行波波长及波速对获能特性的影响

在一定的运动参数条件下,行波运动可以从流水或风中吸取能量。以NACA0012翼型作为行波运动鱼体二维简化模型的原始翼型,采用数值模拟的方法研究波长及波速对行波运动获能特性的影响。结果表明：当波长不变时,随着无量纲波速的增大,行波运动从流水中吸收的能量（无量纲侧向功率）和能量利用率先增大后减小,并存在一个最佳波速使得无量...     

钝尾缘对扑翼获能特性的影响

扑翼获能器是一种通过升沉俯仰运动从海流中提取能量的装置。采用计算流体力学（CFD）方法对钝尾缘扑翼获能特性进行数值模拟计算,探究钝尾缘对称加厚初始位置、钝尾缘对称加厚厚度与翼型厚度对钝尾缘扑翼获能特性的影响规律。结果表明,钝尾缘对称加厚初始位置与翼型弦长之比p/c=0.90时,钝尾缘控制策略的获能效果较明显。钝尾缘对称加厚厚度对扑翼获能特性的影响主要体现在中高缩减频率,总体来看扑翼获能效率随钝尾缘对称加厚厚度增大呈现先增大后减小的趋势,当钝尾缘对称加厚厚度与翼型弦长之比l/c=0.02时,钝尾缘扑翼获能效率的提升效果达到阈值。随着翼型厚度逐渐增大,钝尾缘扑翼的获能效率先增大后减小,并且当翼型为NACA0030时,获能效率达到峰值。     

振动膜片的流动控制机理研究

采用计算流体力学方法,研究了主流风速为10 m/s,翼型弦长雷诺数为1.2×10~5条件下振动膜片对NACA0012翼型在18°攻角深失速下流动分离的影响。研究表明:振动膜片能明显提高翼型升力系数、降低阻力系数、改善流场状况;当无量纲频率处在1~1.5范围内时,翼型升阻比可大幅提升,最大可提高75.7%;无量纲振幅对翼型升阻比的影响也很显著,相对于原型存在一个最佳的振幅使得翼型升阻比能获得最大提升;不同振幅下,最佳升阻比对应的无量纲频率随振幅增大而减小。     

雷诺数对扑翼获能特性的影响

采用团队自行研发的计算流体力学软件UCFD,研究雷诺数、无量纲频率和俯仰幅值对于扑翼获能特性的影响,分析翼型附近的流场以及涡结构的生成与发展过程,探究扑翼的获能机理。结果表明:随着雷诺数的增加,获能效率增大,高效工况区也增大,但当Re5×10~6时,获能效率趋于稳定。此外,不同雷诺数下高效工况的获能机理并不相同,对于低雷诺数,主要是翼型合理利用大尺度前缘涡;对于高雷诺数,则是利用较高的升沉力做功能力;对于中等雷诺数,以上2种高效机理均存在,且2种高效工况对应的效率相近。     

后掠式水平轴潮流能水轮机的载荷与获能特性研究

针对双向潮流能有效利用问题,设计一种基于对称翼型的新型后掠式水平轴潮流能水轮机,并研究其水动力性能。根据对称翼型升阻力特性与叶片展向攻角变化,采用变截面设计优化后掠式对称翼型叶片,并基于Buhl修正模型分析不同后掠偏移叶片所受推力与获能特性。通过3D建模与水槽实验,研究不同后掠偏移叶片的载荷与获能情况。模型实验研究表明,同一尖速比下,后掠偏移量为10%和15%的水轮机相对于偏移量为5%的水轮机所受推力最大分别降低4%和13.3%,获能效率最多分别减小3.8%和11.1%,其中推力比获能效率减幅更大。实验结果与理论分析变化趋势吻合,但减幅比理论值偏高。此外,该水轮机3种后掠偏移量下对应获能效率随桨距角的增大分别降低18%、14%和6%,获能效率下降显著,与300 kW样机实海况运行情况变化趋势相同。     

基于DES方法的变形叶片气动性能数值模拟研究

针对适用于垂直轴风力机的叶片,以NACA0012作为基准翼型,采用DES湍流模型,在来流雷诺数Re=1×106的情况下进行了等厚度翼型中弧线主动变形运动的数值模拟研究。选用弦长c=0.601 m,展向长度B=1 m,攻角α为15°(浅失速攻角)和18°(深失速攻角),变形频率f为0.5,2和5 Hz,变形幅值A〖DD(-*2〗-〖DD)〗为0.1c的参数条件,对比变形翼型与不变形翼型的气动性能。研究表明：在深失速攻角下变形翼型相较于不变形翼型,其升力系数提升52%以上,阻力系数减小64%以上,气动性能可得到有效提升,且变形翼型在特定工况下能有效减小翼型表面分离区及分离涡尺度。     

带局部运动表面翼型的动态失速特性研究

采用数值模拟方法研究了运动表面长度l、速度比k、凹槽深度h和运动表面的无量纲位置s对带局部运动表面的NACA0012翼型动态失速特性的影响,在相同工况下对比了带表面射流与运动表面边界层控制方法(MSBC)对动态失速的控制效果。结果表明：采用运动表面边界层控制方法能够明显改善翼型的动态失速特性;在最优参数组合(s=0.4、l=0.4、k=1和h=0.25 mm)下MSBC翼型的等效升阻比较原始翼型增大了57.10%;当耗能系数较低时,与带表面射流的翼型相比,采用MSBC翼型可以通过较少的局部能量输入,就能达到提高翼型气动效率的目的。     

环量控制扑翼式获能器气动特性的数值研究

提出了一种采用环量控制的新型扑翼获能技术,首先对这种扑翼在不同折合频率下的获能效率进行了数值模拟,并与传统扑翼和表面施加协同射流控制扑翼的获能效率进行了对比,发现不同工况下对翼型尾缘部施加持续射流均能有效改善翼型的气动性能,使扑翼的能量转换效率显著提高,且提升幅度优于协同射流控制方法,表明该方法具有一定的开发应用潜力。此外,针对连续射流能耗较高的缺点进一步改进了射流施加策略,建立了四种不同射流喷射控制模式,对比研究了连续式、方波式、正弦式和三角波式射流模式下扣除射流能耗后采用环量控制扑翼的获能净效率,旨在以获取最高能量转换效率为目标的前提下尽可能降低射流所需能耗。不同射流模式下的能耗分析表明,连续式环量控制模式下所需能耗最高,方波式、正弦式和三角波式的能耗依次次之,因此扣除主动控制射流的能耗后,三角波式射流喷射模式下扑翼的获能净效率最高,比传统扑翼获能效率相比提升幅度最高可达22.2%,更具实际应用价值。     

一种新的风能吸收装置—行波板

提出了一种新型的风能吸收装置——波动板,在一定的来流风速下,利用行波状运动的板,可以从风中吸取能量,将风能转化成机械能。在Re=4×105条件下,采用数值模拟方法研究了波长和振幅对波动板做功系数和风能利用率的影响,结果表明:在一定振幅和波长下,风能利用率和做功系数随着无量纲波速的增加,先增加后减小;在一定无量纲波速和波长下,随着振幅的增加,风能利用率和做功系数逐渐增加;在一定无量纲波速和振幅下,随着波长的增加,风能利用率和做功系数先增大后减小,存在一个最佳的波长可使风能利用率和做功系数同时达到最大值。     

尾缘双穿孔对翼型性能影响研究

相关研究表明多孔尾缘在降低翼型噪声的同时,对其气动性能也有一定影响,且穿孔几何尺寸和位置是影响尾缘翼型噪声与气动特性的重要参数。针对NACA65019翼型,在来流雷诺数Re=2×105条件下,采用计算流体力学方法研究具有不同穿孔孔径和位置的尾缘双穿孔翼型绕流特征和噪声特性,并通过部分实验验证模拟的可靠性。研究结果表明：尾缘双穿孔翼型在小攻角下,升阻比较原翼型有较明显的提升,当来流攻角大于12 °后,升阻比开始小于原翼型;在一定来流攻角范围内,尾缘双穿孔翼型可延迟吸力面分离,降低吸力面边界层厚度;边界层厚度的降幅与穿孔孔径、穿孔位置密切相关,最大可达28.8%。根据相关声学理论模型,分析了穿孔孔径及位置对尾缘双穿孔翼型噪声特性的影响,经数值研究表明：α=6°时,在100~7 kHz频率范围,不同的尾缘双穿孔翼型相较于原翼型噪声降低最高可达10.7 dB;d=1.0 mm和Xc/c=0.82翼型效果最佳。     

丁二烯抽提装置火用平衡分析及节能途径探讨

通过对某丁二烯抽提装置的平衡进行计算,得出了系统、效率及损失.通过对计算的结果进行分析,从装置设计和工艺操作等方面探讨丁二烯装置的节能方向和途径.     

Generalized limits for energy extraction in a linear constant velocity flow field

The Lanchester–Betz limit has long been established as setting an upper bound on the power performance coefficient of an energy extraction device operating in isolation in a linear constant velocity flow field. However, the ideal limiting performance of energy extraction devices operating in conjunction with ducts, diffusers or any systems that further modify inflow local to the plane associated with energy extraction has not been previously established. The present analysis derives the limiting performance in such cases, with the Lanchester–Betz limit emerging as the special case of energy extraction in open flow. The key to this analysis is the characterization of an ideal system in terms of the axial induction that would exist at the plane of energy extraction in the absence of the energy extraction system. The concept of an ‘ideal system’ as one that matches the flow field in every state of loading of the energy extraction device is also crucial. Computational Fluid Dynamics (CFD) analysis of a system with a diffuser provides preliminary validation of the new theory. Generalization of the standard blade element theory is outlined, and the implications for the development of a rationalized design approach and optimization of a system with a rotor operating in a diffuser are addressed. The theory has obvious applicability to systems that are purposefully designed to augment flow, but a wider relevance to wind technology in situations where terrain or other wind turbines modify the flow field is also suggested. Copyright © 2008 John Wiley & Sons, Ltd.     

Analysis and assessment of a geothermal based cogeneration system and lithium extraction

This paper presents the thermodynamic analyses for a double flash-binary based integrated geothermal power plant which consists of two steam turbines and one expander in the organic Rankine cycle that uses ammonia as the working fluid and a lithium extraction sub system. The main useful outputs of the plant are electricity, heat for floor heating and lithium carbonate (Li₂CO₃). The aim of this study is to assess the overall system performance energetically and exergetically. Based on the results obtained from this study, the overall energy and exergy efficiencies are 58.41% and 66.63%, respectively. The present results also show that the Li₂CO₃ is produced at the rate of 9.52 × 10⁻³ kg/s. In addition, the effects of changing several important operating parameters and ambient conditions on the energy and exergy efficiencies and the performance of the subsystems are investigated.     

带有射流控制的新型扑翼获能特性数值模拟研究

为了研究扑翼的获能机理，以NACA0012为基准翼型提出了一种添加射流控制的扑翼获能装置，并基于动网格技术进行了数值计算，研究了当雷诺数Re=13 800时射流位置、射流方式等关键参数对扑翼获能效率的影响规律。结果表明，与原型扑翼相比，添加射流控制能够有效提升扑翼的获能效率。另外，采用射流速度遵循正弦规律的新型射流控制方式不仅能增强扑翼运行结构的稳定性，而且能在一定程度上提升扑翼的获能效率。     

Geothermal energy extraction using abandoned oil and gas wells: Techno-economic and policy review

Retrofitting depleted oil wells to extract geothermal energy is considered as one of the promising proposals to extend the overall economic life of oil and gas well. For successful implementation of this initiative, a comprehensive overview covering all aspects of geothermal energy extraction from abandoned oil well should be taken into account including technical, economic considerations as well as regulations and policies of respective local governments. Unfortunately, most reported studies have been focused only on one or two aspects, primarily on technical and economic aspects. Little or no study has focused on the policy sector. Moreover, these findings have been scattered, creating difficulties to extract essential information and dragging further development of the technology. This paper is therefore prepared with the objective to provide a comprehensive overview on the geothermal energy extraction from abandoned oil well, technical challenges in its implementation, economical consideration on the conversion of the well and government policy on energy especially geothermal energy and regulation on the utilization of abandoned oil well. To achieve this objective, extensive literature reviews are conducted with more attention given to recent studies on the field. Challenges on the development of this technology are discussed from technical, economic, and policy perspectives. Based on the identified challenges, required research and development as well as necessary policies for further advancement of this technology are outlined and discussed. By providing this comprehensive information, this review paper may serve as a good foundation and guidelines on the conversion of abandoned oil wells into geothermal energy wells.     

基于田口试验方法和CFD相结合的振荡翼捕能性能的优化研究

为了提升振荡翼的捕能性能,该文采用田口试验和CFD相结合的方法,对决定振荡翼捕能性能的5个特征参数进行优化。结果表明：振荡翼的特征参数对其捕能性能具有重要影响,最优和最差参数组合下振荡翼捕能效率相差137.84%。俯仰中心位置对振荡翼捕能效率影响最大,在试验样机设计中应优先考虑;所研究的5个特征参数对振荡翼捕能性能的影响程度依次为：x_p/c>θ₀>翼型相对厚度>h₀/c>f^*。通过对不同参数组合振荡翼的流场分析发现,特征参数优化的振荡翼产生的涡流始终吸附在翼型表面,从而使振荡翼获得较好的升力特性,进而在升沉运动中捕获更多的能量。     

Combined Process of Solvent Extraction and Gamma-Ray Radiation for the Extraction of Oil from Oil Shale

Abstract

Jordanian oil shale kerogen was studied by using several solvents under the gamma radiation condition to extract oil from shale. According to the result obtained, the possibility to extract oil at room temperature and using solvent was successfully obtained. The solvent used in this research study was water, benzene, acetone and kerosene. Experiments was conducted by using a mixture of solvents such acetone water, benzene-acetone, benzene-kerosene, and benzene, kerosene, water alone without mixing. The percentage of yield was found to be with in the range of 13–67. The result showed that acetone-water solvent mixture with 50% of each (vol%) gives the best results. In this study, the particle size was fixed at 1mm size since there was no effect size on extraction yield percentage.     

600MW超临界汽轮机机组冷端的优化改造

对某发电公司1号超临界机组（600 MW）汽轮机冷端设备老化和双背压凝汽器抽空气系统不合理进行了分析并提出改造和优化方案.通过该机组冷端改造和优化方案的实施,该机组全年真空约提高0.816kPa,降低发电煤耗1.67 g/（kW·h）,节约标煤6 346 t,节约资金561.621万元.通过全年的运行经验表明,该项改造取得了显著的经济效益.     

大型建筑厨房通风节能设计

针对厨房通风设计存在的问题,阐述了通风系统、气流组织形式与风量、热量平衡计算、风管内气流速度等的确定原则和方法,以创造优良的厨房环境,设计出高效节能的通风系统。