Open Access
Table 5.
Configuration of the airflow resistivity of each layer of materials with different gradient layers.
| Airflow resistivity | Three-layer gradient | Four-layer gradient | Five-layer gradient | Six-layer gradient |
|---|---|---|---|---|
| (N⋅s/m4) | structure | structure | structure | structure |
| First layer | 11 600 | 11 600 | 11 600 | 11 600 |
| Second layer | 26 600 | 21 600 | 19 100 | 17 600 |
| Third layer | 41 600 | 31 600 | 26 600 | 23 600 |
| Fourth layer | 41 600 | 34 100 | 29 600 | |
| Fifth layer | 41 600 | 35 600 | ||
| Sixth layer | 41 600 |
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