蒸汽和空气预旋进气共转盘腔壁面换热研究

为了研究不同冷却介质对燃气轮机预旋共转盘腔换热特性的影响,采用数值计算方法分析了空气和蒸汽2种介质下预旋系统共转盘腔表面的换热过程,对比了2种冷却介质在不同旋转雷诺数、无量纲质量流量和进口总温条件下的换热效果。结果表明:相同无量纲质量流量下预旋进气的转盘冷却效果优于无预旋;不同无量纲质量流量下,蒸汽对共转盘腔表面的换热效果均优于空气;旋转雷诺数在5.5×106~7.2×106内,相同旋转雷诺数下的蒸汽冷却下的转盘平均Nu比空气冷却提高约22%,低旋转雷诺数时2种冷却介质的冷却效果略优于高旋转雷诺数时;不同进口总温下,蒸汽冷却效果仍然优于空气,但随着进口总温的升高其优势逐渐减弱,转盘表面传热平均Nu随预旋进口总温的升高而减小。     

高位进气转静系旋转盘流动与换热的数值模拟

采用扩展混合长度湍流模型和S IM PLE算法,用共轭数值计算的方法模拟航空发动机涡轮盘冷却系统的高位进气、径向出流转静系旋转盘腔模型的流场和温度场,分析了其盘面平均努塞尔数N uav随旋转雷诺数R eω和流量系数Cw的变化。结果表明,随着转速和冷气流量的提高换热得以增强,但在本次计算范围内提高转速对换热的增强幅度小于提高冷气流量对换热的增强幅度。     

同速对转涡轮盘腔内流动和换热特性

为研究对转盘旋转速度对盘腔内换热效果的影响,应用RNG k-ε湍流模型对中心进气、径向出流的同速对转涡轮盘腔内的流动和换热特性进行了数值模拟。揭示了盘腔内气体的流动结构、两盘壁面边界层内的径向速度、换热效率以及壁面温度分布特征,并进一步探究了转盘转速对上述流动和换热特征的影响规律。结果表明:对转盘腔内存在两个反向的回流涡胞,这两个涡胞的相对大小以及相遇的滞止点位置取决于进气惯性力和旋转力的相对大小;转盘近壁面流体径向流动速度与盘壁面的对流传热系数呈正相关变化;对于上游盘,低转速范围时转速对壁面换热影响取决于旋转径向力和进气惯性力对上游盘近壁面流体流动驱动作用的相对大小,高转速范围内增大转速,上游盘壁面传热系数增大,壁面温度降低;对于下游盘,壁面低半径区域的对流传热系数随转速增大而减小,而高半径区域的对流传热系数随转速增大而增大。     

涡轴发动机试车台进气流场不均匀整治技术研究

为了使发动机涡轮前温度能在冬天试验时达到型号规范中规定的要求,涡轴试车台采用进气加温装置来实现发动机进气加温需求,但加温装置在使用时存在温差大、压力损失严重的现象,发动机进口气流出现了温度畸变,降低了发动机喘振裕度。针对此情况,提出涡轴发动机试车台进气流场不均匀整治技术,采用数值仿真方法优化进气加温结构设计,通过试验对出口压力温度进行验证,试验结果表明:该整治技术不但能将发动机进气温差控制在2.2℃以内,还可以有效弥补压力损失,满足型号试验要求,获得了高质量发动机进气品质。     

基于集总参数法的坦克发动机热性能模型

发展了一个基于集总参数法的坦克发动机热性能模型，考虑了发动机燃烧室的传热、发动机主要部件的传热、冷却系统和润滑系统的工作及坦克动力舱内的空气流动，建立了燃烧气体与发动机部件、各部件之间、部件与冷却液、部件与润滑油、部件与动力舱空气之间的热耦合计算公式．对一台坦克涡轮增压柴油机的热性能进行了实例计算，结果证实这个模型可以用于坦克发动机热性能的研究．     

预旋角对径流涡轮背盘射流冷却的影响

采用背盘射流冷却技术对径流式涡轮机热负荷较大的区域进行冷却。采用气热耦合的方法,研究了该冷却技术在预旋角为60°～120°内对背盘冷却特性的影响。结果表明:背盘射流冷却可以大幅提高径流涡轮背盘的冷却效率;预旋角为60°时背盘冷却效果最好,随着预旋角的增加,背盘冷却效果变差;相同径向位置时,冷却系数在0.01～0.02,预旋角每增加15°,背盘平均冷却效率约降低0.003,当冷却系数为0.02～0.04时,预旋角每增加15°,背盘平均冷却效率降低0.016～0.050;冷却流体流入涡轮主流流道后,涡轮机效率受到冷却流体的影响而降低,当预旋角为60°时,冷却流体对涡轮机效率影响最小。     

某型船用燃气轮机涡轮叶片传热特性试验研究

本文对某型大功率船用燃气轮机涡轮气冷叶片进行了传热特性的试验研究,通过采用控制变量的方法进行模化试验,得到了不同工况点下的温比、流量比、燃气雷诺数下的涡轮叶片冷却效果。通过对试验结果的分析处理,进一步得到了涡轮叶片冷却效果随温比、流量比、燃气雷诺数的影响的变化规律呈指数关系式:θ′=0.363 K■K■Re■。试验结果表明,流量比对冷却的效果影响比较大,温比、燃气雷诺数对冷却效果影响较小;在一定温比、流量比情况下,燃气雷诺数的升高将导致冷却效果的提高。本试验建立该叶片的冷却效果试验关系式,为叶片冷却结构的优化和故障分析提供了试验依据。     

利用进气CFD分析改善活塞顶温度计算精度

采用试验和仿真分析的方法研究了发动机进气冷却作用对汽油机活塞顶温度分布影响.利用硬度塞测温法在发动机台架试验中测量了活塞顶各部位温度,分析比较了活塞顶进气门侧和排气门侧的温度差异.为了考虑冷空气进入气缸时对活塞顶不同部位冷却作用的不同,进行了发动机进气过程流体动力学计算(CFD),得到了进气过程中活塞顶不同部位的换热量,并将其用于修正活塞顶的热边界条件,在此基础上计算了活塞顶的温度分布,并和试验结果进行了对比分析.结果表明:进气冷却作用使得活塞顶进气门侧的温度明显低于排气门侧;利用进气过程CFD分析结果对活塞顶热边界条件进行修正后提高了计算精度,计算结果能够反映活塞顶进、排气门侧的温度差异.     

一次表面回热器进气结构对物流分配性能的影响

不合理的进气结构造成一次表面回热器(PSR)内部物流分配不均匀,影响同热器内部流体的流动和传热效果.本文提出了具有导流片的进气结构,并在尽可能地保证出口截面速度均匀分布的前提上,开展了不同进气结构对回热器芯体入口物流分配影响的研究.结果表明,在所研究的雷诺数范围内,改进后的进气结构中各通道出口截面速度的最大波动只有14...     

微型燃气轮机涡轮背盘冲击冷却特性研究

受可靠性和成本制约,微型燃气轮机冷却技术的发展和应用一直较为缓慢,已成为其进一步提升热效率的主要瓶颈。针对此问题,提出了一种简单可靠的径流涡轮新型冷却技术-背盘冲击冷却,使用气热耦合的方法对该冷却技术的冷却特性进行了仿真研究。结果表明:背盘冲击冷却可以大幅降低径流涡轮背盘的温度。当冷却气体流量为主流的2%时,冷却流体温度从473.0降到323.0 K,背盘平均温度降低了143.0～202.0 K;当冷却温度为323.0 K时,冷却气体消耗量从主流质量流量的1%增加到4%时,背盘平均温度降低150.0～252.0 K。冷却流体流入主流后会对其产生一定的影响,每增加1%的冷却流量,涡轮机效率下降约1%。     

Experimental investigation on propagation characteristics of liquid-fuel/preheated-air rotating detonation wave

The rotating detonation combustor can be applied to the turbine engine to develop into a new power device, and the liquid-fuel/air rotating denotation has important research significance for engine applications. In this research, the propagation characteristics of liquid-fuel/air rotating detonation wave were experimentally investigated. A hydrocarbon mixture—liquid gasoline was employed for the fuel, the oxidizer was high-temperature air preheated by a hydrogen-oxygen heater, and the rotating detonation wave was initiated via a hydrogen-oxygen pre-detonator. The effects of the equivalence ratio, ignition pressure, and air total temperature on the propagation characteristics of the liquid-fuel rotating detonation wave were analyzed. The liquid-fuel/air continuous rotating detonation wave can be successfully obtained with a single-wave mode, and the velocity and peak pressure of the rotating detonation waves increase as the equivalence ratio increases. As the detonation-wave pressures at the outlet of the pre-detonator increase, the establishment time of the rotating detonation wave gradually decreases, and the average establishment time is 4.01 ms. Stable rotating detonation waves are obtained with the air total temperature of 600–800 K, but the intensity of the detonation wave has a large deficit due to some instabilities.     

旋转对气冷涡轮内部流场影响的PIV测量

采用PIV测速技术分别对旋转和不旋转两种情况下的气冷涡轮内部流场进行实验测量,研究旋转对气冷涡轮内部流场的影响。同时改变吹风比(M=1.5,2),研究不同射流吹风比对涡轮流场的影响。实验结果表明,冷却孔射流下游附近存在明显的尾迹区域。旋转情况下涡轮内部流场中存在的离心力、哥氏力的作用使射流与主流的掺混流场结构改变。与静止涡轮叶栅流场相比,旋转对叶片压力面侧流场的影响明显大于吸力面。同时,吹风比增大使射流与主流掺混流场区域以及射流尾迹区的范围扩大。     

民用航空发动机气冷涡轮技术发展研究

本文简述了民用航空发动机的发展历程,低成本、高寿命涡轮是航空发动机的核心组件.指出提升涡轮进口温度是提高涡轮性能的有效措施,而采用气体冷却技术可以降低涡轮损耗,并进一步分析了气体冷却技术的种类和作用,为我国民用航空发动机气冷涡轮的研究和发展提供参考.     

Advances in effusive cooling techniques of gas turbines

Gas turbine combustion chambers and turbine blades require better cooling techniques to cope with the increase in operating temperatures with each new engine model. Current gas turbine inlet temperatures are approaching 2000 K. Transpiration-cooled components have proved an effective way to achieve high temperatures and erosion resistance for gas turbines operating in aggressive environments, though there is a shortage of durable and proven technical solutions. Effusion cooling, on the other hand, is a relatively simple and more reliable technique offering a continuous coverage of cooling air over the component’s hot surfaces. This paper presents a numerical model suitable to design the geometric features of effusive cooling systems of gas turbine hot components, and to evaluate their thermo-fluid-dynamic characteristics. The model has been developed specifically with the aim to show the potential advantages deriving from the adoption of the new Poroform^® technology. According to this technology the design of the distributions of the diameter and density of holes on the cooled surface allows complete freedom for the thermo-mechanical optimization of the cooled component, with a view to reducing the metal’s working temperature and achieving isothermal conditions for large blade areas.In this paper the diameter, density and spacing of the holes, the adiabatic film efficiency and the coolant air consumption of a first stage gas turbine effusion cooled blade are extensively discussed to highlight the system cooling capacity.The results of two cooling solutions for a first-stage gas turbine blade are presented, i.e. the thermo-fluid-dynamic optimized design and one possible manufacturing-oriented optimized design of the cooled component.     

燃气涡轮无气膜动叶设计流程及分析

为了进行涡轮动叶冷却结构设计,采用一套设计流程,完成了某型涡轮第一列动叶无气膜方案设计。结果表明:管网计算设计中,得出调整后冷却结构的第一腔流量为16.85 g/s,第二腔流量为40.78 g/s,前缘最大温度为1 169 K,低于材料许用温度,满足设计要求。三维导热中的最大温度相比管网计算得出的温度有所上升,通过分析,管网计算未能考虑极值温度,因此三维导热计算是有必要的。从给出的三个截面温度场可以看出,前缘位置存在一定高温区,但最大温度低于设计温度,温度场符合设计要求。     

Energetic and exergetic performance analyses of a combined heat and power plant with absorption inlet cooling and evaporative aftercooling

In this paper, exergy method is applied to analyze the gas turbine cycle cogeneration with inlet air cooling and evaporative aftercooling of the compressor discharge. The exergy destruction rate in each component of cogeneration is evaluated in detail. The effects of some main parameters on the exergy destruction and exergy efficiency of the cycle are investigated. The most significant exergy destruction rates in the cycle are in combustion chamber, heat recovery steam generator and regenerative heat exchanger. The overall pressure ratio and turbine inlet temperature have significant effect on exergy destruction in most of the components of cogeneration. The results obtained from the analysis show that inlet air cooling along with evaporative aftercooling has an obvious increase in the energy and exergy efficiency compared to the basic gas turbine cycle cogeneration. It is further shown that the first-law efficiency, power to heat ratio and exergy efficiency of the cogeneration cycle significantly vary with the change in overall pressure ratio and turbine inlet temperature but the change in process heat pressure shows small variation in these parameters.     

燃气轮机二次空气系统的设计要求与布置特点分析

燃气轮机内部的二次空气系统是用于透平高温部件的冷却与保护、密封及腔室增压,二次空气系统的合理设计对燃气轮机的热效率与运行安全性具有重要影响,本文结合某型燃气轮机的热力循环及透平结构特点分析了二次空气系统的功能、设计要求及系统布置特点。     

Effects of Various Geometric Features on the Performance of a 7:1 Pressure Ratio Deeply Scalloped and Split Radial Turbine in a Gas Turbine Engine

A 2 MW gas turbine engine has been developed for the distributed power market.This engine features a 7:1 pressure ratio radial inflow turbine.In this paper,influences of various geometry features are investigated including turbine tip and backface clearances.In addition to the clearances,the effects of the inducer deep scallop and exducer rounded trailing edge are investigated.Finally,geometric features associated with a split rotor(separate inducer and exducer)are studied.These geometry features are investigated numerically using CFD.Part of the numerical results is also compared to experimental data acquired during engine test to validate the CFD results.     

Influence of environmental factors on the corrosion-fatigue response of a nickel-based superalloy

Nickel disc corrosion is an important area within the gas turbine engine, with the potential to affect the lives of critical rotating parts. To understand the influence of corrosion on such components, it is essential to generate material data in a representative environment; hot corrosion in conjunction with cyclic loading. A comprehensive assessment of the behaviour of alloys U720Li and RR1000 in a laboratory-simulated environment has been undertaken to explore and replicate corrosion-fatigue features that have been identified in service. Key parameters such as salt loading (flux) and variations in mechanical stress cycle have been examined and have shown to modify the corrosion morphology and resulting fatigue life of the material.

This paper is part of a thematic issue on the 9th International Charles Parsons Turbine and Generator Conference. All papers have been revised and extended before publication in Materials Science and Technology.     

Performance enhancement of gas turbines by inlet air‐cooling in hot and humid climates

In this paper, a model to study the effect of inlet air‐cooling on gas turbines power and efficiency is developed for two different cooling techniques, direct mechanical refrigeration and an evaporative water spray cooler. Energy analysis is used to present the performance improvement in terms of power gain ratio and thermal efficiency change factors. Relationships are derived for an open gas turbine cycle with irreversible compression and expansion processes coupled to air‐cooling systems. The obtained results show that the power and efficiency improvements are functions of the ambient conditions and the gas turbine pressure ratio. The performance improvement is calculated for, ambient temperatures from 30 to 50°C, the whole range of humidity ratio (10–100%) and pressure ratio from 8 to 12. For direct mechanical refrigeration air‐cooling, the power improvement is associated with appreciable drop in the thermal efficiency. The maximum power gain can be obtained if the air temperature is reduced to its lowest limit that is the refrigerant evaporation temperature plus the evaporator design temperature difference. Water spray cooling process is sensitive to the ambient relative humidity and is suitable for dry air conditions. The power gain and efficiency enhancement are limited by the wet bulb temperature. The performance of spray evaporative cooler is presented in a dimensionless working graph. The daily performance of the cooling methods is examined for an ABB‐11D5 gas turbine operating under the hot humid conditions of Jeddah, Saudi Arabia. The results indicate that the direct mechanical refrigeration increased the daily power output by 6.77% versus 2.57% for the spray air‐cooling. Copyright © 2005 John Wiley & Sons, Ltd.