A Numerical Investigation to Capture the Unsteady Internal Flow Phenomena and Heat Transfer Mechanism in Roots Type Blower or Pump

Abstract

An attempt is made to capture the unsteady internal flow phenomena and heat transfer mechanism in a root blower using numerical simulation (using FVM) and to optimize the rotor profile of the root blower/pump for increasing the volumetric efficiency, minimizing the noise and reducing the exhaust temperature. The objectives of the present work are: (i) To study the lobe profile of a roots blower/pump and vary the lobe profile to get the optimum flow rate and outlet temperature. (ii) To capture the unsteady (dynamic) internal flow phenomena and heat transfer mechanism using adaptive mesh redistribution technique.

A two-lobe root blower is considered here where, the rotor-geometry is formed by combination of three arcs. The mouth (or waist) part is a circular arc, the upper portion of the lobe is also circular and the arc connecting them is involute.

The obtained results first validated with the existing literature (Li et al., 2013). Variation of outlet parameters (Outlet mass flow rate, outlet velocity, outlet temperature) with time have been studied. Velocity vector and stream lines have been plotted for different time-instance. Effect of rotational speed on outlet mass flux, outlet velocity, outlet temperature have been studied.