Development of Mixed Flow Fans with Bio-Inspired Grooves

Abstract

Mixed flow fan is a kind of widely used turbomachine, which has faced problems of further performance improvement in traditional design methods in recent decades. Inspired by the microgrooves such as riblets and denticles on bird feathers and shark skins, we here propose biomimetic designs of various blades with the bio-inspired grooves, aiming at the improvement of the aeroacoustic performance. Based on a systematic study with computational fluid dynamic analyses, we found that these designs had the potential in noise suppression even with macroscopic grooves. Our best design can suppress turbulence kinetic energy by approximately 38% at the blade leading edge with aerodynamic efficiency loss of only 0.3 percentage points. This improvement is achieved by passive flow control. The vortical structures are changed in a favorable way at the leading edge due to the grooves. We believe that these biomimetic designs could provide a promising future of enhancing the performance of mixed flow fans by making grooves of ideal flow passages on the suction faces of blades in accord with the theory of pump design.

Aeroacoustic characteristics of owl-inspired blade designs in a mixed flow fan: effects of leading- and trailing-edge serrations

“…Figure 3(a) illustrates the experimental setup comprising various testing facilities conforming to the instructions of JIS (Japan Industrial Standard) B8330. More details of the experimental methods can be found in Wang et al [47]. Here, the aerodynamic efficiency is given by,…”

Thriving artificial underwater drag-reduction materials inspired from aquatic animals: progresses and challenges

“…The structure of spanwise riblet inspired by sharkskin has been applied to simulate the hydrodynamic noise of the three-dimensional (3D) hydrofoil and the maximum noise reduction was observed at 7.28 dB. 84 The blade bionic groove design proposed by J. Wang, Nakata, and Liu 203 was applied to the mixed flow fan and it was found that the use of the groove structure has the potential to suppress noise. When the aerodynamic efficiency loss is only 0.3 percentage points, the blade leading edge reduces the turbulent flow energy by about 38%.…”

The Effects of Grid Accuracy on Flow Simulations: A Numerical Assessment

“…The high-order compact flow solver was implemented in which the grid was generated through three different methods, including the standard second-order method, the compact scheme, and the Theodorsen technique. The distributions of pressure coefficient C p = 2(p − p ∞ )/ρu 2 ∞ and skin friction coefficient C f = 2τ w /ρu 2 ∞ on the airfoil surface are respectively represented in Figure 11a,b for the subsonic, laminar flow (see, for example, [49][50][51]) with Ma = 0.5 and Re = 10 × 10 3 . The fourth-order compact grid generation method shows improvements in both pressure and skin friction coefficients compared to the second-order method and presents an excellent agreement with those results obtained from the Theodorsen grid generation technique.…”