Impulse force-measurement system

Shock tunnels are important ground test facilities that can generate high-enthalpy flow. Flight velocity at a high Mach number can be simulated for aerodynamic testing of chemically reacting flows. However, the application of these tunnels is limited due to the only milliseconds-long test duration, especially for aerodynamic force measurement using traditional strain gauge balances. This study presents an impulse force-measurement system, which was used for a large-scale test model to measure its drag in a high-enthalpy shock tunnel with an approximately 3-7-ms test time. Force tests were conducted for a cone in the JF-10 high-enthalpy shock tunnel in the Institute of Mechanics, Chinese Academy of Sciences. An integrated design of the impulse force-measurement system was proposed for load measurement over a short duration, for which a recommended design criterion is that the measurement period be a minimum of twice the period corresponding to the lowest natural frequency of the measurement system. The current measurement technique breaks the limitations of the application of the conventional strain gauge balance. As an integrated measuring system, the impulse force-measurement system expands the structural design concept of strain gauge balances. The impulse force-measurement system performed well in the present tests. The test results show differences from the numerical simulations and some data obtained in a conventional wind tunnel. A preliminary analysis was performed on the real gas effects on the aerodynamic force.