Study on temperature characteristics and correction of strain gauge balance in actual airflow environment

Abstract

Strain gauge balances are main force measuring instruments used in high speed wind tunnels. As one of main performance of the strain gauge balance, accuracy plays a vital role in wind-tunnel test technologies. However, spatial temperature gradients across the strain gauge balance caused by the inner deformation of the balance due to temperature changes of the actual airflow environment, has some adverse influence upon the measurement accuracy of the strain gauge balance, especially for the long-duration testing in continuous wind tunnels. In order to better understand the temperature characteristics of strain gauge balances and improve their measurement accuracy, a study has been performed with the balance 30G and calibration model GBM-04A in the 0.6 m×0.6 m continuous transonic wind tunnel at China Aerodynamics Research & Development Center (CARDC), and a correction method for the bridge zero drifts of the strain gauge balance due to temperature gradients across the strain gauge balance for long-duration testing was developed. The study case shows that the deviation of measurement accuracy due to the non-uniform temperature gradient across the strain gauge balance body is about 0.0003 for the drag coefficient at M=0.6 on the calibration model GBM-04A, which can be corrected in a large extent with the method in this paper. In some extent, the correction method can be of great benefit to those long-duration tests in the continuous wind tunnel for its simple operation and high universality.