles show the number of bubbles are larger, the coalescence process is more complex, even the bubble breakup, the droplets coerce. In order to show the natural situation of movement within the pipe, a three-dimensional FTM program is taken into consideration. Preliminarily using three-dimensional program simulate the upward motion of single bubble of different diameters and jet penetration of the bubble. It was found that the diameter size of the bubbles have a greater influence on the process of deformation in the bubble motion, and the higher Weber number is, the higher jet intensity of bubble is, even penetration. With the increasing number of bubbles and a program from 2D to 3D, the complexity of the algorithm is rising sharply. Therefore,using CUDA to achieve parallel accelerated computing of FTM on GPU can enhance the efficiency of the program.