Impact of cavity shape on thermal accelerometer parameters

International audience ; Many kinds of accelerometers have been developed for measuring vibration and shock in different application. Thermal accelerometer, developed for the last fifteen years, present good advantages since it works on thermal convection with no moving parts and could survive very high levels of shock up to tens to thousands of g. The sensor principle is based on free convection in a cavity containing a gas. It is composed of a heating resistor placed in the middle of the chamber between two temperature detectors. Under the influence of an acceleration Γ, the temperature profile shifts and the balance is modified creating a temperature difference on the detectors equal to δT, proportional to the applied acceleration, giving an equivalent sensitivity S = δT/Γ (°C/g). The present abstract show the evolution of sensibility as a function of acceleration for five geometries. These results have been carried out by CFD simulation with Fluent® software. We have also reported the sensitivity issued from the simulation experiment as a function of cavity diameter. We can conclude that in steady state, the shape of the sensors has little or no influence on the sensor response.