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1.
This paper presents a KIVA-3 code based numerical model for three-dimensional transient intake flow in the intake port-valve-cylinder
system of internal combustion engine using body-fitted technique, which can be used in numerical study on internal combustion
engine with vertical and inclined valves, and has higher calculation precision. A numerical simulation (on the intake process
of a two-valve engine with a semi-sphere combustion chamber and a radial intake port) is provided for analysis of the velocity
field and pressure field of different plane at different crank angles. The results revealed the formation of the tumble motion,
the evolution of flow field parameters and the variation of tumble ratios as important information for the design of engine
intake system. 相似文献
2.
INTRODUCTIONTheinternalcombustionengineisthemostwidelyusedpowermachineryinmodernsociety ,butisalsooneofthebiggestenvironmentalpol lutantsources.Tomeetmoreandmorestringentemissionrequirements,manyadvancedtech niques,suchastheleanburntechnique ,multi valvet… 相似文献
3.
Thelevel of vibration and noiseis animportant estima-tionindexoninternal combustionengines .As vibrationandnoise legislations are continually introduced and progres-sivelyrestricted,lowerlevel noise becomesincreasinglyim-portant .The traditional design pe… 相似文献
4.
Effects of exhaust gas recirculation （ EGR） on homogeneous charge combustion of n-heptane was studied through simulation and experiment. Experiments were carried out in a single cylinder, four-stroke, air cooled engine and a single cylinder, two-stroke, water cooled engine. In the four-stroke engine, experiments of the effects of EGR were examined using heated N2 addition as a surrogate for external EGR and modifying engine to increase internal EGR. The ignition timing was sensitive to EGR due to thermal and chemical effects. EGR or extra air is a key factor in eliminating knock during mid-load conditions. For higher load operation the only way to avoid knock is to control reaction timing through the use of spark ignition. Experimental and modeling results from the twostroke engine show that auto-ignition can be avoided by increasing the engine speed. The twostroke engine experiments indicate that high levels of internal EGR can enable spark ignition at lean conditions. At higher load conditions, increasing the engine speed is an effective method to control transition from homogeneous charge compression ignition （ HCCI） operation to non-HCCI operation and successful spark ignition of a highly dilute mixture can avoid serious knock. 相似文献
5.
高利军 《邢台职业技术学院学报》2006,23(1):67-69
针对输液管道振动大,噪声污染严重的问题,本文结合振动理论、声场理论、应用有限元以及边界元方法对输液管道受激振动的噪声辐射过程进行研究,并提出了一种新的低噪声管道结构设计方法。 相似文献
6.
用不同方法进行发动机噪声源识别的研究 总被引：9，自引：0，他引：9
发动机噪声源识别对于制定发动机降噪措施十分重要 ,而像油底壳、气门罩、前齿轮室盖等罩壳类零件通常是发动机的主要噪声源 .本文用铅覆盖法和表面振动测量法对一台六缸工程机械用柴油机进行了表面噪声源识别的研究 ,得到了罩壳类零件按噪声能量大小的排列顺序 ,文中首先在半消声条件下利用铅覆盖技术测量了这些罩壳类零件的声功率 ,然后又研究了它们的振动特性 ,并通过表面振动速度的面积时间均方值预测了其声功率 .两种方法的测量结果吻合较好 ,说明了它们在工程领域应用的有效性 相似文献
7.
Study of engine noise based on independent component analysis 总被引：1，自引：0，他引：1
HAO Zhi-yong JIN Yan YANG Chen 《浙江大学学报(A卷英文版)》2007,8(5):772-777
Independent component analysis was applied to analyze the acoustic signals from diesel engine. First the basic prin-ciple of independent component analysis (ICA) was reviewed. Diesel engine acoustic signal was decomposed into several inde-pendent components (ICs); Fourier transform and continuous wavelet transform (CWT) were applied to analyze the independent components. Different noise sources of the diesel engine were separated, based on the characteristics of different component in time-frequency domain. 相似文献
8.
A multi-dimensional computational fluid dynamics (CFD) approach was proposed in this study aiming to calculate the transfer matrix of an engine exhaust muffler in the conditions with and without mean flow. The CFD model of the muffler with absorptive material defined as porous zone was calibrated with the measured noise reduction without mean flow, and was further employed to study the effect of the mean flow on the acoustic performance of the muffler. Furthermore, the exhaust acoustical source was derived from the calculated transfer matrices of six different additional acoustic loads obtained by the proposed CFD approach as well as the measured tail noise based on a multiload least squares method. Finally, the exhaust noise was predicted based on Thevenin??s theorem. The proposed CFD approach was suggested to be able to predict the acoustic performance of a complex muffler considering mean flow (without and with mean flow) and heat transfer, and provide reasonable results of the exhaust noise. 相似文献
9.
发动机涡轮增压器是一种轻型高速旋转机械,其作用是通过增压增加气缸进气量,提高发动机的燃油经济性和动力性．发动机涡轮增压器核心部件是双盘双支撑的转子轴承系统,所以对转子轴承系统运动稳定性的研究显得尤为重要．通过传递矩阵法建立求解涡轮增压器转子系统临界转速的计算模型,将某型国产汽油机涡轮增压器转子系统的参数带入数学计算模型．利用Matlab软件编程计算涡轮增压器转子系统的临界转速,并通过台架试验验证了理论计算的正确性,为涡轮增压器转子系统设计提供理论参考． 相似文献
10.
A novel sound quality simulation approach was proposed to optimize the acoustic performance of a four-cylinder diesel engine. Finite element analysis, single-input and multiple-output technology, flexible multi-body dynamics, and boundary element codes were used to acquire the hexahedron-element model, experimental modal frequencies, vibration velocities, and structurally radiated noise of the block, respectively. The simulated modal frequencies and vibration velocities agreed well with the experimental data, which validated the finite-element block. The acoustic response showed that considerable acoustic power levels existed in 1500–1900 Hz and 2300–2800 Hz as the main frequency ranges to optimize the block acoustics. Then, the optimal block is determined in accordance with the novel approach, which reduces the overall value, high-frequency amplitudes, and peak values of acoustic power; thus, the loudness, sharpness, and roughness decline to make the sound quieter, lower-pitched, and smoother, respectively. Finally, the optimal block was cast and bench-tested. The results reveal that the sound quality of the optimal-block engine is substantially improved as numerically expected, which verifies the effectiveness of the research approach. 相似文献
11.
Influence of input acoustic power on regenerator＇s performance 总被引：2，自引：0，他引：2
TANG Ke HUANG Zhong-jie JIN Tao BAO Rui CHEN Guo-bang 《浙江大学学报(A卷英文版)》2007,8(9):1452-1456
Performance of a pulse tube cooler significantly depends on the efficient operation ofits regenerator. Influence of input acoustic power on regenerator＇s performance is simulated and analyzed with simple harmonic analysis method. Given regenerator＇s dimensions and pressure ratio, there is an optimal input acoustic power for achieving a highest coefficient of performance, due to a compromise between relative time-averaged total energy flux in regenerator and relative acoustic power at regenerator＇s cold end. Additionally, optimal dimensions of regenerator are also estimated and presented for different input acoustic powers. The computed optimal diameter obviously increases with increase of input acoustic power, while the optimal length decreases slightly, and as a result, a larger input acoustic power requires a smaller aspect ratio （length over diameter）. 相似文献
12.
动车风源系统专门用于为动车整车制动系统供风,而漏风问题会影响供风效率乃至整个制动系统。旨在利用声发射传感器技术,针对风源系统中最常见的漏风问题进行检测,并利用时延估计技术进行泄漏点定位,从而及时发现泄漏点并采取措施解决问题,以降低风源系统发生故障的风险,减少故障带来的损失。采用小波包分析对传感器采集的数据进行分解重构,以减小外界环境噪音对结果的干扰,最后利用互相关分析及定位公式对漏风点进行定位。仿真实验结果表明,该方法具有较强的抗干扰能力与较高的精度,精度可达到95%左右,因此能较好地解决风源系统漏风定位问题。 相似文献
13.
Bülent 《浙江大学学报(A卷英文版)》2010,11(2):106-114
In this study, an electro-mechanical valve （EMV） system for the intake valve ofa fottr stroke, single cylinder, overhead valve and spark ignition （SI） engine was designed and constructed. An engine with the EMV system and a standard engine were tested to observe the effects of the EMV on engine performance and emissions at different speeds under full load. The EMV engine showed improved engine power, engine torque and break specific fuel consumption （BSFC）. A 66% decrease in CO emissions was also obtained with the EMV system, but hydrocarbons （HC） and NOx emissions increased by 12% and 13% respectively. 相似文献
14.
某系列空调器室外机测试时发现低频噪声,通过连接管或墙壁传到室内侧。分析和实验证明,这是由压缩机噪声和室外风扇噪声叠加而成的。通过系统优化设计,室外侧100Hz的噪声峰值降低了8dB（A）。 相似文献
15.
设计了一种应用于传统非可变配气正时的发动机进气系统的固定式单向阀.将该阀安装于发动机气缸体与化油器之间,在中低转速下可阻止已进入发动机气缸内的混合气发生倒流现象,从而能有效地降低传统发动机的燃油消耗率.介绍了单向阀簧片的3种运动形式和对应的影响因素,分析了簧片的设计要求,重点研究了簧片的运动规律,建立了所设计的单向阀簧片的运动微分方程式,并运用Matlab编程求解出簧片的理论固有频率,为单向阀的簧片的形状和限位板高度等的设计提供参考和依据. 相似文献
16.
运用流体动力学模拟软件对某发动机实验室三维数值模型进行数值模拟,结合模拟结果分析其内部温度场、速度场变化。对比有送风与无送风2种情况计算结果,比较发动机实验室空调系统的温度、速度分布以及变化规律;分析空气流动,讨论合理的气流组织方式。结果表明,设计合理的空调系统可以使实验室内部温度降低50 K,同时对实验室设计中出现的热堆积问题提出解决建议。 相似文献
17.
阐述了消声器降低空调器压力脉动噪音的机理,给出了空调膨胀式消声器的最佳设计方法。通过理论计算与实验研究,详细讨论了如何在空调器中应用膨胀式消声器消除制冷系统的压力脉动噪音。 相似文献
18.
王会 《北京工业职业技术学院学报》2006,5(1):40-42,56
常规的增压器存在与发动机协调性差、压力不可调、发动机有效运行区间窄、低速扭矩小及加速性能差等问题,与车用发动机要求有较高的扭矩储备和加速性能大不相符.为了改善增压发动机的低速扭矩特性和动态响应特性采用可变几何截面增压系统,根据发动机运行状况,调节增压器的有效流通面积,使其低速时以小流量运行高速时以大流量运行. 相似文献
19.
环保设备是环境工程专业的一门重要的专业课,它建立在水污染控制工程、大气污染控制工程、噪声控制工程等课程知识的基础上,培养环境工程专业学生掌握环保设备的原理和设计、选型的基本理论和方法。在教学中发现,学生对本课程中的一些细节问题掌握不够扎实,在环保设备设计原理及应用方面,掌握的知识薄弱。所以,建议改革教学形式,达到更好的教学效果。 相似文献
20.
邱兴阳 《宁德师专学报(自然科学版)》2012,24(3):282-285
变频技术是变频空调的核心技术,它不仅能降低噪声,还能提高制冷/热效果和舒适度.而使其拥有较高的可靠性和较低的功耗是由于在变频技术中采用了模块化的功率器件IPM智能功率模块.IPM不但能减少工作噪声,还可以提高系统的可靠性及控制效率.新一代的IPM还改进内部的寄生结构,在低正向压降、高开关速度和宽安全工作区方面进行优化设计,因此在空调和其它的家用电器中得到更广泛的应用. 相似文献