Experimental Investigations of fans for Personal Protective Equipment

Gafaru Moro

Master's thesis

Abstract:

The need to meet certain specified requirements of fan operation has resulted in many researchers in the field of fan design to explore different design methods. This work focuses on the investigation of different fan design parameters that affect the performance of fans used in powered air-purifying respirator type. To ascertain the performance of fans in practical situations, a fan test stand was designed and manufactured. The test stand was used to experimentally measure aerodynamic parameters of the fan which include backpressure, and mass flow rate. Furthermore, experimental results were compared with theoretical 1-D model formulated by Euler, however, with losses accounted for. The parameters that were considered were mainly focused on the design of impellers with straight blades and backward curved blades. The effects of the design parameters on fan performance including blade inlet and outlet angles, blade number, rotation speed of fan, roughness of blades, and mutual position of impellers and shaft are discussed. Comparisons of performance curves using dimensionless quantities revealed that an increase in the outlet blade angle from 20° to 50° resulted in higher flow. Optimum number of blade required for this design was also investigated for impellers with 8, 12 and 16 number of blades. The effect of blade roughness, and improper assembly due to mutual position of impeller and shaft had little effect on performance. The fan operating point was observed at pressure and flow coefficients of 0.35 and 0.12, respectively when the fan was tested with a combined ABEP-R filter. In addition, impellers with backward curved blades were modified to have short blades, high number of blades, and varying blade pitch angles. The effects of these modifications on fan performance are discussed.

Abstract:

The need to meet certain specified requirements of fan operation has resulted in many researchers in the field of fan design to explore different design methods. This work focuses on the investigation of different fan design parameters that affect the performance of fans used in powered air-purifying respirator type. To ascertain the performance of fans in practical situations, a fan test stand was designed and manufactured. The test stand was used to experimentally measure aerodynamic parameters of the fan which include backpressure, and mass flow rate. Furthermore, experimental results were compared with theoretical 1-D model formulated by Euler, however, with losses accounted for. The parameters that were considered were mainly focused on the design of impellers with straight blades and backward curved blades. The effects of the design parameters on fan performance including blade inlet and outlet angles, blade number, rotation speed of fan, roughness of blades, and mutual position of impellers and shaft are discussed. Comparisons of performance curves using dimensionless quantities revealed that an increase in the outlet blade angle from 20° to 50° resulted in higher flow. Optimum number of blade required for this design was also investigated for impellers with 8, 12 and 16 number of blades. The effect of blade roughness, and improper assembly due to mutual position of impeller and shaft had little effect on performance. The fan operating point was observed at pressure and flow coefficients of 0.35 and 0.12, respectively when the fan was tested with a combined ABEP-R filter. In addition, impellers with backward curved blades were modified to have short blades, high number of blades, and varying blade pitch angles. The effects of these modifications on fan performance are discussed.

Keywords

Air-purifying respirator, dimensionless quantities, Backpressure, test stand

Language used: English

Date on which the thesis was submitted / produced: 3. 5. 2019

Thesis defence

• Supervisor: doc. Ing. Václav Dvořák, Ph.D.

Technical University of Liberec

Faculty of Mechanical Engineering

Master programme / field:
Mechanical Engineering / Machines and Equipment Design