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微型轴流风扇中变环量指数对扭叶片气动性能的影响特点 总被引:4,自引:1,他引:3
对微型轴流散热风扇叶片扭曲规律进行研究,根据"径向平衡原理",通过引入一反映气动特性的参数-变环量指数α,建立轴流叶轮中通流速度沿径向分布的微分方程及其边界条件,提出在几类不同条件下该方程解的解析形式,并分析这些解所对应的物理意义及其叶片扭曲形式.在此基础上,根据微型轴流风扇实际运行工况的特点,提出其扭叶片设计中变环量指数α所须满足的约束条件,并指出该变环量指数α存在一个最小值,具体数值则确定于风扇的气动、几何等参数.运用"计算流体动力学"(Computational fluid dynamics,CFD)技术详细地数值研究变环量指数α对微型轴流风扇气动性能的影响,发现降低变环量系数能增加风扇气动性能.进而有助于提高其散热能力.因此,满足约束条件下的最小变环量指数是微型轴流风扇扭叶片气动设计中所须选取的最佳值. 相似文献
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通过推导微型轴流风扇叶片出口轴向速度沿叶高的分布方程,提出了一种考虑轴向速度非均匀性的扭叶片设计方法.通过CFD技术,数值研究了利用该方法所设计的各种形式扭叶片的气动性能及其变工况时的气动特点,并比较了工作于"自模区"与"非自模区"风扇的气动性能的差异.研究结果表明:与"自模区"的风扇相比,就"非自模区"的风扇而言,压力曲线没有最高压力点,随流量减少而压力几乎呈线性增加,且无失速点.效率曲线则显得更为平坦;按"刚性涡"设计的扭叶片虽效率低,但风压高;提高叶轮的轮毂比有助于提升风扇压力与效率. 相似文献
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王鑫 《机械设计与制造工程》2018,(6)
为研究Re数对小尺寸离心叶轮模化设计的影响,利用相似原理,结合计算流体动力学(CFD)进行分析,将某小尺寸离心叶轮分别缩小及放大5倍,获得了该叶轮效率损失和Re数之间的指数关系式,并对绝热条件下缩小叶轮及放大叶轮指数关系式中指数n的大小进行了分析比较。研究结果表明:对于放大叶轮,指数n的数值要高于缩小叶轮,Re数在模化设计过程中的影响更显著一些。该研究结果可为小尺寸离心叶轮的模化设计提供参考。 相似文献
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增加减速比可以实现齿轮驱动风扇的转速变化。降低风扇转子转速,有利于降低风扇噪声和转子结构强度要求。应用一种大弯度低损失扩压叶型,进行大涵道比风扇转子气动设计,以降低风扇转子转速。由于该叶型弯度大,可实现超高载荷;构成的叶栅通道后部呈收敛状,可抑制附面层增厚,降低损失。风扇气动设计采用S1/S2两类流面设计方法,结合多点优化,所设计的超高载荷转子设计点效率为0.964 4,级压比达到要求(1.35),级效率为0.900 2、级喘振裕度46.19%。 相似文献
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介绍一种利用气冷式冷板作为密闭机箱的侧板,使机箱的侧壁成为一种换热系数较高的热交换器的设计,该设计有效地解决了密闭机箱的散热问题。 相似文献
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Response surface method-based optimization of the shroud of an axial cooling fan for high performance and low noise 总被引:1,自引:0,他引:1
Guangzhi Ren Seung Heo Tae-Hoon Kim Cheolung Cheong 《Journal of Mechanical Science and Technology》2013,27(1):33-42
We optimized the shroud of an axial cooling fan in a mechanical room of a household refrigerator using the response surface method (RSM) based on numerical predictions in terms of high flow rate and low noise. Computational fluid dynamics (CFD) techniques and an acoustic analogy were used to predict the volume flow rate (VFR) and noise in the system. The numerical methods were validated by comparing their VFR and acoustic power level predictions with the measured data. Then, the RSM was used to optimize the design parameters of the shroud of an axial cooling fan. The numerical prediction using optimum design obtained for maximum VFR from the RSM showed that the VFR can be increased by 21.8% at the cost of an increase in the acoustic power level by 1 dB. The prediction for minimum noise reveals that the acoustic power level can be reduced by 3.55 dB at the same flow rate as the original model. The orifice length of the shroud and the serrated structure are found to contribute significantly to the flow rate and radiated noise, respectively. Physical reasons for these observations are given based on detailed investigations of the variations of flow fields due to the design parameters. 相似文献
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核电厂冷端优化设计过程中,冷却塔热力计算模块是一个非常重要的计算环节,冷却塔热力计算结果直接影响到凝汽器的性能计算、汽轮机微增功率与热耗特性,从而影响整个冷端系统的优化结果。针对我国核电厂冷端优化设计过程中遇到的冷却塔热力性能计算问题,以湖南桃花江核电工程为例,对比分析了拟二维模型同焓差法、压差法计算结果差异以及淋水面积、冷却水量、冷却温差等设计参数对冷却塔热力计算结果的影响。结果表明,当淋水面积较大,冷却温差较低时,拟二维模型与目前广泛应用的焓差模型、压差模型计算结果偏差较大,建议在拟二维模型应用于工程设计之前,需要进行更为细致的研究以保证其准确性。 相似文献
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K. M. Au K. M. Yu 《The International Journal of Advanced Manufacturing Technology》2013,66(1-4):311-324
Blow moulding is one of the most important polymer processing technologies to produce hollow-shaped parts at a short time. The cooling stage takes up approximately two thirds of the complete blow moulding cycle. It becomes the major factor to determine the productivity and the quality of the blow-moulded part. The cooling time and the quality part are controlled by an adequate cooling channel design inside the blow mould. Inappropriate cooling channel design will increase the cooling time after part ejection. Recently, the success of integrating conformal cooling channel (CCC) design in the injection moulding process has been proven by different research publications and practices. The merit of the applications of CCC can also be extended to the existing blow moulding process. In this study, an effective design method is proposed for integrating CCC into the blow mould with the aid of computer-aided design and analysis tools. The fabrication of integrating CCC into the blow mould by rapid tooling technology is explored. Computer-aided engineering simulation is employed to verify the cooling performance of the CCC corresponding to the blow mould surface geometry. The analysed results are compared with those using the traditional straight line-drilled cooling channel (SLDCC) used in the blow moulding process. The results indicated that the cooling time and temperature uniformity of the blow-moulded part can be effectively improved. The proposed CCC design has a shorter cooling time and a lower part temperature than the SLDCC one. 相似文献
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A. B. M. Saifullah S. H. Masood I. Sbarski 《The International Journal of Advanced Manufacturing Technology》2012,62(1-4):123-133
In injection moulding process, cooling time greatly affects the total cycle time. As thermal conductivity is one of the main factors for conductive heat transfer in cooling phase of IMP, a cooling channel made by higher thermal conductive material will allow faster extraction of heat from the molten plastic materials, thus resulting in shorter cycle time and higher productivity. The main objective of this paper is to investigate bi-metallic conformal cooling channel design with high thermal conductive copper tube insert for injection moulds. Thermal–structural finite element analysis has been carried out with ANSYS workbench simulation software for a mould with bi-metallic conformal cooling channels and the performance is compared with a mould with conventional straight cooling channels for an industrial plastic part. Experimental verification has been carried out for the two moulds using two different types of plastics, polypropylene (PP) and acrylonitrile butadiene styrene, in a mini injection moulding machine. Simulation and experimental results show that bi-metallic conformal cooling channel design gives better cycle time, which ultimately increases production rate as well as fatigue life of the mould. 相似文献