Abstract: A wind tunnel fluctuating pressure test technology using aeroelastic scaled model of launch vehicle is established. The aeroelastic scaled model is similar to the launch vehicle in geometry and reduced frequency. A Wind tunnel test using both rigid scaled model and aeroelastic scaled model of a hammerhead launch vehicle is conducted to measure fluctuating pressure on model surface and to evaluate influence of vibration on unsteady pressure. Mach number of the test is 2.5. Test results suggest that flow field of rigid model has no characteristic frequency while flow field of elastic model at small angle of attack encounters dominant frequencies which are exactly the first order model structural frequency and its multiplication. Also，the RMS values of fluctuating pressure increase tremendously when fluid structure interaction occurs. At high angle of attack the RMS values of fluctuating pressure on elastic model decrease to the level near rigid model results as fluid structure interaction weakens. The strain at the base of elastic beam is measured and result shows there is half cycle phase difference between vibration and pressure signal of 1st order characteristic frequency at divergent stage. Finally the interaction between pressure and structure reaches limit cycle oscillation stage and phase difference decreases to nearly zero. These phase differences have an impact on the capacity of doing work on structure by flow.

Key words: aeroelastic scaled model, reduced frequency, fluctuating pressure, wind tunnel test, fluid-structure interaction, phase difference