Dynamic characteristics of piston ring end-sealed squeeze film damper considering bubble dynamics: part 1—modeling and numerical simulation
摘要
Bubble/oil mixture are prevalent in end-sealed squeeze film dampers (SFDs). Based on a homogeneous mixture model, this paper develops a comprehensive numerical method for analyzing cavitation and dynamic characteristics in end-sealed SFDs by coupling the Reynolds (RE) and complete Rayleigh-Plesset (RPE) equations, both incorporating temporal and advection inertia effects. To enhance numerical stability, the RPE is solved using Numerical Differentiation Formulas (NDFs) rather than the explicit Euler method. Compared with experimental and numerical film pressure results, the proposed method more accurately predicts pressure in cavitation regions due to the inclusion of bubble dynamics. Numerical simulations investigate how inertial effects, surface dilatational viscosity, oil supply pressure, orifice loss coefficient affect hydrodynamic pressure, void fraction, inertia, and damping coefficients in end-sealed SFDs varying whirl frequencies and amplitudes. Accounting for bubble dynamics, the fluid withstands tensile stress that, along with valley pressure, decreases with lower surface dilatational viscosity; using 7.85 × 10−4 N s/m is adequate since reasonable variations negligibly impact inertia and damping. Introducing inertia raises peak pressures by over 15% near the feed-port at high whirl frequencies. Feed-ports enhance film inertia, distort the pressure field, and reduce local cavitation by more than 50%. Higher supply pressure also suppresses cavitation and increases inertia and damping, depending on frequency and bubble dynamics. Conversely, larger orifice loss coefficients, relating to the structural parameters and inlet flow velocity, increase the backflow rate and reduce inertia and damping. These results highlight the need to tailor optimal oil supply and orifice design to specific operating conditions.