Calibration Accuracy for Constant Temperature Thermal Anemometer

Thermal anemometry is widely used to measure fluid velocity and boundary shear stress. Sensor calibration is required and results in a nonlinear equation with anemometer voltage as a function of fluid velocity or shear stress. Uncertainties in the parameters of the nonlinear equation are a source of uncertainty in measured values. A method for quantifying the calibration accuracy is presented using regression analysis with 95% confidence and prediction intervals. The proposed method is applied to shear stress measurements of a calibrated flush-mounted hot-film sensor. Shear stresses ranged from 0.6 to 6.8 Pa. Calibration accuracy was found to be within 15% of the absolute shear.