Topology design of reactive mufflers for enhancing their acoustic attenuation performance and flow characteristics simultaneously

Abstract

SUMMARY When seeking to enhance the acoustic attenuation performance of a reactive muffler, it is necessary to ensure that the flow resistance does not increase significantly. To date, there have been very few attempts to simultaneously optimize the transmission loss and pressure drop of a muffler. In this study, a multiobjective topology optimization problem is formulated to maximize the transmission loss at a target frequency and minimize the pressure drop simultaneously. The objective function in the formulation is given as the sum of weighted transmission loss and weighted pressure drop. The effect of the weighting factors on the optimal topologies of a muffler is investigated. Furthermore, the physical interpretation of partition layouts of optimized mufflers is discussed. The proposed muffler design method involving multiobjective topology optimization is compared with the previous muffler design method that involves single‐objective topology optimization to maximize only the transmission loss. The most important advantage of this study is shown by considering numerical results; the proposed muffler design method is applicable to nonconcentric expansion chamber mufflers, unlike the previous muffler design method. Copyright © 2012 John Wiley & Sons, Ltd.

Optimum core design to improve noise attenuation performance and stiffness of sandwich panels used for high-speed railway vehicles

“…Figure 9 compares the optimized topologies depending on the target frequency for α = 1.3: TL opt = 5.20 dB from TL ini = 1.64 dB at f t = 100 Hz, TL opt = 19.71 dB from TL ini = 16.85 dB at f t = 125 Hz, TL opt = 54.66 dB from TL ini = 48.87 dB at f t = 200 Hz, and TL opt = 44.16 dB from TL ini = 43.57 dB at f t = 250 Hz. These results imply that the optimal topology for the TL maximization was significantly affected by the target frequency, consistent with prior studies (Lee and Kim 2009;Lee and Jang 2012). However, the effect of α on the optimal topology was almost negligible.…”

“…This method requires sensitivity analysis of the compliance and TL with respect to each design variable. Equations (20) and (21) were used in the topologyoptimization problems (Lee and Jang 2012;Sigmund 2001). The differentiations of the acoustic pressure at three points with respect to each design variable were calculated using the formulation suggested by Lee and Kim (2009).…”

Optimal topology of reactive muffler achieving target transmission loss values: Design and experiment

“…To this end, the interpolation function should be carefully selected, and the choice of Eqs. (11a) and (11b) has been validated in several acoustical topology optimization problems [22,24,27,31].…”

“…Since rigid body elements form rigid partitions, the objective function suitably represents the first design goal of minimizing the partition volume. In addition, since the TL value at a target frequency decreases as the number of rigid body elements decreases [27,31], one inequality condition for a TL value at each target frequency suitably represents the second design goal of achieving the target TL value.…”

Three-Dimensional Aeroacoustic Numerical Simulation of Flow Induced Noise of Mufflers

“…However, flow in the duct and chamber of muffler is commonly unsteady, complex and turbulent, which generates noise by itself. The flow induced noise should be carefully considered for design and optimization of the muffler, especially at high speed [1][2][3][4][5][6].…”