提速及高速列车轮轨噪声的理论计算和分析

According to the basic relations of wheel/rail interaction with spectrum analysis method and considering the area of contact between the wheel and rail,the wheel/rail coupled vibrations excited by the small-scale roughness of the running surfaces of the wheel and rail are studied.The formulas of the space-averaged spectra of vertical and lateral vibration level of the wheel and rail are presented.Not only the vertical impedance and lateral impedance of steel rails,but also the radial impedance and axial impedance of wheels are successfully deduced.In the analysis of the steel rails′ vertical impedance,considering the sleepers′ quality and using the model of double-layer continuous resilience foundation beams,the rails are divided into Euler Beams and Timoshenko Beams.In the analysis of the steel rails′ lateral impedance,the rails are regarded as double structure.The rail heads are considered as Timoshenko girders considering shearing force and rotation and the webs are considered as spring and damp associating heads and foots.In the analysis of the wheel impedance,the wheel is simplified as an elastic circle loop,which taking the rigidity of web plate into consideration.The tread is regarded as an elastic loop,and the web plate is regarded as a spring component connecting wheel tread and wheel axle.Based on the wheel/rail coupled vibration research,considering the effects of the ground reflection the prediction expressions for the sound pressure level spectrum of the wheel/rail rolling-noise are given by means of the application of the structural sound radiation theory.In order to demonstrate the accuracy of this expression,the calculation results of wheel/rail high-frequency response and wheel/rail noise are compared with the test results in authorized reference.And the wheel/rail rolling-noise from existed railways in our country are predicted and measured.The numerical results and the measured ones agree well.With this existing model of wheel/rail rolling noise,the wheel/rail noise frequency,distance and speed characteristics are simulated and analyzed in this thesis.It shows that the wheel/rail noise spectrum distributes in a wide frequency range between 200～4 000 Hz,among which wheel vibration noise dominates between the 500～1 700 Hz frequency bands.Below 500 Hz or above 1 700 Hz frequency bands,wheels noise is the primary source.Among the total rail vibration noise,the rail vertical vibration noise takes the leading stand below 2 200 Hz frequency bands,while above 2 200 Hz frequency bands the dominant noise sources are rail′s vertical and lateral vibrations.Otherwise among the total noise of wheel,the dominant noise source is wheel axial vibration below 1 800 Hz frequency range,and the wheel radiant vibration is chief above 1 800 Hz.The effects on wheel/rail rolling noise are quantitatively studied with this model changed in the parameters which include roughness magnitude,wheel and rail parameters.Conclusions are drawn as follows: the roughness magnitude increasing expedites wheel/rail rolling-noise to rise radically within the frequency range of 200～4 000 Hz.It is beneficial for the reduction of wheel/rail rolling-noise to decrease the wheel radius,increase the thickness of wheel web,mass of wheel tread and rigidity of padding plate blank properly.

疏水进入除氧器水箱喷注噪声的实验研究

通过实验探索了蒸汽在水下有限空间喷注时喷注噪声的辐射规律，发现其Ａ声压级同水的过冷度有直接关系；喷头孔径对最大喷注噪声Ａ声压级的影响不大，但较大的孔径可以使最大Ａ声压级出现的位置向低温处移动，而较小的孔间距可降低喷注噪声。同时发现，蒸汽水下喷注噪声的产生机理和空气动力性噪声的产生机理是不完全相同的，因此对小孔喷注噪声的研究结果不能直接应用于蒸汽水下喷注噪声的预测。

舰船通风系统噪声分析与控制研究

本文结合舰船的实际情况,通过对舰船通风系统噪声的产生、传播途径及影响因素的分析,从被动噪声控制技术的角度,提出控制通风系统噪声的设计方法和技术措施,以达到改善舰员的生活环境条件和提高舰船隐身性能的目的。

丙烯腈吸收塔放空管道噪声控制

某石油化工总厂丙烯腈车间的吸收塔在放空负荷增大以后产生了较严重的噪声,对生产环境造成极大污染。为对丙烯腈吸收塔的放空管道实施噪声控制,改善工厂以及周边厂家的生产环境,进行了噪声控制方案设计及消声器设计。项目实施后,噪声绝对值降低了20分贝,噪声幅度降低达24％。

梁系统计能量分析中传输波的影响（英文）

机械系统中激励源传出的波将沿传输路径衰减,并会经由含源子系统边界传递出去,因而只有输入功率的残余部分以混响场的形式消耗在该子系统内。为提高应用统计能量分析法(SEA)计算振动噪声的精度,对上述过程进行深入分析,并以一个简单梁系为例,给出传入该梁系的输入功率的表达式。分析结果表明,传输波对计算结果的影响随着损耗因子的增加而增加。同时,分析将传输波的影响计入诸如舰船这种复杂空间结构的实际可行性。估算结果表明,仅对含源子结构考虑传输波的影响是充分可行的。