CFD Analysis of Compressor Rotor Used in Turbo Machineries and Optimization of Manufacturing Process Parameters

Abstract

The present work is conducted to study and enhance the current understanding of axial compressor of a jet engine. Two different domains of studies are conducted on transonic axial compressor rotor. NASA Rotor 37 is selected for analysis. In the first study, which is CFD study, literature is reviewed extensively to validate the results first. Steady State analysis is performed at design speed. Once validation has been completed, aerodynamic optimization is carried out on the present case by inclusion of tubercle on transonic axial compressor rotor. This method of optimization has not been observed in the past thus it is the novelty of the present work. Detailed procedure of creating tubercle on rotor is discussed. Optimization results reveal an increase in efficiency which is maintained for the entire operating range. Moreover, drop in efficiency near choke condition is reduced significantly meaning improved performance. The increase in efficiency is due to greater pressure at outlet in optimized case. Greater pressure at outlet is credited to modification in shockwave pattern in optimized case in which intensity of shockwave is weakened throughout the shockwave passage. Secondly, the shockwave has modified from normalbiased shockwave to oblique-biased shockwave. Oblique being less detrimental is evident for reduction in aerodynamic loss. Finally, generation of vortices is seen near suction side of tubercle model near mid of chord. Vortices are themselves a source of loss , but they have redirected the surrounding flow in axial direction resulting in a net effect that reduce the overall losses. The second study is the manufacturing study. In this study, firstly the literature on manufacturing processes and manufacturing process parameters is reviewed. As compressor blades are mostly machined in 5-axis CNC machines, therefore, CAM software is widely used for simulating toolpaths for complex turbo machinery components. In present case, single blade is created using coordinate data file and a complete Blisk is formed by patterning it. Then toolpath is generated in MasterCAM software using the ‘Blade Expert’ and ‘Swarf Milling’ add-on features for roughing and finishing operations of blade, respectively. MasterCAM simulation feature is used to check for any tool collision for the generated toolpath. Different toolpath generation strategies are studied to determine the best one in terms of taking least machining simulation time. Results reveal that ‘offset from Hub’ strategy is the most suitable. Moreover, zigzag and one-way toolpath patterns are simulated against different feed rates which show that the zigzag pattern is optimum for blade roughing operation.