Chaotic vibration reduction of vertically suspended centrifugal pumps by the effect of the mechanical design parameter on hydraulic forces

Abstract

The chaotic vibration generated by slender rotor–stator contact in vertically suspended centrifugal pumps shows itself in wear and fatigue failure of shafts, bearings, wear rings, seals and impellers. In common design methods of rotary equipment, for validating designed products, virtual representations in Computer Aided Design tools are imported to simulation tools (e.g. ANSYS software) on the last step of the design process. In this research, the ability of a non-linear finite element model is examined to support decision-making, synthesis and interaction of design choices during earlier stages of design process. So, the back wear ring diameter as the adjustable mechanical design parameter is used to reduce chaotic behavior of the pump rotor without any difficulty in manufacturing or problematic effect on the major hydraulic properties. The non-linear finite element model of the rotor is discretized into an appropriate number of Timoshenko beam elements. The major non-linear terms, the geometric stiffening effect, and the gyroscopic effect are considered. Rotor–stator contact, considering the rotor–stator clearance and the rotor–stator friction coefficient are taken into account. The full-order equations of motion are obtained using Lagrangian approach and the finite element method, and then are integrated into a computational plan. This study presents an allowable domain of the mechanical design parameter in which chaotic vibrations of the slender rotor can be reduced effectively. Furthermore, this research shows a basic method in which some design stages can be run in parallel rather than in series can be used to reduce redesigning and optimization times.