| Turbo pump is the core component of liquid rocket engine,which directly determines whether the rocket engine can run safely.The liquid seal is a key component for controlling the leakage of the turbo pump,which has important significance for the efficiency of the turbo pump and the vibration of the turbo pump rotor.Considering that the seal needs to be under severe working conditions of high pressure and low temperature,an annular clearance seal is o ften used as main sealing component for controlling leakage of the liquid oxygen fluid due to simple structure and less deformation.Therefore,the clearance seal at the shoulder of the centrifugal wheel in turbo pump is studied,and a new type of liquid seal with a texture added on its surface is proposed to study the leakage characteristics and dynamic characteristics of the textured clearance seal-rotor system.Firstly,the effects of different topography and distribution of the textured surface on the leakage are investigated by CFD simulation,and a better leakage profile scheme is obtained to get the proposed textured clearance seal calculation model.And the test method of seal leakage and dynamic characteristics proposed in this paper is applied to verify the accuracy of the CFD method.Secondly,for the study of seal leakage characteristics and dynamic characteristics,this paper presents a CFD-Bulk flow hybrid calculation method for textured clearance seal.Firstly,the flow equation in the seal cle arance is simplified to construct the Bulk flow model with variable clearance height.Then,leakage results obtained by steady-state simulation of CFD correct correlation coefficients of this model.Finally,using the finite element method to solve the flo w field.Compared with the simulation results of the seal dynamic characteristics by CFD dynamic grid technology,the accuracy of the proposed method is verified,which means the method has high computational efficiency and high reliability.Using this model,the variation of the leakage and dynamic characteristic coefficient of textured clearance seal under different sealing clearance,sealing length,pressure difference,rotation speed and eccentricity are obtained in this paper.And under the above-mentioned variable working conditions,compared with non-textured clearance seal,both the leakage and the stiffness coefficient are reduced,and the damping coefficient is increased.Finally,for the study of system dynamics characteristics,combined with the equations of rotor motion of the liquid-oxygen turbo-pump is established,and considering the equivalent material properties of some shaft segments,the simplified structure of the wheel and the support structure,the textured clearance seal-rotor system model is built by the finite element method.And the critical speed and mode shape is obtained.At the same time,an algorithm that considers the coupling the seal excitation force with the rotor vibration displacement is proposed.The vibration response of the shaft end nut,seal and pump end bearing under unbalanced excitation is obtained,and the reduction of the seal clearance and the increase of the seal length contribute to the reduction of the vibration level of the turbo pump rotor.The research shows that the textured clearance seal proposed in this paper has good effect on the leakage control and vibration reduction compared to the non-textured clearance seal.It provides technical support for the improvement of the performance of liquid rocket engine turbo pump. |
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