A 25kW Shield Sump Dynamic Performance Check And Analysis

In this thesis the structure dynamic characteristic of a 25kW Ex pump is studied. Firstly,the vibration modes and transmission paths of main parts of the pump and the whole pump unit are analyzed, and the isolation characteristic is numerically calculated. Then the pulsating pressure is numerically simulated. Finally the natural characteristics and the unbalance response of the rotor are numerically analyzed. The results show that:1) The vibration modes of the whole pump unit retain all of the stator modal shapes, but the frequency offset exists: This is caused by the weight increase added on the stator by the rotor,coupling relationship exists between the rotor and stator; rotor modal partially changes because of the boundary conditions changed from free boundary condition to bearings constraints; explosion-proof pump machine natural frequency and the frequency axis do not coincide with the natural frequency of the rotor shaft frequency band and leaves are far away,so the pump and the shaft does not resonate; isolator BE400 selected in the isolation design is appropriate.2) Frequency of the main shaft mains the fluid excitation, leaf-frequency amplitude is small; fluid incentives increased rapidly in the impeller and the impeller outlet fluid excitation amplitude maximum frequency component, fluid incentives in the diversion channel is most complex, but amplitude is below the impeller exports, but in the same order of magnitude,volute fluid excitation frequency composition is stable; pressure pulsations caused by interference effects upward to the impeller, downward to volute internal , diversion channel and pump outlet.3) By the explosion of critical speed of the pump rotor and the rotor unbalance response for a given amount of unbalance, result shows that: the rotor shaft first critical speed is 4461r/min,explosion-proof rigid rotor pump rotor is vertical, not through the first order critical speed; By a conservative calculation of rotor unbalance response, response obtained at the maximum displacement is less than the bearing clearance, which illustrates the bearing parameter linearized rationality; the displacement response on the bearing near the main impeller is a extremum at about 75Hz, rotor is operating near first critical speed, and which on the bearing near auxiliary impeller occurs an enormous response which is the first extremum in 86Hz or so, in line with the results of analysis of the inherent characteristics of the rotor.This paper argues that it can be further optimized impeller from the following: impeller continuity to some extent affects the characteristics of the fluid excitation, impeller satisfy the continuity that is at rated conditions, in the infinitely leaves condition, according to all the theoretical flow lines, all surface area whose surface keeping vertical with the flow lines is equal. The object of this paper, in accordance with the above principles to optimize impeller,reducing the vortex by Eliminating flow channel discontinuity, thereby reduce fluid incentives.after optimization of the impeller, the secondary flow effects may be still causing large swirl,the vortex region can be separated simply by adding the short blade, the bias angle may be designed in accordance with the existing data, or can be given from the experimental .Since the jet-wake phenomenon, the circumferential direction of the impeller exit fluid energy causes a large uneven distribution which causing the fluid pressure pulsation. It can be solved by optimizing the flow channel to uniform the impeller outlet fluid energy distribution in the circumferential direction.