Analysis of aerodynamic noise generated from inclined circular cylinder

Abstract

Making clear the generation mechanism of fluid dynamic noise is essential to reduce noise deriving from turbomachinery. The analysis of the aerodynamic noise generated from circular cylinder is carried out numerically and experimentally in a low noise wind tunnel. In this study, aerodynamic sound radiated from a circular cylinder in uniform flow is predicted numerically by the following two step method. First, the three-dimensional unsteady incompressible Navier-Stokes equation is solved using the high order accurate upwind scheme. Next, the sound pressure level at the observed point is calculated from the fluctuating surface pressure on the cylinder, based on modified Lighthill-Curl's equation. It is worth to note that the noise generated from the model is reduced rapidly when it is inclined against the mean flow. In other words, the peak level of the radiated noise decreases rapidly with inclination of the circular cylinder. The simulated SPL for the inclined circular cylinder is compared with the measured value, and good agreement is obtained for the peak spectrum frequency of the sound pressure level and tendency of noise reduction. So we expect that the change of flow structures makes reduction of the aerodynamic noise from the inclined models.

Experimental study of the aerodynamic noise radiated by cylinders with different cross-sections and yaw angles

“…However, the results of King and Barsikow [21] are closer to the trend obtained using γ = 6. The results are also compared with those obtained by Yamada et al [19] and Haramoto et al [20] for an inclined circular cylinder after being corrected by cylinder length by applying Eq. According to the independence principle the SPL should reduce more rapidly for higher yaw angles.…”

“…For the circular cylinder, Figure 7 The results in Figure 7(a) are compared with those obtained by Yamada et al [19], by King and Barsikow [21] and by Haramoto et al [20] who measured the vortex shedding noise from circular cylinders for a similar Reynolds number range as that covered in the present investigations (see Table A.1 and Table A The reason that the present results are lower than those found in the literature could be that the aspect ratio L/D used in the current experiments is not high enough to allow the end effects to be neglected. Gowda found that the threedimensional flow produced by the cylinder free ends affected the Strouhal number of the vortex shedding produced by a circular cylinder in an air flow [33].…”

“…Reynolds number Re Aspect ratio (L/D) Circular cylinder Yamada et al [19] 1.4 × 10 4 − 2.8 × 10 4 end-plates Haramoto et al [20] 1.4 × 10 4 end-plates King and Barsikow [21] 6.7 × 10 4 25 (free-end) Square cylinder Yamada et al [19] 1.4 × 10 4 − 2.8 × 10 4 end-plates King and Barsikow [21] 1.0 × 10 5 25 (free-end) Tamura and Miyagi [34] 3.0 × 10 4 end-plates Knisely [10] 2.2 × 10 4 − 6.2 × 10 4 end-plates Elliptical cylinder Modi and Wiland [12] 2.4 × 10 4 − 1.0 × 10 5 end-plates Modi et al [13] 3.0 × 10 4 − 1.0 × 10 5 end-plates Fujita [35] 1.7 × 10 4 end-plates King and Pfizenamier e = 0.72 [14] 9.5 × 10 4 16 and 25 (free-end) King and Pfizenamier e = 0.86 [14] 1.0 × 10 5 16 and 25 (free-end) Rectangular cylinder Knisely [10] 7.2 × 10 2 − 8.1 × 10 4 end-plates King and Pfizenamier [14] 9.9 × 10 4 and 1.4 × 10 5 16.7 (free-end)…”

Experimental investigation of flow-induced sound of kite lines

“…Latorre Iglesias et al [14] assessed the effect of the angle of attack and flow speed on the aerodynamic cylinder noise and compared his results to the experimental studies of Yamada et al for AOA up to 45° [15], Haramoto et al up to 40° [16] and King and Barsikow up to 30° [17]. In a Reynolds range of 15.500 5 Re 5 39.000 and for 30°5 AOA 5 90°he found that amplitude and frequency of the aeolian tone and the overall sound pressure level decrease with declining AOA while the bandwidth of the spectral peak increases.…”

Effect of aspect ratio on aerodynamic sound generated from inclined circular cylinder

“…When a wind tunnel experiment is carried out with endplates, the sounds emitted from inclined circular cylinder depend on the diameter of the circular cylinder 1 . The objective of this paper is to clarify that phenomenon by both experiment (measurement of the sounds) and numerical simulation.…”