车用涡轮增压器空气压缩机流场的数值模拟研究

发布时间：2018-06-26 19:34

本文选题：离心压气机 + 内流特性　；参考：《重庆理工大学》2016年硕士论文

【摘要】：随着时代的变迁与进步,废气涡轮增压技术逐渐被重视并被广泛应用于各类车辆动力系统中,以实现发动机的高功率、大扭矩和低排放目标。而离心压气机作为涡轮增压系统的重要组成部件,其流动性能的优劣成为涡轮增压技术的关键。因此,设计出兼具高压、高效、低噪和体积小等优点的离心压气机是当务之急。离心压气机主要由进气道、旋转叶轮、扩压器、蜗壳等部件组成,简单的机构使得每一个部件结构的变动都会对压气机的性能产生至关重要的影响。但是,随着研究的深入,越来越多的学者认为,各部件之间相互耦合作用对压气机性能产生的影响也是不能忽略的。本研究基于此点出发,对压气机进行了数值模拟研究,并对未来压气机的研发提供一定的借鉴意义。本文以某型号的涡轮增压器离心压缩机为研究原型,首先考虑了扩压器与蜗壳的耦合作用对压气机性能的影响,从扩压器出口相对于蜗壳位置的角度入手,建立两种压气机模型,对这两种压气机的流场和声场进行全流道数值模拟,并对内流特性进行对比分析。结果显示,转速越高,出口静压值越大,压比越大;在同一转速工况下,小流量时,非内嵌式压气机的整体性能要高于内嵌式,随着流量的增加,内嵌式的整体性能逐步提高,在大流量时其性能则要高于非内嵌式;压气机噪声都表现为随着转速的增加而增大,随着流量由小增大而先减小后增加;在设计工况下,非内嵌式扩压器与蜗壳组合方式下的性能要优于内嵌式,整机表面最大声功率比内嵌式压气机低4.936dB。同时考虑到转子部分对压气机性能影响较大,遂参考转子叶片的设计参数,通过改变转子叶片出口角度,对具有不同叶片出口角的压气机进行全流道数值模拟,分析了叶片的不同出口角对压气机内流特性的影响。结果显示,较大的叶片出口角虽会增加压气机的工作范围,但是过大的出口角却对提高压比和效率不利,即压气机的压比和效率会随着叶片出口角的逐渐增大而减小;对噪声而言,整机声功率则表现为随着出口角度的增大而先减小后增大,即存在合适的出口角使压气机在设计工况下的整体噪声相对较小。
[Abstract]:With the change and progress of the times, exhaust gas turbocharging technology has been paid more and more attention and widely used in various vehicle power systems to achieve high power, high torque and low emission targets. As an important component of turbocharging system, the flow performance of centrifugal compressor becomes the key of turbocharging technology. Therefore, it is urgent to design a centrifugal compressor with the advantages of high pressure, high efficiency, low noise and small volume. Centrifugal compressor is mainly composed of inlet, rotating impeller, diffuser, volute and so on. However, with the development of the research, more and more scholars think that the influence of the coupling between the components on the compressor performance can not be ignored. Based on this point, the numerical simulation of the compressor is carried out, and it provides some reference for the future research and development of the compressor. In this paper, a certain type of turbocharger centrifugal compressor is used as the research prototype. Firstly, the effect of the coupling of diffuser and volute on compressor performance is considered, starting from the angle of diffuser outlet relative to volute position. Two compressor models were established to simulate the flow field and sound field of the two compressors, and the characteristics of the inner flow were compared and analyzed. The results show that the higher the rotating speed, the greater the static pressure value of the outlet and the greater the pressure ratio. Under the same rotating speed condition, the overall performance of the non-embedded compressor is higher than that of the embedded compressor, and with the increase of the flow rate, the integral performance of the embedded compressor is gradually improved. At large flow rate, the performance of compressor is higher than that of non-embedded type. The noise of compressor increases with the increase of speed, decreases first with the increase of flow rate, and then increases with the increase of flow rate. The performance of non-embedded diffuser and volute is better than that of embedded compressor, and the maximum sound power of the whole machine is 4.936 dB lower than that of the embedded compressor. At the same time, considering that the rotor part has great influence on the compressor performance, referring to the design parameters of the rotor blade, the full channel numerical simulation of the compressor with different blade outlet angles is carried out by changing the rotor blade outlet angle. The influence of different outlet angles of blades on the flow characteristics of compressor was analyzed. The results show that the larger blade outlet angle will increase the working range of compressor, but the excessive outlet angle will be unfavorable to the increase of pressure ratio and efficiency, that is, the pressure ratio and efficiency of compressor will decrease with the increase of blade outlet angle. As far as noise is concerned, the sound power of the whole machine decreases first and then increases with the increase of the outlet angle, that is, the overall noise of the compressor is relatively small under the design condition because of the existence of proper outlet angle.
【学位授予单位】：重庆理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U464.135.2

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