Condensed Report Cfd

Vacuum Cleaner – Acoustic Analysis

1

Objective

The objective of this Acoustic study through CFD analysis is to determine the loudness ranking of a vacuum cleaner part for various design options.

2 2

Extracted Fluid Domain

Large-Radius

Flat

Middle-Radius

Small-Radius

Flat-Rib 3 3

Extracted Fluid Domain (cont…)

Channel-1

Channel-2

Straight

Channel-3

4 4

Velocity Streamlines

Large-Radius

Flat (reverse flow observed @ outlet)

Middle-Radius

Small-Radius

Flat-Rib

5 5

Velocity Streamlines

Channel-1

Channel-2

Straight

Channel-3

6 6

Distribution of Acoustic Power (dB)

Large-Radius

Middle-Radius

Flat

Small-Radius

Flat-Rib

7 7

Distribution of Acoustic Power (dB)

Channel-1

Channel-2

Channel-3

Straight 8 8

Loudness Comparison Tables Vacuum Cleaner–I Project Loudness Ranking using CFD

Sr. No.

Geometry Name

Total Acoustic Power (W)*

1

Large-Radius

1.01 e -10

5

2

Middle-Radius

1.66 e -10

3

3

Small-Radius

1.26 e -10

4

4

Flat

30.2 e -10

1 (Loudest)

5

Flat-Rib

4.16 e -10

2

(based on Total Acoustic Power, W)

Vacuum Cleaner–II Project Loudness Ranking using CFD

Sr. No.

Geometry Name

Total Acoustic Power (W)*

1

Channel-1

2.64 e -10

2

2

Channel-2

2.77 e -10

1 (Loudest)

3

Channel-3

1.93 e -10

3

4

Straight

1.62 e -10

4

(based on Total Acoustic Power, W)

* For details please refer appendix A 9

Appendix-A 1. Following is the Proudman’s Formula# to calculate Acoustic Power per unit volume : P (W/m3) = 0.1*ρ *ε*{√(2*k)/c}5

2. This Acoustic Power can be converted into dB unit using following relation & same is plotted in slide#5 : P (dB) = 10*log10 {P (W/m3) / Pref}

where Pref = 1e-12 W/m3

3. Taking Volume Integral of P (W/m3), total Acoustic Power Generation for respective Geometry can be determined. This calculation can be done in CFX-Post. This variable can be used to compare loudness among various geometries. where ρ – density ε – kinetic energy dissipation k – kinetic energy c – sound speed Pref – Reference Acoustic Power (W/m3)

The Proudman's formula gives an approximate measure of the local contribution to total acoustic power per unit volume in a given turbulence field. #

10