Impact of internal lattice structures on the weight and natural frequencies of a low pressure turbine blade

Abstract

Vibration characteristics play a crucial role in the overall performance of Low-pressure (LP) turbine blades and different techniques are developed to enhance vibrational response by increasing natural frequencies. The present analysis aims to develop a new technique based on the investigation of improvement in natural frequencies and mass reduction of a topology-optimized blade design through location-based integration of lattice structures inside the blades. FE models are developed for three different lattice locations based on mode shape behavior obtained through modal analysis of two different nickel-based alloys at stressed and unstressed conditions. The results show that the internal BCC lattice at specific locations showed better vibrational characteristics compared to other incorporated lattice structures, and validates the location-based integration scheme for enhancement of natural frequencies and reduced mass in applied conditions. By this method, 5.7% mass reduction was achieved from an already 35% mass-reduced blade along with enhancement in the first and second natural frequencies by 8.2% and 5.9% respectively when unstressed. At stressed condition, the natural frequencies increased by ≈7.7% and ≈6.6%.