Analytical and numerical investigation of the optimum pressure distribution along a low-pressure axial fan blade

Abstract

Abstract:In the field of axial flow turbomachines, the two-dimensional cascade model is often used experimentally or numerically to investigate fundamental flow characteristics and overall performance of the impeller. The core of the present work is a design method for axial fan cascades aiming to derive inversely the optimum blade shape based on the requirements of the impeller and not using any predefined aerofoil profiles.While most design strategies based on the aerofoil theory assume constant total pressure at all streamlines, i.e. free-vortex flow, this paper investigates the possibility of varying the total pressure along the blade and based on that, an analytical expression of the outlet blade angle is determined. When computing the blade profile at a specified radius, critical parameters reflecting on the flow characteristics are observed and adjusted (i.e. sufficient lift and controlled deceleration of the flow on the contour) so that the resulting profile is derived for minimum losses.The validation of this design strategy is given by the numerical results obtained when employed as an optimization tool for an industrial fan: 10-20 per cent absolute increase in the static efficiency of the optimized impeller.

The Effects of Inlet Box Aerodynamics on the Mechanical Performance of a Variable Pitch in Motion Fan

“…The improved eight stay plus eight inlet guide vane configuration increases the fan aerodynamic loading. Increasing fan aerodynamic loading also increased fan acoustic emissions [12]. When we analyze the improved eight stay plus eight inlet guide vane configuration using Pascu et al's method [12], we can predict an overall increase in fan acoustic emissions of between 3 and 5 dB.…”

“…Increasing fan aerodynamic loading also increased fan acoustic emissions [12]. When we analyze the improved eight stay plus eight inlet guide vane configuration using Pascu et al's method [12], we can predict an overall increase in fan acoustic emissions of between 3 and 5 dB. In practice, the author installed the original configurations and then later retrofitted the improved configuration into the same fan.…”

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“…The fan efficiency (η) can be written as the ratio of hydraulic power (P hydraulic ) and the shaft power (P shaft ) as seen in Eq. ( 7) [28]. The hydraulic power is the multiplication of the volume flow rate (Q) and the total pressure difference (P) at the fan cover inlet and outlet (Eq.…”

Multi-Objective Optimization for the Radial Bending and Twisting Law of Axial Fan Blades

“…Li et al [1] investigated the performance change of axial fans with impeller trimming quantities of 5%, 10%, and 15% of the blade height. Pascu et al [2] optimized the blade profile by the three-dimensional inverse method to achieve the minimum loss in an axial fan. Ye et al [3] designed several blade tip patterns to explore the relationship between the shape of the groove tip and leakage losses.…”