Prediction of flow induced vibrations in vertical turbine pumps using one-way fluid-structure interaction

Abstract

Centrifugal pumps/vertical turbine pumps are important and critical equipment for operation in the power generation, water supply, process industries and petrochemical industries. All centrifugal and vertical turbine pumps have rotors and structures that can vibrate in response to excitation forces. Mechanical and hydraulic unbalance are the two major factors which can create dynamic effects in terms of pump vibrations. In many cases the resulting hydraulic forces due to hydraulic unbalance has much the same effect as the mechanical unbalance. The vibrations in the pumps must be within acceptable limits of applicable standards. If there is higher level of vibrations, it not only leads to operational inefficiencies but also causes pump failures. Hence, it is very important for designers to understand the dominating fact of unbalance force and its origin. The prediction of vibrations in a vertical turbine pump due to the hydro dynamic forces, using numerical methods can help a designer to accomplish a successful design. The interaction between solid and fluid in present case can be completed by one-way coupling method. The one-way fluid-structure interaction approach is presented in present paper to predict the vibrations at specific operating condition which has good correlation with the test data. The advantage of reduced computational effort in this approach can be utilized during initial design stage. In this paper, a case study of one-way FSI approach of a vertical turbine pump is discussed. After detailed explanation about the CFD results, one-way coupling approach is explained with comparison of vibration displacements in both numerical and test data.