Experimental and Numerical Investigation of a 60cm Diameter Bladeless Fan

Jafari, Mohammad; Afshin, Hossein; Farhanieh, Bijan; Bozorgasareh, Hamidreza

doi:10.18869/acadpub.jafm.68.225.24081

Cited by 15 publications

(4 citation statements)

References 23 publications

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“…35 In the literature these sorts of appliances are referred to as ventilated open core annular jets (OCAJ). [36][37][38] Figure 2 shows the general concept. Air is pumped into a ring with a hollow interior that acts as a plenum chamber.…”

Section: A Ventilated Open Core Annular Jetmentioning

confidence: 99%

The vortex ring state of a rotor and its comparison with the collapse of an annular jet in counterflow

2023

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The vortex ring state (VRS) of a rotor is associated with the development of the trailed vortex system in powered descending flight, where the topology of the vortex wake changes from its usual helical form into a toroidal form. In the VRS the toroidal vortex ring envelops the entire rotor, and it sheds and reforms in an unsteady manner. In previous attempts to understand the basic phenomenology of the VRS, the focus was on the role of the trailed vortices in the transition to the VRS: computational and experimental work utilised rotor models to generate the trailing vortex wake, and mechanisms for the emergence of the VRS were postulated based upon the interaction of the trailed vortices. In this paper a different approach is taken: a set of experiments on a core annular jet flow are described, where the jet flow in counterflow is used to simulate a rotor in powered descent. It is shown that this leads to the formation of a flow field that shares many of the features of the VRS of a rotor system. This brings into question the role of the rotor blade trailing vortices in the development of the rotor wake VRS, and it is proposed instead that the interaction between the mean flow and counterflow drives the VRS phenomenon.

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Section: A Ventilated Open Core Annular Jetmentioning

confidence: 99%

The vortex ring state of a rotor and its comparison with the collapse of an annular jet in counterflow

2023

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“…Very few studies have been conducted on Bladeless fans using CFD. [2,3] Conducted an experimental and numerical analysis on bladeless fans by changing parameters such as the fan cross-section height, flow outlet angle relative to the fan axis, hydraulic diameter, and aspect ratio. CFD analysis identified that the discharge ratio is maximum for a crosssectional height of 3 cm and an outlet angle of 16 • .…”

Section: Literature Surveymentioning

confidence: 99%

Determination of Optimum Outlet Slit Thickness and Outlet Angle for the Bladeless Fan Using CFD

Joshi¹,

Noronha²,

Vinayagamurthy³

et al. 2022

Preprint

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Toshiba devised the bladeless fan (or Air Multiplier) concept in 1981. Researchers like James Dyson and Jafari et al. further developed it. Bladeless fans are more energy-efficient, safer due to the hidden blades, easier to clean, and more adjustable than conventional fans. From a performance point of view, bladeless fans are better because they multiply mass flow rate, eliminate buffeting, consume less power, and are quieter. This paper investigates the influence of the airfoil’s outlet slit thickness on the discharge ratio by varying the outlet slit thickness of an Eppler 473 airfoil from 1.2 mm to 2 mm in intervals of 0.2 mm. Results indicated that smaller slits showed higher discharge ratios. The airfoil with a 1.2 mm slit thickness showed a discharge ratio of 18.78, a 24% increase from the discharge ratio of the 2 mm slit. The effect of outlet angle on the pressure drop across the airfoil was also studied. Outlet angles were varied from 16∘ to 26∘ by an interval of 2∘. The airfoil profile with a 24∘ outlet angle showed a maximum pressure difference of 965 Pa between the slit and leading edge. In contrast, the 16∘ outlet angle showed the least pressure difference of 355 Pa. Parameters such as average velocity, turbulent kinetic energy, the standard deviation of velocity and outlet velocity magnitude was used to assess the performance of airfoil profiles used in bladeless fan.

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“…When the flow rate increases gradually, the hydraulic loss of the impeller increases with the increased blade outlet angle. Mohammad et al 10 designed and manufactured a vaneless fan with a diameter of 60 cm to explore the feasibility of its application in large-scale industries. Tan et al 11 investigated the pressure difference between the inlet and outlet, air volume, and efficiency.…”

Section: Introductionmentioning

confidence: 99%

Blade shape optimization and internal-flow characteristics of the backward non-volute centrifugal fan

Zhang

Wang

Yang

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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The work proposed the double parameter optimization method of the non-volute centrifugal fan’s blade profile based on the steepest descent method. Total-pressure efficiency improvement at the high-flow area was taken as an optimization objective. A method of applying the steepest descent method to modify the blade profile of backward centrifugal fan is proposed in this paper. The gradient descent direction was analyzed to design the blade profile and obtain the optimal blade profile at a high-flow rate. Besides, numerical simulations were carried out to analyze the aerodynamic performance and the internal flow characteristics of the centrifugal fan by the computational fluid dynamics method. Numerical results showed that the blade profile along the gradient descent was optimized to effectively increase the total pressure and the total pressure efficiency of the original model at the high-flow rate. The steepest descent method for local optimization could improve the fan blade design.

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Experimental and Numerical Investigation of a 60cm Diameter Bladeless Fan

Cited by 15 publications

References 23 publications

The vortex ring state of a rotor and its comparison with the collapse of an annular jet in counterflow

The vortex ring state of a rotor and its comparison with the collapse of an annular jet in counterflow

Determination of Optimum Outlet Slit Thickness and Outlet Angle for the Bladeless Fan Using CFD

Blade shape optimization and internal-flow characteristics of the backward non-volute centrifugal fan

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