Structural design and stress analysis of a high-speed turbogenerator assembly supported by hydrodynamic bearings

Abstract

Turbine and bushing bearing are the most critical components of high-speed machines. This paper describes the design of a high-speed turbine supported by hydrodynamic bearings. The mathematical dimensioning and the FEM analysis are presented to validate the mechanical strength of the turbine and the bushing bearing models. Fatigue life and factor of safety are also determined. The simulations show that the maximum von Mises stress values obtained are associated with the centrifugal force generated by the system rotational movement. The results variation is mainly due to the properties of the materials proposed. For the turbine, 7075-T6 aluminum alloy and SAE 4340 steel obtained satisfactory behavior under a constant operating speed of 30,000 RPM. For the hydrodynamic bearing, the TM23 bronze alloy exhibited excellent results, without fracture, and low mechanical deformation. The models exhibited a great potential employment in several applications, such as biogas systems to generate electrical energy, and educational test bench for thermodynamic and tribological simulations. Keywords High-speed machines • Structural design • Steam turbine • Hydrodynamic bearings • FEM analysis List of symbols µ d Coefficient of dynamic friction Aα Turbine full-arc C y Blades theoretical velocity D m Mean blade diameter F f Dynamic friction force F N Normal force h e Input enthalpy h s Output enthalpy ṁ Mass flow ƞ i Internal efficiency ƞ m Mechanical efficiency R Mean radius of blades length u Tangential velocity v m Mean velocity coefficient Ẇ Power Z Number of blades Z min Minimum number of blades γ Specific internal work ε Coefficient of laminar steam flow ω Angular velocity

Designing and qualitative structural analysis of a warren truss bridge

“…Factor of safety (FOS) is the capacity of a structure beyond the applied loads (Bento et al, 2019). A calculated ratio of structural capacity to actual applied load (Eq.…”

“…Von Mises method was used in the stress and strain analysis of the proposed Warren type bridges due to the most reliable results, since the respective strength criterion considers intermediate stresses as reference (Li et al, 2018;Bento et al, 2019). Fig.…”