Numerical and Experimental Analyses for the Aerodynamic Design of High Performance Counter-Rotating Axial Flow Fans

Cho, Leesang; Choi, Hyunmin; Lee, Seawook

doi:10.1115/fedsm2009-78507

Cited by 8 publications

(5 citation statements)

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“…Few pieces of research are reported in open literature concerning performance study of counter-rotating fan stage. Cho et al [1] showed that in the case of contra-rotating fan the efficiency is at its peak when the hub-to-tip ratio is 0.4, which is almost the same point for front and rear rotor maximum efficiency. Further, they have also established that the static pressure rise is higher at tip regions of the front rotor and hub regions of the rear-rotor blade considering the variation of the relative velocity.…”

Section: Introductionmentioning

confidence: 88%

Effects of Total Pressure Distribution on Performance of Small-Size Counter-Rotating Axial-Flow Fan Stage for Electrical Propulsion

Bandopadhyay

Mistry

2022

ASME Open Journal of Engineering

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Counter-rotating fan provides significant benefits over the conventional fan in terms of overall performance and size. For electric propulsion application, a counter-rotating fan provides compactness and reduction in weight to achieve higher pressure rise with less power consumption as compared to the unducted propeller. Past literature suggests counter-rotating fans, designed with higher loading in the front rotor, have a flat performance map and a wider range of stable operation. The recommendation of higher aerodynamic loading is not clear what needs to be the aerodynamic load split amongst the rotors. This, in particular, benefits the electrical vehicle to have higher maneuver capability during operation. The paper discusses the design methodology of counter-rotating fans for application in roadable electric aircraft and the effect of different aerodynamic load distributions for both rotors on its overall performance. Fans are designed for different total-pressure rise and loading distributions as (1) 50–50%, (2) 55–45%, (3) 60–40%, and (4) 65–35% in front and rear rotor. It is observed that, as the loading increases for the front rotor, blade camber increases and hence to more prone toward flow separation near the trailing edge under an adverse pressure gradient. Wake coming from the front rotor grows thicker with higher loading, leading to flow acceleration (thus total-pressure loss) in the axial gap between these rotors. As a consequence, flow incidents on the rear rotor other than the design incidence, and thus the rear rotor operates under off-design. With 55–45% loading, both the rotors achieve desired total-pressure rise and stable operating range. The detailed flow field study is discussed to bring important outcomes for achieving the desired performance.

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Section: Introductionmentioning

confidence: 88%

Effects of Total Pressure Distribution on Performance of Small-Size Counter-Rotating Axial-Flow Fan Stage for Electrical Propulsion

Bandopadhyay

Mistry

2022

ASME Open Journal of Engineering

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“…Among the few studies dedicated to the design procedure of a counter-rotating stage one can cite the works of Cho et al [14] who use a conventional design method based on the simplified meridional flow method with the radial equilibrium equation and the free vortex design con-dition, and study the effect of parameters such as the hub to tip ratio, or the solidity. Cao et al [15] used Computational Fluid Dynamics results to re-design the rear rotor of a counter-rotating pump and obtain an increase in performances with respect to the original rear rotor conventional design.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on the effect of load distribution on the performances of a counter-rotating axial-flow fan

Ravelet

Bakir

Sarraf

et al. 2018

Experimental Thermal and Fluid Science

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In the design procedure of a counter-rotating axial-flow stage, parameters such as the angular velocity ratio and the repartition of the work performed by each rotors are to be chosen. In the present Article, three counter-rotating stages are designed to meet the same working point. These stages have different repartitions of load between the front and rear rotor, different angular velocity ratios or mean stagger angles of the blades of the front rotors. The stage global characteristics and the unsteady features of the flow between the counter-rotating rotors are measured and compared. The three systems all have satisfying overall performances at the design point. Strong differences are observed in the flow field at partial flow rates, the rear rotor reducing the hub recirculation. The behaviour at partial flow rates is thus triggered by the rear rotor characteristics. The best compromise is obtained with a repartition of the loading of 60% for the front rotor and 40% for the rear rotor, with almost equal angular velocities.

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“…The results showed larger pressure rise and efficiency with lower rotation rate at a given power consumption. Cho et al 4 showed how to design rotor blades and Wang et al 5 investigated different blade pitch angles to validate and improve recommendations for shaft power matching of CRFs. Another focus has been on the reduction of sound emission, see Shin et al 6 and Li et al 7 Grasso et al 8,9 focused on the reduction of the mechanical stresses and broadband noise scattered from the trailing-edge of the blades.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical investigation of a gearless one-motor contra-rotating fan

Heinrich

Friebe

Schwarze

2016

Proceedings of the Institution of Mechanical Engineers, Part A:

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A gearless one-motor concept for contra-rotating fans is presented in this article. The rotors are mounted to an electric motor using only one shaft. The coupling between both rotors is realised by utilising the conservation of angular momentum. The contra-rotating fans has a diameter of 200 mm at a design speed of 2100 min À1 for the first stage and 1200 min À1 for the second stage. It has been designed and investigated through a series of experiments by the Institute of Air Handling and Refrigeration in Dresden. The performance map and 2D particle image velocimetry measurements have been conducted. Numerical models for 3D quasi-steady state and transient simulations have been implemented and carried out by the Institute of Mechanics and Fluid Dynamics. The results show a good agreement between the quasi-steady, the transient simulations and the experiment. However, when close to stall, the time-resolved simulations show a superior performance compared with steady-state computations.

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Numerical and Experimental Analyses for the Aerodynamic Design of High Performance Counter-Rotating Axial Flow Fans

Cited by 8 publications

References 0 publications

Effects of Total Pressure Distribution on Performance of Small-Size Counter-Rotating Axial-Flow Fan Stage for Electrical Propulsion

Effects of Total Pressure Distribution on Performance of Small-Size Counter-Rotating Axial-Flow Fan Stage for Electrical Propulsion

Experimental investigation on the effect of load distribution on the performances of a counter-rotating axial-flow fan

Experimental and numerical investigation of a gearless one-motor contra-rotating fan

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