共查询到20条相似文献,搜索用时 18 毫秒
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《JSAE Review》1994,15(4):323-327
Conventionally, sound insulation materials have been applied to control interior noise above 500 Hz, and damping materials to control interior noise below 500 Hz. In this paper, the acoustical materials for vehicle panels, which consists of damping materials and sound insulation materials, are investigated by using a two-degrees-of-freedom system.The investigation shows that sound insulation materials can become effective to reducing interior noise below 500 Hz byducin their stiffness. This stiffness depends on not only the spring of the material itself but also on the pneumatic spring which is determined by air-flow resistance.This paper concludes with applications of techniquws to reduce interior noise below 500 Hz by improving sound insulation materials. 相似文献
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《JSAE Review》1999,20(2):211-216
Impact force caused by piston slap is one of the major mechanical noise sources in a diesel engine. The optimization of piston pin offset for impact force reduction has been reported by many researchers. However, if a modification has large effect at idling, high-speed noise tends to increase and vice versa. It was very difficult to reduce piston slap noise at all engine speeds. In this paper, the mechanism of the piston slap was investigated precisely utilizing numerical simulation. Simultaneous noise reduction in the conditions of both idling and high speed was achieved successfully by optimizing the piston's center of gravity as well as piston pin offset. Furthermore, engine sound quality was also significantly improved. 相似文献
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利用倒拖法对某车用涡轮增压缸内直喷汽油机空载加速和半载加速工况进行了燃烧噪声试验研究。联合发动机缸内燃气压力测试结果,通过分析气体动力载荷对其燃烧噪声的影响,进一步探讨燃烧噪声产生的根本原因。试验结果表明,在中低转速时,燃烧噪声随着发动机负荷的增加而增加,同时燃烧噪声对整机总声功率的贡献值也在随之增加。在较高转速时,燃烧噪声对整机总声功率的贡献值随着发动机负荷的增加变化不显著。就半载加速和空载加速工况时燃烧噪声的平均贡献值来看,空载加速时燃烧噪声对整机噪声的平均贡献值为22.2%,明显小于半载加速时的43.6%。随着发动机转速的提高,最大气缸压力及最大压力升高率总体变化趋势和燃烧噪声变化趋势一致,同时加速时最大气缸压力变化对燃烧噪声的影响更明显。 相似文献
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轻型载货汽车车外噪声分析与控制 总被引:1,自引:0,他引:1
用声强扫描法对国产某轻型载货汽车车外噪声源进行了识别,确定了其车外主要噪声源。开发了材料声学特性测量系统,并对多种车用吸声、隔声材料进行了测试与分析。根据被试轻型载货汽车车外主要噪声源的特性合理地选择吸声、隔声材料和噪声控制方案,对其进行了降噪处理。通过对降噪前、后该车车外噪声进行测试分析表明,采取降噪措施后,被试车辆车外动态加速噪声由84dB(A)下降到78dB(A),能够满足国家标准GB1495—2002对该类车辆车外动态加速噪声限值的要求。 相似文献
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车载装备(如柴油发电车)的低噪声设计主要是针对装备工作时的噪声组成、特点,结合噪声的控制方式和阻性、抗性消声原理把噪声控制在声场内,限制其传播,采取减震、隔声和消声等措施,使其强度和能量衰减,从而达到低噪声工作的目的. 相似文献
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在对某款摩托车发动机噪声源识别试验中,通过声强测量发现,曲轴箱体的表面辐射噪声是主要噪声源,但却不能确定该噪声源的成因。在综合应用了共振频率分析、分别运行法和频谱分析法等噪声源识别方法后,最终发现该噪声源来自发动机的正时链轮和链条的冲击噪声,并发现其位置与声强等高线指示的声源位置并不一致。 相似文献
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采用浸入边界-格子玻尔兹曼法建立密封系统流固耦合模型,研究不同预压缩量下的密封条隔声。利用浸入边界法建立密封条的力学模型,同时用格子玻尔兹曼法模拟周围流体,两者结合完成实际车门密封条系统的二维简化计算模型。通过比较动态载荷下有限元和浸入边界模型的模拟结果,验证了系统建模的有效性。设计并搭建密封条隔声试验台架,可测量不同预压缩条件下的隔声。试验与仿真的结果相互验证,结果显示,有效挤压下密封条隔声量随着预压缩量缓慢上升,而产生缝隙后隔声量将显著下降。研究证明浸入边界-格子玻尔兹曼法处理流固耦合建模简便且计算效率高,在汽车密封系统相关的失效、隔声、泄漏噪声等问题上有广泛的应用前景。 相似文献
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