Adam Michalson Mechanical Engineering PhD Comp Exam Presentation
- Tuesday, February 25, 2020 at 9:00am
- Barnard Hall, Room 126 - view map
Optimization of the Aerodynamic Flow of the Backward Curved Centrifugal Fan Blade Passage Using Computational Fluid Dynamics for HVAC Applications
Everyday millions of centrifugal fans are in continuous operation across the world constituting a constant draw on energy resources. These fans are an important component to modern heating, ventilation and cooling (HVAC) systems, yet they cost millions of dollars to operate every year as ventilation accounts for approximately 15% of total energy usage within the built environment ("U.S. Energy Information Administration - EIA - Independent Statistics and Analysis,"). Centrifugal fans are used because of their ability to overcome high static pressures in today’s built-environment.
The centrifugal blade passage is defined by the shape of the fan blades and the bottom and top surfaces, shroud and backplate, respectively. In practice this results in a rectangular shape from the entry of the blade passage to a rectangular outlet at the fan perimeter. When considering the blades, the width between the blades is continuously increasing as air moves towards the fan outlet. The distance between the shroud and backplate is then shaped so that the passage acts like a diffuser with a gradually increasing flow area. While blade design improvements have been shown to help the peak efficiency of the fan, this approach has a limited ability to improve the breadth of operational efficiency over a range of system pressures seen in fan systems. The shroud and backplate of centrifugal fans have traditionally been very simple in shape. However, shaping the shroud and the backplate will allow for a passage that controls the flow area more precisely and remove the sharp angles from classic construction. This will lead to inlet and outlet shapes to the blade passage that are more conducive to efficient aerodynamic flow.
This research will utilize hyperbolic curves for both the shroud and backplate as well as change the rectangular shape of the outlet to include elliptical curves along the blade passage. This will result in a shroud and backplate that are no longer pure revolutions, but will be periodic in each blade passage. In order to test new designs more efficiently, computational fluid dynamics (CFD) will be leveraged to evaluate the aerodynamic efficiency of the new blade passages. CFD provides a way to visualize the turbulent 3-D flow within the moving fan and it also allows for the collection of data that is otherwise expensive and/or impossible to collect on a real system. Once the effects of the different designs have been investigated computationally, experimental studies can be conducted to validate the most promising design. This has the potential to eliminate costly redesign phases through physical prototypes.
- Department of Mechanical & Industrial Engineering