Research on Pendulum Characteristic of Natural Convection Gas within Three-dimensional Spherical Closed Cavity

The pendulum characteristic of natural convection gas within three-dimensional spherical closed cavity is discussed. By using the Finite Element Method, the flow field and temperature field caused by the heat source, when the three-dimensional enclosure is inclined, has been calculated. The results are as follow: (1)Because of the buoyancy, the direction of natural convection gas is always vertical upward in dimensional enclosure, with the pendulum characteristic. (2) Compared to the level state, when the closed spherical cavity is inclined, temperature gradient near the heat source 0 and parallel to the reference line on both sides are unequal. Furthermore, the difference between temperature gradients on both sides increase with the increasing inclination angle, otherwise reduce. Temperature gradient difference AS and inclination angle 0 is in linear relationship. Using the characteristic, it can be used for sensitive inclination angle in sensor.