共查询到18条相似文献,搜索用时 187 毫秒
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《内燃机工程》2014,(1)
通过两种转速(120 000r/min和140 000r/min)下压气机性能试验与仿真结果对比分析得知其总体误差范围在5%左右,验证了ANSYS CFX软件在压气机性能模拟计算的可靠性;采用数值计算方法分别对具有圆形和椭圆形前缘的压气机叶轮与涡壳的组合性能进行计算,得到了相关转速下压气机特性曲线,分析了四种不同长短径之比(a/b=1、3、5、8)前缘的叶轮流道内的气体流动特性。研究结果表明:压气机特性随着前缘长短径比值的增大呈先增后减的趋势,最高压比LE5比LE1提高了5%,最大效率LE3比LE1提高了6.7%,且流量范围也有所增加;在一定范围内增大前缘长短径比可以抑制前缘分离流动,改善叶轮出口处流场。 相似文献
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为了提升低转速工况下压气机的气动性能,采用人工神经网络与遗传算法相结合的优化方法对某单级离心压气机离心叶轮的弯特性进行优化计算。利用NUMECA软件对该离心压气机进行了不同转速的数值模拟,得到压气机不同工况下的气动性能。通过设置不同控制参数和曲线形式对离心叶轮叶片进行参数化拟合,以8个改变叶片弯特性的参数为自由参数进行了叶型优化设计,最终得到了优化后的叶轮叶片。结果表明:优化后在低转速的设计工况下离心压气机压比增加了4.69%,稳定裕度拓宽了17.41%。 相似文献
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基于二级可调增压柴油机高海拔性能试验,采用计算流体力学(CFD)和柴油机工作过程计算方法,开展高海拔条件下压气机叶轮结构优化及其对柴油机性能影响的研究.研究结果表明:海拔5 500 m,压气机叶轮主叶片及分流叶片前缘前掠6.27°、分流叶片向主叶片压力面偏折12.09°,压气机叶轮流道内流动损失明显降低,出口处流动稳定性提高,压比、效率及流量范围分别提高4.16%、2.63%及6.58%;压气机叶轮优化后,二级可调增压柴油机中低转速燃烧过程得到明显改善,滞燃期和燃烧持续期缩短;柴油机1 200 r/min全负荷工况最高燃烧压力升高9.53%,累计放热量提高8.78%,转矩提高5.82%,燃油消耗率降低4.42%. 相似文献
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压气机叶轮内部流动的基本理论研究指出:a)解决压气机内部非粘性流动问题能获得防止喘振的必要(但不是充分的)准则;b)采用后倾叶片不是唯一可以增加压气机有用流量范围的叶片通道改进措施;c)能获得一个比原来想象宽得多的有用流量范围。本研究建议的一种可供选取的方法已在3. 0以上的压比下进行了试验。这种新方法在能使叶轮的设计转速下的喘振流量减少百分之五十时导风轮几何尺寸与作为比较标准的常规径向叶片叶轮的导风轮尺寸保持一致。这种方法提供了预测径流涡轮机械的喘振流动特性的可能性。反之,也可以由预先给定叶片几何尺寸来设计能满足预先规定的喘振堵塞流量比的元件。看来在不牺牲元件最大效率的情况下,离心压气机的有用流动范围能扩大到堵塞流动能力的15~20%。 相似文献
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《热能动力工程》2016,31(4)
采用全三维气动设计技术,设计了4种具有掠角叶片和带翼型叶片扩压器的涡轮增压跨音速离心压气机,并采用数值模拟手段研究了叶片前缘不同后掠角对压气机内部工质流动的影响。研究结果表明:主叶片前缘不同后掠角会使压气机堵塞流量(堵塞工况下的工质流量)增加,提高压气机流通能力,同时,可以有效改善通道内低能流团的分布;但由于主叶片轴向弦长缩短,会造成喘振裕度的减少,以及主叶片前缘脱体激波角增大和槽道激波的增强;对截面二次流分析结果表明:叶片前缘的后掠角对二次流的影响主要表现在叶轮进口附近,对出口影响不大。对比不同前缘后掠角压气机内部流动情况发现,掠角越小,叶片叶顶负荷越小,叶片表面压差也越小,流动越稳定;掠角越大,虽然叶轮通道上游产生的激波越强烈,但是可以明显改善通道下游气流流动情况。 相似文献
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基于试验测试数据建立增压柴油机的仿真模型,开展0~4 000m高原适应性研究工作,研究增压柴油机性能及压气机性能海拔变化关系,并研究不同海拔下压气机内部流动状况,分析压气机效率下降原因。研究结果表明:高海拔工况下,柴油机功率、转矩与燃油消耗率下降,进气流量减少,增压压力下降,压气机压比增大,效率下降。压气机子午面的相对总压的低压区域压力较小,叶顶间隙间及叶轮出口高熵值区域增大且范围提前。跨音速流动区域增大,激波损失增大,叶顶间隙流加强,泄漏损失增大,分流叶片压力侧主流与低速泄漏流掺混,尾迹区域增大,掺混损失增加,压气机叶轮内部损失增大。因此高原环境下,压气机效率降低。 相似文献
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介绍了一个带有分流叶片的小流量离心压气机的设计过程。这个叶轮的主要设计参数为流量0.215kg/s,转速95000r/min,压比1.8。简要介绍了离心压气机设计系统,其中包括初步设计及优化模块,性能仿真模块,叶轮造型模块。使用三维NS方程对所设计的离心压气机在设计点的性能进行了计算,计算结果表明所设计的离心压气机基本能够满足设计要求。 相似文献
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Through means of 3-D CFD (Computational Fluid Dynamics) method, a novel axial compressor with different impeller shapes compressing water vapor as refrigerant was investigated. The numerical simulation focuses on the fluid flow from compressor impeller inlet to outlet. The overall performance level and range are predicted. Different blade patterns with different hub sizes were compared regarding the aerodynamic performance. Independent of the blade pattern, in this numerical investigation the largest hub diameter shows the highest pressure ratio and efficiency at narrowest operating range. 相似文献
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Yuxing Bai Fanyu Kong Sunsheng Yang Kai Chen Tao Dai 《International Journal of Hydrogen Energy》2017,42(29):18709-18717
Hydraulic turbine is used for recovering power by using reverse running pump. In order to improve the efficiency of turbine working condition, the impeller with forward-curved blades was applied instead of the impeller with backward-curved blades. The effects on the performance of hydraulic turbine and inner flow character with different blade wrap angles were studied by the method of numerical simulation. The results show that: with the blade wrap angle growth, the maximum efficiency increases, but the range of the flow rate at the high efficiency decreases rapidly; the flow state of hydraulic turbine which in small flow area obtains a remarkable improvement; the flow within the impeller improves and the friction loss increases; the hydraulic loss in the small flow area inside the impeller declines but it grows in the large flow area. 相似文献
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In order to analyze the influence of blade outlet angle on inner flow field and performance of low-specific-speed centrifugal pump, the flow field in the pump with different blade outlet angles 32.5° and 39° was numerically calculated. The external performance experiment was also carried out on the pump. Based on SIMPLEC algorithm, time-average N-S equation and the rectified k-? turbulent model were adopted during the process of computation. The distributions of velocity and pressure in pumps with different blade outlet angles were obtained by calculation. The numerical results show that backflow areas exist in the two impellers, while the inner flow has a little improvement in the impeller with larger blade outlet angle. Blade outlet angle has a certain influence on the static pressure near the long-blade leading edge and tongue, but it has little influence on the distribution of static pressure in the passages of impeller. The experiment results show that the low-specific-speed centrifugal pump with larger blade outlet angle has better hydraulic performance. 相似文献
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War War Min Swe Hiroya Morimatsu Hidechito Hayashi Tetsuya Okumura Ippei Oda 《热科学学报(英文版)》2017,26(3):208-213
The flow characteristics of the centrifugal fans with different blade outlet angles are basically discussed on steady and unsteady simulations for a rectangular casing fan. The blade outlet angles of the impellers are 35° and 25° respectively. The unsteady flow behavior in the passage of the impeller 35° is quite different from that in the steady flow behavior. The large flow separation occurs in the steady flow field and unsteady flow field of the impeller 35°, the flow distribution in the circumferential direction varies remarkably and the flow separation on the blade occurs only at the back region of the fan; but the steady flow behavior in the impeller 25° is almost consistent with the unsteady flow behavior, the flow distribution of the circumferential direction doesn't vary much and the flow separation on the blade hardly occurs. When the circumferential variation of the flow in the impeller is large, the steady flow simulation is not coincident to the unsteady flow simulation. 相似文献
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A numerical investigation on the flow in a bend channel by coupling the impeller with the vaneless diffuser in a centrifugal compressor with different r/b ratios (bend radius r to bend channel width b) is presented. The jet-wake effect of the impeller outlet is considered and flow pattern in the bend channel and the performance of the centrifugal compressor stage are investigated. The results indicate that there is an optimal r/b ratio for increasing the stage efficiency to the highest for a specific compressor stage. The change in r/b ratio significantly affects the flow angle of the bend channel outlet. The prime reason for the total pressure loss in the bend channel is the wall friction in the bend channel. 相似文献