The vibration frequency of the last stage long turbine blade with self-locking shoulder is different due to the different contact states and contact stress of the working surface at different rotating speeds

which presents typical non-linear characteristics

and resulting in certain difficulties in numerical analysis for the turbine blade vibration characteristics. In this paper

the finite element contact method is used to analyze the contact area

contact stress and other contact states of a low-pressure last stage long blade at different rotating speeds

and then the vibration characteristics of the blade system at different pitch diameters and different orders are analyzed. Finally

the “3-coincide point” resonance frequency and resonance speed of the blade in the rotating speed range of 1 300～3 200 r/min are measured in the dynamic balance chamber by using the radio non-contact testing method

and the results are compared with the numerical results. The comparison shows that

the experimental results are consistent with the numerical calculation results

and the 880 mm blade-disk system does not have “3-coincide point”resonance near the working speed.