Abstract
This paper aims to investigate the utilization of octet truss lattice structures in gas turbine blades to achieve weight reduction and improvement in vibration characteristics, which are desired for turbine blades to improve the efficiency and load capacity of turbines. A solid blade model using NACA 23012 airfoil was designed as reference. Three lattice-based blades were designed and manufactured via additive manufacturing by replacing the internal volume of solid blades with octet truss unit cells of variable strut thickness. Experimental and numerical vibration analyses were performed on the blades to establish their suitability for potential use in turbine blades. A maximum weight reduction of 24.91% was achieved. The natural frequencies of lattice blades were higher than those of solid blades. A stress reduction up to 38.6% and deformation reduction of up to 21.5% compared with solid blades were also observed. Both experimental and numerical results showed good agreement with a maximum difference of 3.94% in natural frequencies. Therefore, apart from being lightweight, octet-truss-lattice-based blades have excellent vibration characteristics and low stress levels, thereby making these blades ideal for enhancing the efficiency and durability of gas turbines.
Highlights
Academic Editors: Marco Mandolini, The efficiency and stability of any turbine and other high-speed rotating machinery depends on the design of their rotor systems [1]
An increase in first natural frequency is always desirable in turbines because the operating speed of rigid rotors must be lower than the first natural frequency
A maximum natural frequency of 1987.50 Hz was observed for the 0.25 mm lattice blade model, and a minimum natural frequency of 1887.50 Hz was observed for the solid blade model at the first mode
Summary
Academic Editors: Marco Mandolini, The efficiency and stability of any turbine and other high-speed rotating machinery depends on the design of their rotor systems [1]. The flow is highly unsteady, which can induce high amplitudes of blade vibration under resonant conditions [5]. These excessive resonant stresses may lead to high-cycle fatigue (HCF) failure that can subsequently result in catastrophic engine failure [6]. The blades receive a major periodic excitation at a frequency that is equal to the nozzle passing frequency Given that these forces are periodic, several harmonics must be considered to determine whether resonance takes place and whether these harmonics coincide with any natural frequency of the blade [8]
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