Centrifugal blowers have far too many applications. Automotive HVAC is one of them. Following picture demonstrates typical layout of blower inside the heating module for automobiles.
The purpose of this demonstration is:
to gain insight into the operation of a centrifugal blower, effect of casing on pressure recovery
develop an optimized throat shape, size and location
execute basic optimization using 2D simulation
use the 2D mesh to generate the 3D mesh, a novel use of mesh extrusion
assess the improvement in results using Sliding Mesh Model (SMM) over Multiple Reference Frame (MRF) model
study the effect of clearances between blade and casing on overall performance - 3D simulation
check for the issues observed when solution for SMM is initialized with a converged MRF solution vs. full transient start where flow field is uniform.
The computational domain consists of a cascade of 40 forward-curved blades rotating at 50 Hz.
The boundary condition, material properties and solver setting are
Incompressible air at 25 [C] and 1 [atm] resulting in density of 1.185 [kg/m3.
Realizable k-ε model with enhanced wall treatment
Coupled solver with 2nd order discretization schemes for mass, momentum and turbulence
The results with Shear Stress Transport (SST) turbulence model is presented in following plots.
The plots Y+, velocity contour and wall shear on top wall are shown here.
The calculated mass flow rate per unit depth of the blade is 4.72 [kg/s].
Small level of reverse flow observed near the throat area which has been handles by redesign of this section and extending the outlet. Free-slip wall boundaries can be applied to eliminate the effect of extended domain.
The location of throat is very close to the optimal design and there is no back flow into the blade cascade from the discharge region.
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