实际风况下萨沃纽斯风力机集群性能及布局规律研究

为探究风况条件对萨沃纽斯风力机集群功率输出和安装方向的影响,基于变转速控制策略和计算流体力学仿真结果,获得了集群在我国8个典型站点不同安装方向下的输出功率,分析了集群在实际风况下的最佳布局规律,并验证了规律的普适性。仿真结果表明:在沈阳、厦门、昆明、呼和浩特、青岛、喀什、大连以及郑州8个站点合理安装集群,可使单台机组的输出功率分别提升至原来的1.14、1.23、1.31、1.20、1.21、1.24、1.12、1.11倍;对于有明显单一主风能风向的地区,集群应正对此方向摆放;对于两个主风能风向相位差较大的地区,需选择两者中周围风能更丰富的方向排布集群;对于有3个主风能风向、主风能风向不明显或风能分布比较均匀的地区,应先使机组相互格挡的方位避开风能相对集中区,再选择风能资源较丰富的方向排布集群。该研究可使实际风况下萨沃纽斯风力机集群耦合增益最大化,并为复杂风场条件下集群安装方向的选择提供参考。

异步反转式组合型垂直轴水轮机性能研究

为了解决升力型垂直轴水轮机因其较低的静力矩而无法应用于低流速海流环境的问题,提出一种内外转子异步反转的组合型水轮机。装置的外部是H型转子,内部采用Savonius型转子,2个转子在各自最优尖速比下运行,在提供运行效率的同时降低系统启动流速。利用CFD软件数值分析内部转子的转速、组合轮机的直径比对外部H型转子及组合轮机性能的影响规律。采用数值计算方法研究组合轮机在不同来流方向的静力矩系数。研究结果表明:当直径比小于0.4时,内部转子的尖速比几乎不影响外部H型转子的效率,但当内部转子尖速比大于0.5时,内部转子转换为耗功部件,组合轮机的效率降低;由于内外转子存在转速差,大直径比组合轮机的内外转子将产生较强的相位干涉,增加外部转子的扭矩波动,会降低组合轮机的寿命。因此,组合轮机的直径比应选择为0.2~0.4,内部S型转子尖速比为0.2~0.5。组合轮机在大部分流动方向下,静力矩系数显著提升。

盐水液滴蒸发析晶实验研究及其反应工程法的单液滴模型

为建立适用于盐水喷雾蒸发数值模拟的单液滴蒸发模型,开展了NaCl溶液的单液滴蒸发析晶研究。首先,搭建了可同时测量液滴质量、温度、粒径的单液滴蒸发可视化实验平台,基于液滴的流致振动特性,提出了利用低通滤波改善振动信号对质量测量影响的方法;其次,开展了初始质量分数为10%的NaCl溶液液滴蒸发实验,明确了盐分析出对液滴温度、粒径和蒸发率的影响规律;最后,基于实验数据,获得了相对活化能和无量纲粒径随液滴干基含水率的变化关系,并建立了NaCl溶液液滴的反应工程法模型。数值模拟结果表明:所提模型预测结果的最大相对误差小于8%。该实验平台可为含析出性溶质液滴干燥过程中的质量测量提供重要借鉴,所提出的反应工程法模型也可用于NaCl溶液喷雾干燥的大规模高效数值计算。

阿基米德水轮机阵列的耦合增益效应研究

为了探究阿基米德水轮机阵列间的耦合增益效应,从而实现对深海超低速海流能的高效利用,对阿基米德水轮机阵列进行了研究,建立了阿基米德水轮机的数值模型,并通过水槽实验验证了模型的可靠性,分析了不同排布方式下轮机的能量利用系数和启动力矩系数。结果表明:当并联阵列间距为1.3倍直径时,受耦合增益效应影响,能量利用系数、启动力矩系数均出现峰值,为并联阵列的最佳距离;当串联阵列间距大于5倍直径时,下游轮机的能量利用系数恢复到孤立轮机的70%以上且恢复趋势变缓,为串联阵列的最佳距离;反向旋转布置的三角形阵列,当列间距为1.2倍直径时耦合增益效果较好,可使能量利用系数提升8%,并获得更大的能量密度。研究结果可为该类型轮机的优化布置策略提供一定的参考。

喷雾蒸发-低温多效蒸馏集成海水淡化系统设计

为了解决目前海水淡化过程中副产高浓度盐水的排放污染问题,设计了喷雾蒸发-低温多效蒸馏集成海水淡化系统。首先建立了进料流量为1kg/s的五效顺流系统相应工艺流程的数学模型,并对其进行了热力和结垢分析,确定了抽汽比例为20%条件下集成系统的运行工况参数;然后基于单个纯水液滴在干空气中的蒸发运动轨迹计算,完成了喷雾蒸发室的初步结构设计;最终采用FLUENT软件对该喷雾蒸发过程进行了非稳态数值模拟,并对粒子停留时间以及蒸发效率进行了分析。结果表明:该套系统必须采用抽汽方式才能有效避免末效结垢情况的发生,喷雾蒸发室内的热质传递在35s左右进入稳态,稳定时物料蒸发效率可以达到82.2%,基本达到了设计初衷。该系统可有效解决浓盐水的排放难题。

Multi-Objective Multi-Variable Large-Size Fan Aerodynamic Optimization by Using Multi-Model Ensemble Optimization Algorithm

The constrained multi-objective multi-variable optimization of fans usually needs a great deal of computational fluid dynamics(CFD)calculations and is time-consuming.In this study,a new multi-model ensemble optimization algorithm is proposed to tackle such an expensive optimization problem.The multi-variable and multi-objective optimization are conducted with a new flexible multi-objective infill criterion.In addition,the search direction is determined by the multi-model ensemble assisted evolutionary algorithm and the feature extraction by the principal component analysis is used to reduce the dimension of optimization variables.First,the proposed algorithm and other two optimization algorithms which prevail in fan optimizations were compared by using test functions.With the same number of objective function evaluations,the proposed algorithm shows a fast convergency rate on finding the optimal objective function values.Then,this algorithm was used to optimize the rotor and stator blades of a large axial fan,with the efficiencies as the objectives at three flow rates,the high,the design and the low flow rate.Forty-two variables were included in the optimization process.The results show that compared with the prototype fan,the total pressure efficiencies of the optimized fan at the high,the design and the low flow rate were increased by 3.35%,3.07%and 2.89%,respectively,after CFD simulations for 500 fan candidates with the constraint for the design pressure.The optimization results validate the effectiveness and feasibility of the proposed algorithm.

Experimental and Numerical Investigations of Shock-Wave Boundary Layer Interactions in a Highly Loaded Transonic Compressor Cascade

Experimental and numerical investigations were conducted to investigate the variations of shock-wave boundary layer interaction(SBLI) phenomena in a highly loaded transonic compressor cascade with Mach numbers.The schlieren technique was used to observe the shock structure in the cascade and the pressure tap method to measure the pressure distribution on the blade surface.The unsteady pressure distribution on blade surface was measured with the fast-response pressure-sensitive paint(PSP) technique to obtain the unsteady pressure distribution on the whole blade surface and to capture the shock oscillation characteristics caused by SBLI.In addition,the Reynolds Averaged Navier Stokes simulations were used to compute the three-dimensional steady flow field in the transonic cascade.It was found that the shock wave patterns and behaviors are affected evidently with the increase in incoming Mach number at the design flow angle,especially with the presence of the separation bubble caused by SBLI.The time-averaged pressure distribution on the blade surface measured by PSP technique showed a symmetric pressure filed at Mach numbers of 0.85,while the pressure field on the blade surface was an asymmetric one at Mach numbers of 0.90 and 0.95.The oscillation of the shock wave was closely with the flow separation bubble on the blade surface and could transverse over nearly one interval of the pressure taps.The oscillation of the shock wave may smear the pressure jump phenomenon measured by the pressure taps.

Performance-Driven Multi-Objective Optimization Method for DLR Transonic Tandem Cascade Shape Design

Transonic tandem cascades can effectively increase the working load,and this feature conforms with the requirement of the large loads and pressure ratios of modern axial compressors.This paper presents an optimization strategy for a German Aerospace Center(DLR)transonic tandem cascade,with one front blade and two rear blades,at the inlet Mach number of 1.051.The tandem cascade profile was parameterized using 19 control parameters.Non-dominated sorting Genetic algorithm(NSGA-II)was used to drive the optimization evolution,with the computational fluid dynamics(CFD)-based cascade performances correction added for each generation.Inside the automatic optimization system,a pressure boundary condition iterative algorithm was developed for simulating the cascade performance with a constant supersonic inlet Mach number.The optimization results of the cascade showed that the deflection of the subsonic blade changed evidently.The shock wave intensity of the first blade row was weakened because of the reduced curvatures of the optimized pressure and suction sides of the front blade part and the downstream moved maximum thickness position.The total pressure losses decreased by 15.6%,20.9%and 19.9%with a corresponding increase in cascade static pressure ratio by 1.3%,1.8%and 1.7%,for the three cascade shapes in the Pareto solution sets under the near choke,the design and near stall conditions,respectively.

Experimental Investigation of the Transonic Shock Oscillation Characteristics in a Heavy-Duty Gas Turbine Compressor Cascade

This paper presents an experimental study of the self-sustained transonic shock oscillating behaviors in a heavy-duty gas turbine compressor cascade under the inlet Mach number of 0.85,0.90 and 0.95.The transonic shock patterns and the surface flow structures are captured by schlieren imaging and oil flow visualization.The time-averaged and instantaneous transonic shock oscillating behaviors at the near choke point and the near stall point are investigated by the Anodized Aluminum Pressure-Sensitive Paint(AA-PSP)surface pressure measurement.The normal passage shock dominant pattern and the detached bow shock dominant pattern at the near choke point and the near stall point are experimental characterized,respectively.The passage shock oscillation behaviors at the near choke point have been observed to undergo periodic pressure perturbations of the shock shift between the upstreamλshock feet mode and the downstreamλshock feet mode.The detached bow shock oscillation behaviors at the near stall point have been observed to undergo the pressure perturbations of the shock cycle movement between the upstream detached bow shock mode and the downstream detached bow shock mode.The differences between the shock shift mode and the shock cycle movement mode lead to the different streamwise oscillation travel ranges and different shock intensity variations under the same inlet Mach number.