(1) Model change algorithm. This method is simple and reliable. The specific method is to first enlarge or reduce all geometrical dimensions of the overcurrent portion of a multistage centrifugal pump similar to the designed multistage centrifugal pump.
(2) Speed coefficient method. The velocity coefficient method is essentially a similar design method. Compared with the model-changing algorithm, the difference is that it is based on a series of similar multi-stage centrifugal pumps, rather than establishing a similar multi-stage centrifugal pump. basically. That is to say, the speed coefficient method is based on the similar principle, using the statistical coefficients of a series of excellent multi-stage centrifugal pumps to calculate the main dimensions of the impeller.
(3) Theoretical calculation method. Based on the basic equation of the vane pump, the method performs relatively accurate calculations on the outer diameter of the impeller and the exit angle of the vane, which usually requires iterative calculation.
Determination of basic parameters of multistage centrifugal pump impeller
In multi-stage centrifugal pump design, the given design parameters are generally required: flow Q, head H, speed N, NPSH NPSHr and efficiency. According to the above parameters, the structural formula of the centrifugal tip can be preliminarily determined and the specific rotation number Ns of the impeller can be calculated, and then some empirical data (formula) is used to determine the main geometrical dimensions of the impeller. In the hydraulic design of a multistage centrifugal pump impeller, it is assumed that the flow inside the impeller is an axisymmetric flow, and the velocity at any point in the flow field can be decomposed into the axial velocity component and the peripheral velocity in the axial plane (the plane containing the impeller axis). Component. The distribution of the axial velocity component is determined by the axial projection of the impeller runner and the boundary conditions at the impeller inlet, while the circumferential velocity distribution is determined by the distribution of the axial velocity component and the blade placement angle. Therefore, the first step in the design of the impeller is to determine the axial speed and circumferential speed.
