Experimental Study on the Static Stability of Scallop Damper Seals

An experimental method for identifying the aerodynamic force and static stiffness of the scallop damper seals was proposed, and the variation characteristics of the static aerodynamic force and static stiffness under different inlet pressures and eccentricities were investigated. Results show that the numerical simulations of the aerodynamic force and static stiffness agree well with the experimental results. At the same inlet pressure, as the eccentricity increases, the aerodynamic force of the seal gradually increases, while the static stiffness coefficient gradually decreases, yielding a static stiffness coefficient ranging approximately from -6 to 40 kN/m. As the inlet pressure increases, both the aerodynamic force and stiffness exhibit a trend of initially increasing and subsequently decreasing. Along the axial direction of the seal, there exists a pressure crossover point between the maximum and minimum clearances, where the pressure difference transitions from negative to positive. In the outlet section of the seal, the Mach number at the minimum clearance increases rapidly, converting pressure energy into mass inertial force. This causes the pressure at the minimum clearance to drop below that at the maximum clearance, thereby weakening the static stability of the scallop damper seal. Under non-choked flow conditions, the change in Mach number is relatively small, leading to better static stability.