# A CFD Results-Based Approach to Investigating Acoustic Attenuation Performance and Pressure Loss of Car Perforated Tube Silencers

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Methods

#### 2.1. Mesh Mapping

- Number of nodes (N): The maximum number of nodes from the source mesh that are considered for mapping with one node of the target mesh.
- Maximum distance (R): Only the nodes of the source mesh that lie inside a sphere with a radius R—centered at the node of the target mesh—are taken into account.

_{1}and W

_{2}are the acoustic power of the inlet and outlet of the silencer, respectively; p

_{1}and p

_{2}are the sound pressure of the incident and the transmitted waves, respectively; $\overline{{p}_{1}}$ and $\overline{{p}_{2}}$ are conjugate complex numbers of ${p}_{1}$ and ${p}_{2}$, respectively; Z

_{1}and Z

_{2}are the acoustic impedance of the inlet and outlet of the silencer, respectively; and A

_{1}and A

_{2}are the cross-sectional areas of the inlet and outlet of the silencer, respectively.

#### 2.2. Method Validation

_{1}= l

_{2}= 128.6 mm; each tube is perforated with 160 orifices, with a porosity of 3.9%, a diameter of 2.49 mm; and a wall thickness of 0.81 mm.

## 3. Modeling and Steady Computation Using CFD

#### 3.1. Modeling

#### 3.2. The CFD Results

#### 3.3. Pressure Loss Calculation

## 4. Sound Field

#### 4.1. Check the Maximum Frequency Value of the Acoustic Mesh

#### 4.2. Effects of Temperature Changes on the TL of the Silencer

#### 4.3. Effects of Flow Velocity Changes on the TL of the Silencer

## 5. Conclusions

## Acknowledgments

## Author Contributions

## Conflicts of Interest

## References

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**Figure 4.**Comparison of the predicted and measured transmission loss (TL) for the straight-through perforated tube silencer (Mach number M = 0.1, Temperature T = 288 K): (

**a**) Pattern 1; (

**b**) Pattern 2.

**Figure 6.**Comparison of the calculated and measured TL for the cross-flow silencer (v = 17 m/s, T = 374 K).

**Figure 7.**3D geometrical model for the three-pass perforated tube silencer: (

**a**) structural model; (

**b**) flow field model.

**Figure 8.**Mesh model for the three-pass perforated tube silencer: (

**a**) computational fluid dynamics (CFD) mesh model; (

**b**) acoustic mesh model.

**Figure 13.**The selected points for the total pressure calculation in the cross sections of the inlet and outlet of the silencer.

**Figure 14.**The sound pressure level of the inlet and outlet of the silencer (v = 55 m/s): (

**a**) T = 760 K; (

**b**) T = 560 K; (

**c**) T = 960 K.

**Figure 15.**Effects of temperature on the TL of the silencer (v = 55 m/s) : (

**a**) 760 K versus 560 K; (

**b**) 760 K versus 960 K.

**Figure 16.**The sound pressure level of the inlet and outlet of the silencer (T = 760 K): (

**a**) v = 20 m/s; (

**b**) v = 35 m/s.

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**MDPI and ACS Style**

Zhang, H.; Fan, W.; Guo, L.-X.
A CFD Results-Based Approach to Investigating Acoustic Attenuation Performance and Pressure Loss of Car Perforated Tube Silencers. *Appl. Sci.* **2018**, *8*, 545.
https://doi.org/10.3390/app8040545

**AMA Style**

Zhang H, Fan W, Guo L-X.
A CFD Results-Based Approach to Investigating Acoustic Attenuation Performance and Pressure Loss of Car Perforated Tube Silencers. *Applied Sciences*. 2018; 8(4):545.
https://doi.org/10.3390/app8040545

**Chicago/Turabian Style**

Zhang, Hao, Wei Fan, and Li-Xin Guo.
2018. "A CFD Results-Based Approach to Investigating Acoustic Attenuation Performance and Pressure Loss of Car Perforated Tube Silencers" *Applied Sciences* 8, no. 4: 545.
https://doi.org/10.3390/app8040545