Design and experiment of the centrifugal pump impellers with twisted inlet vice blades

In order to introduce gap drainage technology into practice, the design concept and expression format of spatial geometry are proposed for gap drainage impeller with twisted vice blades. First, the profile of vice blade at leading edge and relative position of main blade need to be parameterized. In addition, the influence of these parameters on the performance of a centrifugal pump should be studied. After the above-mentioned work is done, a centrifugal pump with good performance can be designed. On the basis of previous research results, the geometric parameters of twisted blades are determined and the centrifugal pump impellers are designed and manufactured. Through performance tests and cavitation tests, it is verified that the twisted vice blades on centrifugal pumps are effective and practical.

Nonlinear transient responses of rotating twisted FGM cylindrical panels

This paper develops a new structure dynamic model to investigate nonlinear transient responses of the rotating blade made of functionally graded material(FGM). The rotating blade is simplified as a rotating FGM cylindrical panel with a presetting angle and a twist angle. The geometric nonlinearity effects are taken into account in the strain-displacement relationships, which are derived by Green strain tensor. Based on the first-order piston theory and the first-order shear deformation theory, the equations of motion for the rotating twisted FGM cylindrical panel are acquired by means of Hamilton principle and Galerkin method.Backward Differentiation Formula(BDF) and Runge-Kutta Algorithm are used to solve the nonlinear equations of motion for the system. The effects of four pulse load conditions on the system subjected to the internal pulse load or the external pulse load are fully discussed. A detailed parametric analysis is performed by considering the effects of the rotating speed, volume fraction index and temperature.

Dynamic characteristics of a shrouded blade with impact and friction

A simplified computational model of a twisted shrouded blade with impact and friction is established.In this model,the shrouded blade is simulated by a flexible Timoshenko beam with a tip-mass,and the effects of centrifugal stiffening,spin softening,and Coriolis force are considered.Impact force is simulated using a linear spring model,and friction force is generated by a tangential spring model under sticking state and a Coulomb friction model under sliding state.The proposed model is validated by a finite element model.Then,the effects of initial gap and normal preload,coefficient of friction,and contact stiffness ratio(the ratio of tangential contact stiffness to normal contact stiffness)on system vibration responses are analyzed.Results show that resonant peaks become inconspicuous and impact plays a dominant role when initial gaps are large between adjacent shrouds.By contrast,in small initial gaps or initial normal preloads condition,resonant speed increases sharply,and the optimal initial normal preloads that can minimize resonant amplitude becomes apparent.Coefficient of friction affects the optimal initial normal preload,but it does not affect vibration responses when the contact between shrouds is under full stick.System resonant amplitude decreases with the increase of contact stiffness ratio,but the optimal initial normal preload is unaffected.