共查询到20条相似文献,搜索用时 203 毫秒
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采用自编的CFD程序数值研究了无叶扩压器对离心压缩机流场及气动性能的影响.采用当地时间步长、多重网格以及隐式参差光顺等技术来加速收敛,以质量流量来代替出口静压的出口边界条件,使出口静压在计算过程中与给定的流量工况自动匹配,大大节省了计算时间.对Krain叶轮后带等面积与直壁两种形式的无叶扩压器离心压缩机内部流场进行了计算与分析,结果表明:直壁型无叶扩压器离心压缩机的效率低于等面积无叶扩压器离心压缩机的效率;直壁型无叶扩压器使得叶轮出口的流动出现分离;扩压器的形式对离心叶轮的整体气动性能影响并不大;在进行离心叶轮数值研究时,叶轮后的延伸区最好采用等面积无叶扩压器,以尽量减小无叶扩压器所引起的计算误差. 相似文献
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基于RNG k-ε湍流模型对斜流泵内部三维流场进行了数值计算,重点针对非设计工况下的斜流泵叶轮进出口环量分布特征进行了分析。研究结果显示,在设计点附近的叶轮进口环量受叶片进口边影响较大,不同采样线的环量分布具有一定差异,小流量工况下受到叶轮进口回流的影响,不同采样线的环量分布趋于一致。叶轮出口环量分布受采样线位置影响较小,在设计流量点时,叶轮出口呈等环量分布。在小流量工况点,受到叶轮出口回流的影响,叶轮出口外缘处的环量数值显著增大。通过研究还发现,从叶轮出口流道通过轮毂一侧回流进入叶轮的流体微团具有与叶轮旋转方向相反的圆周速度分量,其环量数值甚至低于同工况下的叶轮进口环量值。 相似文献
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前言高压离心压缩机的最后几级,由于容积流量的缩小,叶轮的相对宽度很小,宽度的绝对尺寸往往只有几毫米。这时,边界层对气流的流动和损失有着极大的影响,级效率不高。叶轮内的流动损失主要是流动摩擦损失和法向压差引起的二次流损失,这两者又相互影响。由于二次流的存在使边界层的流动具有三元性 相似文献
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Lei Deng Wenlei Dai Xinyun Wang Junsong Jin Jianjun Li 《The International Journal of Advanced Manufacturing Technology》2018,97(5-8):1663-1672
In the forming process of rib-web parts, which are widely used in automobiles and aircrafts, severe streamline disorder often occurs because of unreasonable metal flow. In this study, a back-pressure-controlled forming method that can control the direction of metal flow was introduced. The effects of key parameters on metal flow were investigated, including the back-pressure value, loading mode, and back-pressure distance. The results showed that streamline defects can be avoided and the final forming load can be reduced by reasonably controlling the back-pressure parameters. The constant back-pressure mode was more conducive to achieving good forming quality compared with the linear-increased back-pressure mode. From the stress analysis of metal flow, it was demonstrated that the stress state in the rib root is changed by the back pressure, which makes the metal flow more easily along either the tangential or the radial direction. The advantages of the back-pressure-controlled forming method were confirmed by applying it to a compressor scroll rotor. 相似文献
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Kyoung-Ku Ha Tae-Bin Jeong Shin-Hyoung Kang Hyoung-Jin Kim Kwang-Min Won Chi-Yong Park Woo-Youl Jung Kyung-Seok Cho 《Journal of Mechanical Science and Technology》2013,27(11):3287-3297
A variety of centrifugal compressors are used in various fields of industry such as aircraft, home appliances, and vehicles. Comfort and quietness are important in these uses. As a result, noise has become an important consideration in compressor design besides the conventional performance parameters such as efficiency and pressure ratio. However, compressor noise has been difficult to understand because of the lack of information. The aim of this paper is to investigate the aero-acoustic characteristics of a centrifugal compressor for the fuelcell vehicle by experiments. The existing compressor system is modified to measure the internal pressure fluctuation at the impeller inlet, the impeller outlet and the diffuser outlet. Four microphone probes are also installed to determine the external noise levels and spectra of the compressor in an airtight room according to the RPM and mass flow rate. The test results show the possibility to tell the relative noise level of a centrifugal compressor with the internal pressure data. The external microphone signals have relation to the internal pressure signals. They have similar patterns and spectra. It is a noteworthy phenomenon because it is easier and inexpensive to predict pressure behaviors than noise characteristics of centrifugal compressors. The dominant noise source is the tonal noise during normal operation. But the broadband noise component due to the turbulent flow in the compressor increases during low flow rate operation. Computational simulations are carried out to describe these phenomena and to identify noise indicators. The turbulence kinetic energy and the pressure distribution obtained from CFD results may be indicative of the relative noise intensity of the compressor. The experimental facility, instrumentation and simulation conditions are described, and the results are presented in this paper. 相似文献
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用数值模拟方法对高压比大小叶片斜流式叶轮内部全三维有粘流场进行了详细分析,获得该压缩机的特性曲线和主要参数分布。计算结果表明,设计点达到设计要求值,斜流叶轮内部流动正常,满足性能要求,叶轮的小叶片在气流通道后部还有一定的改进余地。 相似文献
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Research on the cathode design and experiments of electrochemical machining a closed impeller internal flow channel 总被引:2,自引:0,他引:2
L. Tang Q. L. Zhu J. S. Zhao Z. J. Fan 《The International Journal of Advanced Manufacturing Technology》2017,88(9-12):2517-2525
In order to improve the electrochemical machining (ECM) precision and efficiency of a closed impeller internal flow channel, the internal flow channel cathode shape and structure were optimized by gap flow field simulation. Firstly, the theoretical model and three-dimensional gap flow field simulation geometric model were set up. Next, the inter-electrode gap flow field simulation results were draw from the streamline, velocity, and pressure cloud picture. Secondly, the cathode and the frock clamp were designed according to the simulation results. Finally, the verification experiment was carried out to evaluate the cathode structure and the ECM process parameters, and the experimental results were consistent with the simulation results. The whole process is stable and no short-circuit phenomenon with the forward flow field machining pattern. The results show that the method of gap flow field simulation-assisted ECM cathode design is useful and economical for machining closed impeller internal flow channel. 相似文献