Flow characterization of centrifugal blower systems and development of new design features to improve its performance

Flow characterization inside automotive air-handling blower systems of “standard designs” was performed by computational fluid dynamic (CFD) analysis, airflow and sound testing, and Laser Doppler Velocimetry (LDV). A low speed Rotating Machinery “Resolver” (RMR) was used to measure velocity components inside fan blade channels. Initial analyses defined major flow circulation inside blower scrolls and flow separation from centrifugal fan blades. A strategy of resolving the major flow deficiencies was established.; A literature survey of turbo-machinery design considerations and field concerns, was conducted. Major similarities and differences with respect to automotive blower design aspects are summarized.; A design criteria of fan blades is developed to eliminate or minimize airflow separation from blades' suction sides and leading edges. Design of experiments (DOE) techniques are employed to define the effect of scroll design parameters on blower systems airflow and noise performance. New design features of blower scrolls are developed to resolve flow circulation inside its cross sections. The new designs are evaluated and bench-marked against “standard designs”.; Flow characterization is repeated for a concept blower of the new design. Two-channels LDV and RMR experimental results are compared to three-dimensional computational analysis of the test set-up; airflow patterns are described. A number of CFD boundary conditions are discussed. Velocity profiles inside scroll cross sections, at its mid-section normal to the fan axis, and within fan blade channels are compared. CFD data agrees with tangential velocity profiles, and are similar but under-estimate radial velocities.; A new apparatus is developed to guide an amount or air flowing axially at a blower inlet to flow in radial direction with desired whirl before approaching the fan blades. Apparatus' design parameters are disclosed, and optimized by DOE for an automotive air-handling system.; The new developments result in airflow rates increase through automotive blowers' operating range to exceed the rates of the next higher size “standard designs.” Blower efficiencies are increased 7 to 15%, while power consumption is reduced by 7 to 15%. Blower acoustic pressures are lowered by 17 to 50%, and its overall sound pressure levels are reduced by 2 to 5 “A weighted” decibels....