Analysis of rotor dynamic characteristics in turbine-type energy recovery devices for seawater desalination

As a critical energy-saving component in reverse osmosis desalination systems, turbine-type energy recovery devices require rigorous dynamic stability evaluation. To guarantee the safety and stability of these devices, this study employs free and constrained modal analyses of its rotor components using Ansys Workbench. The critical speeds, natural frequencies, and other pertinent parameters of the rotor under various rotational speeds and material properties are calculated. Additionally, the dynamic characteristics of rotors crafted from polyethylene, gray cast iron, stainless steel, structural steel, and 40Cr are examined. The findings reveal that the first six natural frequencies of the rotor in free mode are nearly zero, with the natural frequencies progressively increasing from the 7th to 12th modes, accompanied by varying degrees of deformation. Under constrained conditions, the modes of a turbine-type energy recovery device exhibit stability and are less susceptible to resonance. As the rotational speed varies, the natural frequencies of the modes gradually increase, with critical speeds emerging solely in the first three modes, specifically 93 336, 1.1786 × 105, and 1.3139 × 105 rpm, respectively. Furthermore, as the density and Young’s modulus of the rotor material increase, the first three critical speeds also exhibit a continuous upward trend. This research provides a foundational design basis for the structural stability of turbine-type energy recovery integrated machines.