Effect of working fluid, acceleration and heater power on temperature profile inside a thermal convective accelerometer

Convective accelerometer does not contain seismic mass and work based on free convection heat transfer of electrical heater inside a hermetic chamber. Its sensitivity is dependent to the temperature distribution of working fluid inside the hermetic chamber. In this paper, the effect of working fluid properties, acceleration and heater power on temperature profile inside the convective accelerometer hermetic chamber is presented. Convective accelerometers with various working fluids (air, carbon dioxide, water, nitrogen, argon, helium, and ethylene glycol), heater powers (0.1 to 1.0 watts), and accelerations (1 to 5 g) were simulated by using ConventorWare 2010 software. Result shows, without acceleration the temperature profile of working fluid is symmetry around the vertical axis in relation to the heat source while with acceleration, the temperature profile is slightly skewed towards the acceleration direction. Argon is the best candidate for working fluid because it produces the largest temperature difference between the left and the right sides of the heater which would result in high sensitivity accelerometer. Convective accelerometer sensitivity also can be enhanced by increasing heater power, using gas-phase working fluids and locating the temperature sensors in the range between 100 to 300 μm away from the heater.