A new method for improving the measurement sensitivity of wind tunnel balance

The sensitivity of traditional measurement of small scope aerodynamic force is not very high.Aiming at this problem,this paper introduces a new measurement method:Displace-ment measurement method.It means setting two grooves at the same place as where the tradi-tional gauges are pasted,then measuring the displacement of the grooves as it changs when the grooves are loaded to get the balance formula.Here take three kinds of single component bal-ances as an example:One traditional strain balance and two kinds of the displacement balances with different grooves.The traditional balance and the displacement balance with 2mm grooves are pasted with two kinds of strain gauges,which are the optical fiber strain gauge and the strain gauge respectively,to compare the performance of both the gauges and the measurement meth-ods.And an optical fiber strain gauge is used in the displacement balance with 1mm grooves to compare the different sensitivity caused by different depths of the grooves.The static calibration test and the finite element simulation are carried out,and we can draw conclusions as follows:The new measurement method can improve the sensitivity compared to the traditional methods, and the deeper the groove is,the higher the sensitivity becomes.For example,the sensitivity of the new balance with 2mm deep grooves is improved by 3 times compared to the traditional strain balance,1.57 times compared to the 1mm deep grooves.The accuracy of the new balance with 1mm deep grooves is 0.02%,meeting the accuracy requirements.The accuracy of the balance with 2mm deep grooves is 0.09%.It thus shows that increasing the depth of the grooves would lower the accuracy,which may be caused by the decrease of the rigidity of the balance.Therefore the size of the grooves should be chosen carefully.This paper provides a new idea for small scope aerodynamic force measurement.