Influence of structure parameters on aeroelastic stability for labyrinth seal based on energy method

Numerical analysis of turbomachinery based on energy method is used to predict the aeroelastic stability of the straight-through labyrinth seal by solving aerodynamic work and vibration modes has been compared.It's found that the increase of pressure ratio leads to the in the circumferential direction of the labyrinth seal corresponds to the number of vibrating nodal diameters.In order to investigate the influence of structure parameters,the effect of relative thickness of the tooth tip,the width of the seal cavity and the eccentricity of the rotor on the aeroelastic stability of the labyrinth seal has been studied.The result of numerical calculation shows that the change of the structural parameters can affect the aeroelastic stability of the labyrinth seal to a certain extent,and can be applied in the structural optimization.

Aeroelastic stability of full-span tiltrotor aircraft model in forward flight

The existing full-span models of the tiltrotor aircraft adopted the rigid blade model without considering the coupling relationship among the elastic blade, wing and fuselage. To overcome the limitations of the existing full-span models and improve the precision of aeroelastic analysis of tiltrotor aircraft in forward flight, the aeroelastic stability analysis model of full-span tiltrotor aircraft in forward flight has been presented in this paper by considering the coupling among elastic blade, wing, fuselage and various components. The analytical model is validated by comparing with the calculation results and experimental data in the existing references. The influence of some structural parameters, such as the fuselage degrees of freedom, relative displacement between the hub center and the gravity center, and nacelle length, on the system stability is also investigated. The results show that the fuselage degrees of freedom decrease the critical stability velocity of tiltrotor aircraft, and the variation of the structural parameters has great influence on the system stability,and the instability form of system can change between the anti-symmetric and symmetric wing motions of vertical and chordwise bending.

Aeroelastic analysis and structural parametric design of composite rotor blade

Based on FEM theory,a method of dynamic analysis for hingeless rotors considering anisotropic composite materials is established.A parametric modeling method of composite blade with typical profile and high simulation degree for design is proposed.Through the finite element method,the profile characteristics of rotor blade can be obtained efficiently and accurately,and the synchronization of parametric design and finite element analysis of structural characteristics can be realized.Then a 23-degrees of freedom non-linear beam element is used to simulate the extended one-dimensional beam,thereby a nonlinear differential equation describing the elastic motion of the rotor is established.To obtain the crosssectional target characteristics of the blades,an inverse design method is proposed for cross-section components based on combinatorial optimization algorithm.The calculation and validation work show that the proposed model can effectively analyze the aeroelastic characteristics of general composite rotors.Further,the influence of cross-sectional parameters on the aeroelastic stability and hub loads of hingeless rotor is analyzed and some remarkable conclusions are obtained.

Aeroelastic vibration analysis of a 1.5 stage compressor

Aeroelastic vibration problems are commonly found in modern compressors operating in off-design conditions.Large amplitude vibration could lead to high cycle fatigue(HCF)of blade and usually occurs in front stages of axial compressors.In this study,the influence of tip gap size on aeroelastic stability is analyzed in a 1.5 stage compressor with an in-house fluid-structure interaction code.A three-dimensional unstructured finite-volume compressible flow solver is applied in the fluid domain and a structure dynamic solver with the modal superimposition method for blade motion is used in the structure domain.Rotor tip clearances of 1%,2%and 3%of tip axial chord at maximum rotor loading conditions at off-design speeds are analyzed for aeroelastic stability.The tip leakage flow and vortex structure can be seen near the blade tip region at a larger tip gap size.The aeroelastic stability of rotor blade at different tip gap sizes is mainly influenced by the 1st torsion mode,and the variation of aerodynamic damping is not monotonous.The intensity of the tip vortex and shock wave are the key factors affecting the aeroelastic stability of rotor when tip gap size increases.