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The paper examines the door sealing cavities near the B-pillar, C-pillar and the top of the tailgate of a SUV. The geometric features of these cavities are extracted and represented using three equivalent regular cavity models. The experimental studies on the sound phenomena and formation mechanism of these cavities were carried out in a small acoustic wind tunnel. The results indicate that the three cavities exhibit two different sound phenomena, i.e. strong resonance and weak resonance. Further numerical simulations are performed to analyze the acoustic characteristics of the cavities. The results show that self-excited oscillations are difficult to form in the small opening cavities, such as those near the B-pillar and C-pillar. Instead, pulsating excitation at the opening induces weak resonance in the cavity mode. In contrast, the cavities with wider openings near the tailgate can form self-excited oscillations, which resonate with cavity acoustic modes or Helmholtz resonance modes to produce strong resonance with whistling noise. The differences in phenomena and mechanisms between automobile door sealed cavities and large cavities are revealed. A method for determining the frequency of self-excited oscillations is proposed by characterizing the vortex motion in the Q-factor cloud diagram. Additionally, the contribution of self-excited oscillations to the peak values in the cavity sound pressure spectrum is clearly explained, while effectively defining their frequency.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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