The Method of Thermoelectric Energy Generations Based on the Axial and Radial Flux Electromagnetic Inductions*

The traditional thermoelectric energy conversion techniques are explained in detail in terms of the axial flux electromagnetic (AFE) and the radial flux electromagnetic (RFE) inductions, and applications to heat engines for the energy-harvesting technologies are discussed. The idea is induced by the analysis of thermomechanical dynamics (TMD) for a nonequilibrium irreversible thermodynamic system of heat engines (a drinking bird, a low temperature Stirling engine), resulting in thermoelectric energy generation different from conventional heat engines. The mechanism of thermoelectric energy conversion can be categorized as the axial flux generator (AFG) and the radial flux generator (RFG). The axial flux generator is helpful for low mechanoelectric energy conversion and activations of waste heat from macroscopic energy generators, such as wind, geothermal, thermal, nuclear power plants and heat-dissipation lines, and the device contributes to solving environmental problems to maintain clean and sustainable energy as one of the energy harvesting technologies.

The Axial and Radial Solid Loadings up the CFB-Riser

1 INTRODUCTIONThe determination of the solids hold-up and local solidfluxes is of paramount importance in the study ofthe hydrodynamics of a two-phase flow.Several tech-niques have been used during the past decades(Table1).These methods can be classified in two groups,depending on their possible disturbance of the two-

Novel transit-time oscillator(TTO) combining advantages of radial-line and axial TTO

A novel transit-time oscillator(TTO)is proposed in this paper.An axial cathode which has been widely used in high power microwave(HPM)source and an extractor with radial feature are adopted.In this way,the inherent advantages of axial and radial TTO,both of which can be utilized as high-quality intense relativistic electron beam(IREB),can be generated and the power capacity is also increased.The working mode isπ/2 mode of TM01 based on small-signal theory,and under the same energy storage,the maximum electric field in extractor decreases 16.3%.Besides,by utilizing the natural bending of the solenoid,this TTO saves over 60%of the length required by the uniform magnetic field,and consequently reduces the energy consumed by solenoid.The PIC simulation shows that by using 1.0-T decreasing magnetic field generated by the shorter solenoid,3.37-GW microwave at 12.43 GHz is generated with 620-kV and 13.27-kA input,and the overall conversion efficiency is 41%.

Modeling and Simulation of Radial-Axial Large Ring Rolling

Finite element model is constructed according to the principle and characteristics of radial-axial large ring rolling technology. Dynamic explicit finite element method is used to simulate the rolling process. An effective modeling method of guide roller is proposed. Simulation indicates that high quality ring product could be obtained when rational rotational speed of rollers and feed rate in the radial and axial rolling are assigned.

The Influence of Radial Area Variation on Wind Turbines to the Axial Induction Factor

Improvements in the aerodynamic design will lead to more efficiency of wind turbines and higher power production. In the present study, a 3D parametric gas turbine blade geometry building code, 3DBGB, has been modified in order to include wind turbine design capabilities. This approach enables greater flexibility of the design along with the ability to design more complex geometries with relative ease. The NREL NASA Phase VI wind turbine was considered as a test case for validation and as a baseline by which modified designs could be compared. The design parameters were translated into 3DBGB input to create a 3D model of the wind turbine which can also be imported into any CAD program. Design modifications included replacing the airfoil section and modifying the thickness to chord ratio as a function of span. These models were imported into a high-fidelity CFD package, Fine/TURBO by NUMECA. Fine/TURBO is a specialized CFD platform for turbo-machinery analysis. A code-geomturbo was used to convert the 3D model of the wind turbine into the native format used to define geometries in the Fine/TURBO meshing tool, AutoGrid. The CFD results were post processed using a 3D force analysis code. The radial force variations were found to play a measurable role in the performance of wind turbine blades. The radial component of the blade surface area as it varies in span is the dominant contributor of the radial forces. Through the radial momentum equation, this radial force variation is responsible for creating the streamline curvature that leads to the expansion of the streamtube (slipstream) that is responsible for slowing the wind velocity ahead of the wind turbine leading edge, which is quantified as the axial induction factor. These same radial forces also play a role in changing the slipstream for propellers. Through the design modifications, simulated with CFD and post-processed appropriately, this connection with the radial component of area to the radial forces to the axial induction factor, and finally the wind turbine power is demonstrated. The results from the CFD analysis and 3D force analysis are presented. For the case presented, the power increases by 5.6% due to changes in airfoil thickness only.

轴径向静态偏心故障下外转子永磁发电机电磁转矩特性分析

对外转子永磁发电机轴径向静态偏心故障下的电磁转矩特性进行了理论解析、仿真计算和实验验证。首先,在考虑齿槽效应影响条件下,引入磁导修正系数ε(θ),推导出轴径向静态偏心前后气隙磁密表达式,并考虑绕组分布情况,构建一种新型的永磁发电机轴径向静态偏心故障下相电流数学模型,在此基础上得到轴径向偏心下电磁转矩解析表达式。其次,通过有限元仿真计算得到外转子永磁发电机轴径向静态偏心下的电磁转矩波动特性。最后,在一台外转子永磁发电机上通过故障模拟实验实例印证了解析分析和仿真计算结果。结果表明:相较于正常情况,径向偏心时,电磁转矩以直流、二倍频、四倍频成分为主,随着偏心程度的加剧,电磁转矩的直流、二倍频、四倍频成分幅值将随着增大;轴向偏心时,电磁转矩谐波成分不变,随着偏心程度的加剧,各谐波成分幅值将随着减小。对外转子永磁发电机气隙偏心故障分析的一个重要补充,对此类问题的现场检测和鉴定具有参考价值。

冲击激励下轴线失准转子-磁轴承系统不对中定量研究

为研究和识别转子系统在轴承处发生的平行角度混合不对中,提出一种频谱辨识转子-磁轴承系统固有不对中量大小的方法.采用动量矩定理将圆盘不平衡力对转轴的影响等效到转子轴向力上,建立考虑轴向径向耦合效应的刚性双偏置圆盘转子-磁轴承系统的动力学模型;通过SIMULINK仿真得到系统时域下的位移和电流响应,分析不对中条件下转子系统动力学特性,并利用快速傅里叶变换将时域响应转换为频域响应,基于频域下最小二乘算法得到转子系统不对中量大小.结果表明:在冲击激励影响条件下,采用该方法计算的不对中量大小误差均在5.0%以内,当转子受到外界扰动力时,该算法能够准确定量识别转子的不对中量,可为不对中转子-磁轴承系统故障诊断及自修复提供理论参考.

超大直径铝合金环形锻件轧胀成形工艺与装备关键技术研究

介绍了重载火箭用铝合金大型环形锻件的制作工艺,重点分析了径轴向数控轧制环形锻件的制作工艺。介绍了大型环形锻件轧制和胀形结合成形的制作工艺,采用有限元模拟了Φ10和Φ1.2 m环形锻件的轧制和胀形结合成形工艺过程,并对Φ1.2 m环形锻件的轧制和胀形成形过程进行了试验验证。结果表明:轧制和胀形结合的成形工艺技术能有效地改善产品组织,使组织更致密,提高了产品的晶粒度;轧制和胀形工艺技术能有效地提高产品的屈服强度,从而提高产品的使役性能。胀形工艺对产品有明显的整形作用。在此基础上提出Φ10 m环形锻件径轴向数控轧制和液压胀形结合的成形工艺。

定子通风槽钢结构对提高中型高压电机散热性能分析

为降低YJK450-6、400kW中型高压电机的通风散热性能,本文对该电机不同通风槽钢结构进行了散热性能研究。首先,在现有电机的直线标准型通风结构基础上,提出单列缩放型、双列直线型、双列缩放型3种轴-径向混合通风结构形式;在SpaceClaim软件中建立电机3维温度场数值计算模型,根据基本假设和边界条件结合电机内部热量传递公式计算出电机仿真设置参数,并导入Fluent软件进行仿真模拟,其中,计算温度场所用热源通过AnsoftMaxwell平台计算的电机损耗值获取。其次,通过网格无关性和温升试验验证本文建立的电机3维温度场数值计算模型;通过仿真模拟对比分析3种轴-径向混合通风结构与直线标准型结构对电机流场和温度场的影响;采用正交试验法对轴-径向混合通风结构进行参数优化,得到最佳散热结构和参数方案;进一步探究冷却风速对双列缩放型槽钢的电机换热性能的影响;结合定子绕组温升和电机整体的温升均匀性系数,对最佳散热结构和参数方案电机进行散热效果评价。仿真结果表明:本文建立的计算模型是有效的;双列缩放型通风槽钢结构的各项散热性能指标均最好,是最优通风槽钢结构;径向风道高度为6mm且数量为13的双列缩放型通风槽钢结构为最佳散热结构和参数方案;双列缩放型通风槽钢结构两侧的平均对流换热系数随冷却风速增大而增大,且槽钢迎风面的平均对流换热系数明显大于背风面;径向风道高度为6mm且数量为13的双列缩放型通风槽钢结构电机的内/外层绕组温升分布均匀性系数比直线标准型电机分别提高88.13%、20.11%。因此,优化设计通风槽钢结构有利于电机内部空气流动和散热,可实现有效降低电机内部温升的目的。

高效非晶合金电机关键技术研究综述

非晶合金以其优异的低损耗特性在电机领域受到越来越多的关注。对非晶合金电机的研究进展进行梳理,介绍了非晶合金电机相对传统电机的优势,阐述了现阶段非晶合金电机铁心常用的加工工艺以及非晶合金电机的研发应用情况。对非晶合金电机关键技术的研究现状进行总结,包括考虑加工工艺、装配工艺下非晶合金电机铁心损耗与温升的精确计算,径向磁通与轴向磁通非晶合金电机振动噪声的精确计算,非晶合金电机设计优化与前沿应用,并对非晶合金电机未来发展趋势与研究方向进行了展望。

径轴向聚磁型永磁推进电机优化设计与分析

为了进一步实现永磁电机磁负荷和转矩密度的提升,提出了一种径轴向聚磁型永磁推进电机结构,转子永磁体在Halbach径向聚磁结构基础上进一步结合轴向延伸永磁体,实现了永磁磁场的径轴向聚磁。针对该种新型电机,本文详细研究了其结构特点,利用有限元分析了所提电机结构的电磁性能。首先对比分析了定转子等长结构、定转子不等长(overhang)结构输出性能,并对对称型overhang结构进行了参数化优化,有效提升了电机转矩密度。最后,利用三维有限元模型对比分析了径向overhang和径轴向overhang电机的电磁性能,结果发现径轴向overhang电机空载磁密提升了6%、输出转矩增大了1.3%、转矩脉动减少了0.4%,进一步验证了电机性能的优越性。

大功率磁悬浮泵宽流道叶轮的水力性能分析

磁悬浮泵将磁悬浮电机与泵体结构一体化,利用磁场驱动叶轮旋转,并对其余5个自由度进行主/被动悬浮约束,从而实现完全无轴承的介质泵送,被广泛用于半导体制造等领域的电子化学品超洁净输送。目前,大功率磁悬浮泵产品存在泵送效率低的问题,同时随着功率的增加,磁悬浮泵的液压轴向力平衡问题越发突出。为此,设计了一种大功率磁悬浮泵的宽流道叶轮,并对其进行水力效率、液压轴向力及液压径向力分析。通过仿真研究,首先阐述了窄流道效应对大功率磁悬浮泵水力效率的影响,并对宽流道叶轮及窄流道叶轮进行水力效率对比分析;其次对宽流道叶轮的液压轴向力及径向力进行计算分析,表明宽流道设计对叶轮液压轴向力及径向力的影响,为大功率磁悬浮泵高效水力设计开发提供关键技术支撑。

水下S-CO_(2)循环部分进气轴/径向涡轮机对比研究

将超临界二氧化碳(S-CO_(2))循环动力系统合理应用于无人水下航行器(UUV),有助于解决现有UUV蒸汽动力循环系统尤其是针对小功率等级应用效率低的问题。为合理选型水下S-CO_(2)系统涡轮机,结合损失模型的一维方法获得了设计空间内的最佳几何参数,并基于RANS方程的三维数值仿真方法验证了一维设计方法的合理性,进一步对比分析了轴/径向涡轮机的气动性能及流动特性。结果表明,设计工况下径向涡轮机内效率比轴向涡轮机高5.41%,但尺寸较大,约为轴向涡轮机的2倍;径向涡轮机的主要损失集中在喷管和转子非工作段,而轴向涡轮机则主要为转子处产生的二次流损失。通过变工况分析发现,轴向涡轮机更适用于低速比工况,但在同一转速下径向涡轮机效率更高。文中研究结果可为应用于UUV的S-CO_(2)系统动力主机的研制提供参考。

大配合间隙下阀芯偏斜对水嘴性能的影响

水嘴作为配水器的核心组件,目前已被广泛应用于注水油田。然而,水嘴在实际应用中会遭遇卡阻,导致阀芯无法正常调节,影响注水的效果。并且在测试过程中,很难观察到阀芯卡阻的细节,并重现这种现象。为了揭示水嘴卡阻机理,对不同开度下大配合间隙、阀芯偏心及倾斜对水嘴性能的影响进行了研究。首先,利用了仿真计算方法,建立了水嘴流体域有限元模型,构建了水嘴理论流量特性计算模型,通过实验获得了流量特性,验证了有限元模型的准确性;然后,分析了不同配合间隙下水嘴的流量特性及阀芯表面压力特征,获得了水嘴关闭时的泄漏量、阀芯受到的轴向力和径向力以及表面流动特征;最后,利用了遗传算法,优化了配合间隙。研究结果表明:大配合间隙使流量调节率曲线明显偏离标准曲线,流量调节率明显降低;水嘴在零开度时的径向力与轴向力最大;当配合间隙为0.05 mm时,泄漏量比间隙为0.25 mm时减少了84.56%;配合间隙对泄漏量的影响最为显著,其次为径向力和轴向力;优化配合间隙能够降低泄漏量和径向力,增大偏心与倾斜角能够降低卡阻风险,提高水嘴运行的可靠性。

齿轮泵内部间隙泄漏的研究综述

在高压状态下,齿轮泵内部间隙增大会加剧泵内泄漏,严重影响其容积效率。首先介绍轴向间隙和径向间隙是造成泵内泄漏的2条主要途径,分析2种间隙内液体泄漏量与间隙值的数学模型。接着介绍轴向间隙的主要影响因素包括:齿轮轴挠度变形、齿轮轴偏心和泵体磨损与结构变形;而径向间隙主要被齿轮泵端盖变形和多物理场耦合作用所影响。为了控制泵内间隙泄漏量,总结了优化和控制内部间隙的研究内容。最后指出了齿轮泵间隙的局部大小变化,对研究泵的流量特性和内部结构设计有重要的参考意义。

复合材料桨叶静力矩测量影响因素研究

为了解决复合材料桨叶的静力矩测量结果差异较大、难以完成准确合格性判定等问题,采用基于天平基本理论的控制变量法对多组桨叶的静力矩展开研究。通过分析造成实验数据差异的原因,结合测量设备本身的精度,发现了对测量影响较大的关键因素,并进行了定量分析计算。通过对比实验,证明了对大轴线力矩测量影响最大的是定位面与测量刀口之间的距离以及其平面加工精度;对小轴线力矩测量影响最大的是对桨叶特定截面的角度测量精度。本研究为后续螺旋桨设计、生产、维修提供了工艺优化的理论和数据基础,对后期新型桨叶的研发具有重要意义。

薄壁圆环件装夹变形理论分析与仿真预测

薄壁圆环类零件广泛应用在离心压缩机设备中,在车削加工中由于装夹力的影响会发生弹性变形,从而影响工件加工精度,为探究零件装夹变形影响,保障离心压缩机运行效率,通过理论分析与有限元仿真模拟相结合的方法,分别建立了薄壁圆环零件在卧式车床四爪卡盘装夹下的理论变形模型和有限元仿真模型进行优化研究。通过两种模型对比可知:有限元仿真模型变形结果与理论模型变形结果较为一致,得出薄壁圆环件普通装夹径向变形较为敏感。据此,提出轴向装夹和均布式径向装夹两种优化装夹方案来减小薄壁圆环件在加工过程中的径向变形,通过计算可知,该两种装夹方式都可有效减小薄壁圆环类零件装夹变形,为提高薄壁圆环类零件加工精度提供理论基础。

Two-dimensional investigation of characteristic parameters and their gradients for the self-generated electric and magnetic fields of laser-induced zirconium plasma

Two-dimensional diagnosis of laser-induced zirconium(Zr)plasma has been experimentally performed using the time-of-flight method by employing Faraday cups in addition to electric and magnetic probes.The characteristic parameters of laser-induced Zr plasma have been evaluated as a function of different laser irradiances ranging from 4.5 to 11.7 GW cm-2 at different axial positions of 1–4 cm with a fixed radial distance of 2 cm.A well-supporting correlation between the plume parameters and the laser-plasma-produced spontaneous electric and magnetic(E and B)fields was established.The measurements of the characteristic parameters and spontaneously induced fields were observed to have an increasing trend with the increasing laser irradiance.However,when increasing the spatial distance in both the axial and radial directions,the plasma parameters(electron/ion number density,temperature and kinetic energy)did not show either continuously increasing or decreasing trends due to various kinetic and dynamic processes during the spatial evolution of the plume.However,the E and B fields were observed to be always diffusing away from the target.The radial component of electron number densities remained higher than the axial number density component,whereas the axial ion number density at all laser irradiances and axial distances remained higher than the radial ion number density.The higher axial self-generated electric field(SGEF)values than radial SGEF values are correlated with the effective charge-separation mechanism of electrons and ions.The generation of a self-generated magnetic field is observed dominantly in the radial direction at increasing laser irradiance as compared to the axial one due to the deflection of fast-moving electrons and the persistence of two-electron temperature on the radial axis.

Effects of Interaction between Axial and Radial Secondary Air and Reductive Intensity in Reduction Region on Combustion Characteristics and NO_(x) Emission of Coal Preheated by a Self-Preheating Burner

The study focused on the effects of the interaction between axial and radial secondary air and the reductive intensity in reduction region on combustion characteristics and NO_(x) emission in a 30 kW preheating combustion system.The results revealed that the interaction and reductive intensity influenced the combustion in the down-fired combustor(DFC) and NO_(x) emission greatly.For the temperature distribution,the interaction caused the position of the main combustion region to shift down as R_(2-12)(ratio of axial secondary air flow to radial secondary air flow) decreased or λ_(2)(total secondary air ratio) increased,and there was the interplay between both of their effects.As R_(3-12)(ratio of first-staged tertiary air flow to second-staged tertiary air flow)increased,the decrease in the reductive intensity also caused the above phenomenon,and the peak temperature increased in this region.For the NO_(x) emission,the interaction affected the NO_(x) reduction adversely when λ_(2) or R_(2-12) was higher,and the range of this effect was larger,so that the NO_x emission increased obviously as they increased.The decrease in the reductive intensity caused the NO_(x) emission increased under the homogeneous reduction mechanism,while was unchanged at a high level under the heterogeneous reduction mechanism.For the combustion efficiency,the interaction improved the combustion efficiency as λ_(2) increased when R_(2-12) was lower,while reduced it as λ_(2) increased excessively when R_(2-12) was higher.The proper decrease in the reductive intensity caused the combustion efficiency increased obviously,while was hardly improved further when the intensity decreased excessively.In this study,the lowest NO_(x) emission was only 41.75 mg/m^(3) without sacrificing the combustion efficiency by optimizing the interaction and reductive intensity.

LVDT重复性影响因素及优化方法研究

针对LVDT在使用中重复性受外界因素影响的问题,进行了理论分析与软件仿真,认为LVDT的铁心受干扰时会产生径向跳动,从几何关系与磁场两方面使测量结果产生误差。文中设计了LVDT重复性测试系统,在LVDT量程范围内选取5、15、25 mm 3个测量点进行测试,结果表明理论分析与实际测试具备良好的一致性。为提高LVDT的重复性,提出用精密直线轴承限制LVDT铁心的径向运动。优化后,5、15、25 mm处测量值的重复性标准差分别从0.07323、0.12633、0.15966 mm降低到0.03757、0.04868、0.04301 mm,测量值的离散程度明显减小,验证了优化方法的可行性和有效性。