燃气轮机涡轮后机匣温度场及应力分析

对某型燃气轮机涡轮后机匣加强筋发生断裂的事故进行了温度场和热应力的有限元分析计算，计算表明，涡轮后机匣表面突遇过冷而产生的巨大温度应力是造成加强筋断裂的根本原因。本文还对涡轮后机匣表面安装隔热附件后的情况进行了分析计算，计算表明，在遇到温度发生突变的不利情况下，隔热附件对涡轮后机匣能起到有效的保护作用。     

一种波瓣式导管在潮流涡轮上的应用研究

导管通过扩压与引射作用提高涡轮的流通率与动能转化率,从而提高涡轮的效率。导管过度扩压将会引起流动分离,降低导管的扩压与引射效果,因此限制了涡轮效率的提高。设计一种具有较强引射作用的扩张导管,导管出口采用波瓣形状;采用CFD方法模拟了不同动能转化率下导管流通率及涡轮总效率的变化曲线,其中,不同动能转化率对应的涡轮工作状态采用激盘模型进行模拟,结果表明,该导管式涡轮理论效率最高可以达到145%。选取涡轮最高效率点对应的动能转化率与导管流通率作为涡轮的设计依据,基于能量守恒定律与叶元体理论设计了一台水平轴涡轮。对该涡轮性能的数值预报结果表明,涡轮输出功率可达到117%。     

机匣处理结构离心压气机喘振裕度提高试验研究

以新建自动控制涡轮增压器试验台架为研究平台,以某新开发高压比离心压气机为原型,开展扩稳试验研究与分析。研究结果表明:消音挡板结构对压比≥3.5工况具有一定的扩稳效果,最大可使喘振流量减小6.4%,流量范围拓宽2个百分点;正向导叶结构在增压压比为2.0~4.5时具有一定的扩稳效果,可使喘振流量减小3.0%~6.6%;机匣处理导叶结构引起压气机效率降低,最大降低幅度为3个百分点;蜗壳A/R值减小,具有一定的扩稳作用,可使压气机压比≤4.5时的喘振流量减小,尤其是最高压比1.5~3.5工况,A/R值减小17%,喘振流量可减少10%以上;TRIM减小对压比≥2.5工况具有一定的扩稳效果,可使喘振流量减小,转速越高减小幅度越大,TRIM值由52减至48时,喘振流量最大减小12%,流量范围最高可拓宽4%。     

考虑扩压段的简单脉冲转换器边界条件处理的方法

论述了应用特征线法计算柴油机排气压力波时地考虑扩压段的脉冲转换器边界条件的处理,脉冲转换器流动非常复杂,在计算中往往忽略在扩压段中的流动特性,这样往往会使涡轮前气体参数计算值与实测值之间产生较大的偏差,而且会对涡轮特性的计算带来不利的影响,用能量微分方程和质量微分方程处理此段流程,使其物理模型更接近实际,计算结果同实测数据对比表明,本方法会使涡轮前参数更趋合理。     

涡轮大扩张过渡段的流动分离与控制数值研究

现代高性能涡轮机械中,研究者一直在努力提高其气动性能,体现在涡轮气动参数设计上就是：每个级利用最大焓降、最小的轴向长度、最少的每排叶片数、设计工况最高的效率。这些气动设计特点使得航空涡轮低压级静叶入口段具有较大的向外扩性,给发动机内外端壁及其高低压过渡段的设计带来了难度。通过数值模拟,探讨了一种减小扩压段流动分离的型线设计方法。     

某型涡轮过渡段机匣子午型线数值研究

为了研究某型涡轮过渡段气动性能,采用数值模拟方法研究了子午型线对某带支板的涡轮过渡段气动性能和流场特性的影响,探讨了四种机匣型线时过渡段及上游高压涡轮的气动参数分布及流动情况,并给出了不同方案时总损失对比分析。结果表明,过渡段机匣子午型线对上游高压涡轮的影响不大,仅方案Case_1的气流角发生了明显变化。由于不同的过渡段子午型线使得流道中的静压分布发生变化,气流逆压梯度的变化引起机匣附近的流动分离改变,进而使得过渡段出口的损失变化,极大地影响过渡段的整体气动性能。     

试论航空发动机涡轮机匣传热分析技术

涡轮机匣主要是航空发动机以涡轮段结构的连接位置作为载体,承担机械负荷、气体压力、热负荷,其所发挥的主要作用是承力。而且,涡轮机匣内部流动通道是航空发动机空气系统的重要组成部分,其主要任务是给冷却空气提供气流运动的有效通道。另外,还需要对涡轮叶尖的运作间隙进行全面控制,并引进冷气,以此进行机匣冷却,从而保证机匣的整体强度与使用寿命。作为冷气通道的主要结构,空气系统在计算时,还应对机匣各部分内的通道流动换热特性做进一步的充分了解,并且机匣的温度分布与叶尖间隙控制之间密切相关,在进行机匣温度计算的时候,还需充分了解换热特性。通过数值仿真与实验系统深入探究了涡轮机匣传热特性,并进一步分析了高压涡轮机匣传热分析技术。     

弹头壳体爆炸成形

爆炸成形是以炸药为能源的一种高速高压的新成形工艺。多年来,我厂(七○三所三○工厂)先后爆炸成功了燃气轮机机组的火焰筒、燃气导管、整流罩和扩压机匣等复杂尺寸形状的零部件,对不锈钢和高温合金零件的爆炸胀形积累了一定的经验。     

多工况下燃气轮机高压涡轮叶顶间隙对涡轮效率的影响

涡轮叶顶间隙影响涡轮气动特性。文中针对某型船用燃气轮机在慢车、0.35、0.50、0.85、1.00、1.05等多个工况,通过有限元计算,研究并分析了不同工况时涡轮叶顶间隙高度对涡轮效率的影响。结果发现当运行工况高于0.85工况时该燃气轮机涡轮叶片与机匣衬环发生碰磨;当工况不变时,控制高压涡轮叶顶间隙高度,发现叶顶间隙每增大0.2 mm,涡轮效率降低约0.4%左右,研究结果对主动间隙控制相关研究提供理论参考。     

机匣切向喷气角对涡轮动叶间隙流动的影响

机匣喷气已被证明是改善动叶流道内二次流分布,提高涡轮效率的有效措施之一。本研究采用数值模拟方法研究机匣切向喷气角度对间隙流动控制的影响。结果显示,当增大机匣切向喷气角时,由于喷气速度在切向上的分量减小,使得喷气孔流体在间隙内轴向上影响范围减小,最大降幅可达50%,导致机匣喷气对间隙流动的阻拦作用降低。同时由于切向角度增大使得上通道涡尺寸增加,涡核强度增大约11%,使得动叶出口截面上流动损失增大。考虑到喷气对动叶输出功的负作用,应当选择适当的切向喷气角度,以达到提高涡轮效率的目的。     

SGT5-4000F燃气轮机气缸温度场及位移场分析

使用有限元方法对西门子SGT5-4000F燃气轮机气缸的温度场及位移场进行计算和分析,并把计算结果和排气扩散段金属膨胀节、透平支撑预紧量及放风冷却管路膨胀节的设计参数进行对比分析,表明采用该计算方法得到的结果对燃气轮机结构设计有一定的指导意义。     

Three-Dimensional Simulation of Nonstationary Flow Phenomena in "Last Stage-Exhaust Hood"Compartment

INTRODUCTIONThemostheavyloadedelementsofnowpathoflargesteamturbinesarelastcompartmentsoflowpressurecylinders,whichconsistoflaststageandex-hausthood-owingtotechnologicalrestrictionsthiselementsoflastcompartmentshavemaximalreservesofitsefficiency,soitsimprovementisactuallypossi-ble.MostofthepublicationsongasdynamicsoflastcomPartmentcolltainmainlythedataabouttheop-erationofstageandexhausthoodunderuniformin-letandoutletconditionsandtheimportantquestionssuchasarangeofapplicabilityofisolatedmode…     

Exhaust hood for steam turbines-single-flow arrangement

In the past, increased attention was given to the development of an optimal shape for the inlet part of LP turbine casings in SKODA POWER. A double-flow design is typically used for high power output turbines. An optimized shape for the internal diffuser has been found, which transforms the kinetic energy of steam into increased pressure, thus effectively increasing the thermodynamic efficiency of the stage. Some conclusions have been drawn from laboratory experiments, others derived directly from on-site measurements at power plants. The conclusions from the development of double-flow turbines form the basis for the design of the single-flow turbine arrangement. Single-flow design is typically used for lower output turbines. There are still some limitations in applying this arrangement. The designer needs to resolve the bearing position and how to ensure access to them. Reinforcing the ribs and supports are used, therefore, to ensure the rigidity of the entire casing. The optimization of the single-flow diffuser shape is therefore the subject of the study presented below.     

Interaction between Struts and Swirl Flow in Gas Turbine Exhaust Diffusers

The increasing use of gas turbines in combined cycle power plants together with the high amount of kinetic energy in modern gas turbine exhaust flows focuses attention on the design of gas turbine diffusers as the connecting part between the Brayton/Joule and the Rankine parts of the combined cycle. A scale model of a typical gas turbine exhaust diffuser is investigated experimentally. The test rig consists of a radial type, variable swirl generator which provides the exhaust flow corresponding to different gas turbine operating conditions. Static pressure measurements are carried out along the outer diffuser walls and along the hub of the annular part and along the centerline of the conical diffuser. Velocity distributions at several axial positions in the annular and conical diffuser have been measured using a Laser Doppler Velocimeter (LDV). Pressure recovery coefficients and velocity profiles are depicted as a function of diffuser length for several combinations of swirl strength, tip flow and strut geometries. The diffuser without struts achieved a higher pressure recovery than the diffuser with struts at all swirl angle settings. The diffuser with cylindrical struts achieved a higher pressure recovery than the diffuser with profiled struts at all swirl angle settings. Inlet flows with swirl angles over 18?affected the pressure recovery negatively for all strut configurations.     

A numerical investigation into the effect of diffusers on the performance of hydro kinetic turbines using a validated momentum source turbine model

Kinetic hydropower involves the use of hydro turbines, submerged within existing currents for power generation. They are applicable to ocean and tidal currents, rivers, and human-made channels. This versatility gives them advantages over conventional hydropower, however they suffer from low power densities. This numerical study investigates the use of diffusers to enhance the performance and viability of kinetic hydro turbines. To simplify the problem, the turbine is modeled as a momentum source region, a strategy that is first validated against Betz theory. The diffuser configuration produces 3.1 times more power than the turbine with no diffuser. A scaling analysis also shows a turbine with a diffuser outperforms a larger size turbine with no diffuser.     

Three—Dimensional Simulation of Nonstationary Flow Phenomena in “Last Stage—Exhaust Hood” COmpartment

Threed-mensional nonstationary model of areodynamical interaction of turbine stage and exhaust hood is realized,based on nonstationary 3D codes for calculation of inviscid transonic flow through stage^[3] and exhaust hodd^[4] which consist of diffuser and space under casing.The codes are built with the use of the explicit Godunov‘s 2nd order difference scheme.Some results of flow simulation through the compartments“Stage-exhaust hodd”，“stage-exhaust axial-radial diffuser”for wide range of volumetric flow rates are represented.     

Influence of rotating wakes on separation in turbine exhaust diffusers

Highly efficient turbine exhaust diffuser cannot be designed without taking into account the unsteady interactions with the last rotating row of the turbine. Former investigations described in the literature show a very high potential compared to that of other parts of turbomachines for improving the diffuser. A scale model of a typical gas turbine exhaust diffuser is investigated experimentally. To investigate the influence of rotating wakes, measurements without a spoke wheel as well as measurements with a variable-speed rotating cylindrical spoke wheel with 2 mm- or 10 mm-spokes simulating turbine rotor wakes were made. Miniaturized 3-hole pneumatic probes as well as a 2D-Laser-Doppler-Velocimeter （LDV） were used to investigate velocity profiles. 122 static pressure tapings were used to measure several axial and circumferential static pressure distributions. Without a spoke-wheel the annular diffuser separates at the shroud for all swirl configurations. For the measurements with the 2 mm spoke wheel, the separating diffuser was unstable while keeping the test rig operating parameters constant. For a non-rotating 10 mm spoke wheel and at rotational speeds less than 1,000 rpm, the annular diffuser separated at the shroud. Increasing the rotational speed of the 10mm spoke wheel, flow did not separate at the shroud and much higher pressure recovery than without spoke wheel has achieved.     

Design and performance analysis of radial-inflow turboexpander for OTEC application

Ocean thermal energy conversion (OTEC) is a potential source of renewable energy. In order to design a turbine for maximizing the output power for very low working temperature application like OTEC, careful one-dimensional design followed by detailed three dimensional simulation is required. In this work a radial-inflow turbine with R-22 as working fluid is designed for a closed-cycle ocean thermal energy conversion plant of 2 kWe capacity. Design speed of the turbine is 34000 rpm. Inlet and outlet temperatures of designed turbine are 24.5 °C and 14 °C respectively. Three-dimensional fluid flow analysis inside the turbine at design and off-design conditions were carried out. Important dimensions of the turbine are: rotor tip and shroud radii of 24 mm and 19 mm respectively; blade widths at rotor inlet and outlet of 6 mm and 11 mm respectively; axial length of 17.5 mm; diffuser of 62 mm long. Volute casing designed has a circular cross section. The importance of the number of blades, blade filleting and stagger angle from the point of view of turbine performance are reported.     

Computational analysis of diffuser-augmented wind turbines

Diffuser-augmented wind turbines are suitable candiates for the generation of electricity from jet-stream winds. A blade element, computational analysis is developed that includes wake rotation effects and blade Reynolds number effects. The influence of the diffuser is allowed for by introducing empirical values for the diffuser efficiency and exit-plane pressure coefficient. Good agreement is obtained for power coefficient and turbine axial velocity with experimental results. The use of screens to simulate the turbine is found to overestimate the turbine output by neglecting blade profile drag but to underestimate turbine output by neglecting favourable rotational influences on diffuser efficiency. Maximum power is delivered with a solidity ratio of 0.10 to 0.15 depending on the aerofoil section used.     

Characteristics of a highly efficient propeller type small wind turbine with a diffuser

We studied the improved effects a diffuser had on the output power of small wind turbine systems, aiming to introduce these systems to radio relay stations as an independent power supply system. A frustum-shaped diffuser was chosen from an economical standpoint and wind speed distribution. The effect the diffuser's shape had on the wind speed was analyzed by simulation and showed that the wind speed in the diffuser was greatly influenced by the length and expansion angle of the diffuser, and maximum wind speed increased 1.7 times with the selection of the appropriate diffuser shape. The wind speed in the diffuser was fastest near the diffuser's entrance. We conducted field tests using a real examination device with a diffuser and confirmed that the output power of the wind power generator increased by up to 2.4 times compared to that of a conventional turbine. Moreover, it was confirmed that the diffuser was especially useful where the wind direction was constant.