600MW汽轮机调节级优化设计

本文对哈尔滨汽轮机厂600MW汽轮机调节级的优化设计进行了总结。在优化设计调节级喷嘴叶片时,采用了端壁子午面收缩和叶片切向弯曲两项新技术。运用全三元势函数程序对平行端壁、端壁子午面收缩和端壁子午面收缩加叶片切向弯曲三种叶栅的三元流场情况进行了计算,分析了端壁子午面收缩以及端壁子午面收缩加叶片切向弯曲时流场的影响和采用这两项新技术降低损失的机理,并根据实验结果对最终优化设计方案的损失进行了估算。     

加压气固喷射器输送特性的试验研究

在增压气力输送系统试验装置上,对影响收缩型气固喷射器的工作特性的关键因素做了较详细的研究,试验研究结果表明,气体喷嘴位置和收缩段的收缩角对气固喷射器的最大固体输送量均有较大的影响,此外,气体喷嘴位置以及收缩段的收缩角对收缩型气固喷射器内的静压分布也均有一定的影响。     

自收缩对地下室长墙早期应力的影响

自收缩是影响混凝土抗裂性能的一个重要参数,采用三维混凝土温控防裂有限元程序,分析了不同收缩终值、收缩速率对某工程地下室长墙早期应力的影响。结果表明,墙体早期应力对自收缩终值和自收缩发展速率的影响均十分敏感,较大自收缩终值在墙体后期易产生较大拉应力,而较大自收缩发展速率早期易产生较大应力,且拉应力龄期提前,在实际工程中应采取相应措施以减小自收缩、控制其发展速率,从而减小墙体出现裂缝的可能性。     

加压气固喷射器内静压分布特性的试验研究

在增压气力输送系统试验装置上,对影响收缩型气固喷射器内静压分布特性的关键因素作了较深入地研究。试验研究结果表明,静压在气固喷射器收缩段入口处明显急剧上升。气固喷射器内静压随气体喷嘴位置S的增大而减小,而随收缩角α的增大而有所提高。提高气体喷嘴出口速度,气固喷射器内的最大静压值由喷射器收缩段入口处附近迁移至喷射器收缩段出口处附近。此外,气体喷嘴位置、收缩段的收缩角和输送风对收缩型气固喷射器内的静压分布的影响还与系统背压相关联。     

掺合料对混凝土收缩影响及收缩模型分析

针对高性能混凝土添加掺合料后早期收缩变形较普通混凝土复杂,研究了矿渣、粉煤灰、硅粉、减缩剂、减水剂对高性能混凝土收缩的影响,建立了混凝土施工期应力计算收缩模型,并与常用收缩模型进行了对比分析。结果表明,该模型更适合高性能混凝土收缩变形计算。     

具有收缩出口结构的新型循环流化床锅炉的试验研究

通过在冷态循环流化床模型上进行的大量试验研究,提出了强化循环流化床锅炉出口端头效应的方法,分析了收缩出口结构可以强化循环流化床锅炉出口端头效应的机理。结果表明：收缩出口结构的收缩度对循环流化床锅炉流动特性和传热特性的影响存在一个最佳值,一般最佳收缩度与循环流化床锅炉当量直径之比为0．5。这一新发现对循环流化床锅炉的设计和运行有着重要的意义。图9参5。     

端壁收缩对环形叶栅气动性能影响的数值研究

采用数值计算软件Numeca模拟了汽轮机低展弦比端壁收缩喷嘴中气动性能和二次流涡系的发展,并与相同边界条件下的平直端壁喷嘴比较,得到了端壁收缩对流场性能的影响.结果表明:在端壁收缩喷嘴中,较大的进口面积使得马蹄涡发展较弱,顶部区域显著的后加载特性更进一步抑制了顶部通道涡的发展,因此通道涡尤其是上通道涡的尺度和损失均较小.同时,顶部收缩导致了顶部气流出气角增大和根部出气角减小,虽然变化幅度不大,但是气流角沿叶高的分布更加均匀,对下排叶栅内的流动更加有利.另外还计算了不同高度收缩比喷嘴流动,给出了高度收缩比对叶栅流动的影响.     

反弧段急变流收缩断面水深计算方法

针对反弧段急变流收缩断面水深的计算问题,基于其动水压力分布规律,分析了考虑离心力作用项与常规计算所得的收缩断面水深的差异,并采用牛顿迭代法推导出考虑离心力作用项的收缩断面水深的迭代计算公式。同时,由水工模型试验验证了计算结果的合理性和准确性。     

簸萁形进水流道进水收缩段底面倾角对流道水力性能的影响

为了探究簸萁形进水流道进水收缩段底面倾角对流道水力性能的影响,建立了簸萁形进水流道的进水结构物理模型和水动力学模型,采用雷诺N-S方程和RNGκ-ε湍流模型,对进水收缩段5种不同底面倾角的流道水流流场进行数值模拟。结果表明,底面倾角对流道进水收缩段和喉部的流速分布影响较大,较大的底面倾角使进水收缩段的流线分布密集度和喉部流线弯曲度增大、流速升高,增大了流道水力损失,降低了流道出口断面流速分布的均匀度;较小的底面倾角使进水收缩段的流线分布平顺和喉部流线弯曲度变缓、流速降低,减小了流道水力损失,提高了流道出口断面的流速分布均匀度;进水收缩段底面倾角的大小对流道出口断面的水流速度加权平均角无明显影响;分析不同底面倾角的流道水力性能,在簸萁形进水流道的进水收缩段底面倾角≤3°时,进水流道的水流平顺,水力损失小,流道出口的水流流态满足水泵叶轮室进口的进水条件。     

规则波作用下收缩波道波浪集聚行为的数值研究

建立规则波作用下收缩波道波浪集聚行为的三维水动力数学模型,与室内试验数据进行有效验证。利用验证后的模型对不同波浪参数、不同几何尺寸收缩波道的波浪集聚行为进行计算分析,结果发现:随着收缩角的增加,波高集聚系数先增后减,在60°达到最大;随着收缩波道长度的增加,波高集聚系数增加;随着收缩口门宽度和入射波高的增加,波高集聚系数均相应减小。基于量纲分析方法和最小二乘法,拟合并验证由收缩波道相对长度,相对入射波高和收缩角弧度表示的波高集聚系数公式。     

Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.     

Wind power for pumping: The development of the ITP windpump

Water pumping has been one of the main applications for wind power in the past and despite the spread of mains-electric pumps, more than a million windpumps remain in regular use. This paper reviews the general technical and economic requirements for pumping water using wind energy and by way of example gives an overview of the development of the new ITP wind-pump. It then considers the future prospects for this kind of technology.     

Methods of creating solar-reflective nonwhite surfaces and their application to residential roofing materials

We describe methods for creating solar-reflective nonwhite surfaces and their application to a wide variety of residential roofing materials, including metal, clay tile, concrete tile, wood, and asphalt shingle. Reflectance in the near-infrared (NIR) spectrum (0.7–2.5 μm) is maximized by coloring a topcoat with pigments that weakly absorb and (optionally) strongly backscatter NIR radiation, and by adding an NIR-reflective basecoat (e.g., one colored with titanium dioxide rutile white) if both the topcoat and the substrate weakly reflect NIR radiation. Coated steel and glazed clay-tile roofing products achieved NIR reflectances of up to 0.50 and 0.75, respectively, using only cool topcoats. Gray-cement concrete tiles achieved NIR reflectances as high as 0.60 with coatings colored by NIR-scattering pigments. Such tiles could attain NIR reflectances of up to 0.85 by overlaying a white basecoat with a topcoat colored by NIR-transparent organic pigments. Granule-surfaced asphalt shingles achieved NIR reflectances as high as 0.45 when the granules were covered with a white basecoat and a cool color topcoat.     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

Thermal decay of an initially hot isothermal water body with application to thermal energy storage

The thermal decay of an initially hot isothermal water body contained in a tank was studied. Analytical solutions (including a group-theoretic solution) were obtained for the one-dimensional heat conduction equation with heat loss from the sides of the tank. The convective heat transfer coefficient was assumed not to be constant over the surface of the tank but to vary with space and time. A very good agreement was obtained between the group-theoretic solution and a numerical solution using the Crank-Nicholson finite difference scheme. The analytical results are discussed in terms of the underlying physical mechanisms.     

秸秆燃烧中温度对钾转化与释放的影响

通过对稻秆原料进行常规特性分析和EDX元素含量分析,发现钾在稻秆无机元素中占有重要地位。参考原料化学分馏法和土壤中钾的分类与测试方法,给出了对生物质原料及其燃烧产物中钾的定性与定量简易方法。通过程序控温型固定床对稻秆先进行缓慢氧化,然后以100℃为间隔从400～900℃进行成灰,并分别测试其成灰率、有效钾和全钾的份额。结合稻秆原料及其灰中钾的份额分析,进行了稻秆灰中有效钾转化与释放的计算,发现有效钾在700～800℃之间有快速的释放和形态转变。稻秆灰的XRD分析结果表明秸秆灰中钾主要以KCl、K_2SO_4形式存在,得到了钾以盐的形式进行转化与释放的机理。该文中燃烧温度对钾转化与释放的影响规律对设计秸秆电厂时的炉型选择和燃烧参数确定有一定参考价值。