Abstract
Measurements have been made in an automotive HVAC blower for two different centrifugal fans. This work is directed at improving the performance of a conventional forward-curved centrifugal fan for a given small blower casing. Mean velocities and pressure have been measured using a miniature five-hole probe and a pressure scanning unit connected to an online data acquisition system. First, we obtained the fan performance curves versus flow rates showing a significant attenuation of unstable nature achieved with the new fan rotor in the surging operation range. Second, aerodynamic characterizations were carried out by investigating the velocity and pressure fields in the casing flow passage for different fan operating conditions. The measurements showed that performance coefficients are strongly influenced by flow characteristics at the throat region. The main flow features were common in both fans, but improved performance is achieved with the new fan rotor, particularly in lower flow rate regions. Based on the measured results, design improvements were carried out in an acceptable operation range, which gave considerable insight into what features of flow behavior were most important.
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Abbreviations
- b:
-
Rotor width
- B:
-
Casing width
- c:
-
Blade chord length
- C:
-
Cut-off clearance
- Cp :
-
Pressure coefficient for calibration
- Cpw :
-
Casing wall pressure coefficient
- Ct :
-
Reference pressure coefficient for data validation
- Cv :
-
Velocity coefficient for calibration
- Do :
-
Casing inlet opening diameter
- D1, D2 :
-
Rotor inlet and outlet diameter
- N:
-
Number of blades
- p:
-
Static pressure
- pt :
-
Total pressure
- Pshaft :
-
Rotor shaft power
- q:
-
Dynamic pressure
- Q:
-
Volume flow rate
- r,θ s , Z:
-
Cylindrical coordinates (Fig. 1)
- Rs :
-
Scroll radius
- Re:
-
Reynolds number
- S:
-
Blade pitch
- U:
-
Blade speed
- V:
-
Flow velocity
- α s :
-
Scroll angle
- β:
-
Blade angle
- η:
-
Total fan efficiency
- ϕ:
-
Nondimensional flow coefficient
- ν:
-
Kinematic viscosity
- π:
-
Density
- ψ:
-
Nondimensional total pressure coefficient
- 1,2:
-
Rotor inlet, outlet or blade tip
- 1, 2, 3, 4, 5:
-
Holes of five hole probe (Fig. 3) amb. ref: Ambient, reference conditions
- av, max:
-
Average, maximum
- C, R:
-
Casing, rotor
- e, i:
-
Entrance, inlet locations of pressure probe (Fig. 10)
- r, t:
-
Radial, tangential velocity components
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Kwon, EY., Cho, NH. Experimental study on the mean flow characteristics of forward-curved centrifugal fans. KSME International Journal 15, 1728–1738 (2001). https://doi.org/10.1007/BF03185127
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DOI: https://doi.org/10.1007/BF03185127