Performance prediction of Roots blower based on shape of the rotor-profile using FVM with adaptive mesh redistribution technique and GA-tuned neural network

Abstract

Attempt is made to define the shape of 2-lobe rotor-profile using three arcs. Mathematical model is proposed, and the rotor-profile is successfully parameterized in terms of two independent parameters (base and waist circle radius). Unsteady internal hydrodynamics and heat interaction of the Roots blower are captured using transient finite volume method with an adaptive mesh redistribution technique (moving mesh method) by considering different shapes of rotor-profile. At first, the present numerical scheme is validated with the results available in the literature. Spatial distribution of pressure, velocity, stream function, and temperature throughout the flow domain is extracted at different time instants considering different shapes of the rotor-profile. For better understanding, time variation in area-weighted average velocity magnitude, mass flux, and temperature at the exit port is also evaluated corresponding to each of the rotor-profiles. Transient distribution of pressure, velocity, temperature in the flow domain, leakage at the inlet, backflow at the outlet as well as the time variation in velocity, mass flowrate, and temperature at the exit port is found very sensitive to the shape of the rotor-profile. Attempt is made to establish relation between performance of the Roots blower and shape of the rotor-profile using multiple regression analysis and neurobiological computational approaches (neural network guided by parametric study and neural network tuned by genetic algorithm). Only using the indigenously developed hybrid neurobiological computational scheme with evolutionary algorithm (obtained through perfect amalgam of local search tool: backpropagation algorithm and global search tool: genetic algorithm), the said relation is perfectly captured and blower performance (in terms of discharge mass flux) is perfectly predicted (by knowing the shape of the rotor-profile).