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%。     

径流式涡轮性能研究的进展

涡轮特性对涡轮增压器性能具有重要的影响,本文对涡轮特性的研究方法进行了简要的回顾.根据国内外学者对涡轮效率和涡轮流量特性的研究现状,总结了涡轮效率和流量特性的各种试验测量和数值计算方法,并简要分析了这些方法获得的涡轮性能参数的准确性,同时对这些方法各自的优缺点进行了对比.为涡轮增压器生产厂家获得涡轮特性提供参考.最后论文总结了涡轮性能研究方法的特点.     

径流式涡轮性能研究的进展

涡轮特性对涡轮增压器性能具有重要的影响,本文对涡轮特性的研究方法进行了简要的回顾。根据国内外学者对涡轮效率和涡轮流量特性的研究现状,总结了涡轮效率和流量特性的各种试验测量和数值计算方法,并简要分析了这些方法获得的涡轮性能参数的准确性,同时对这些方法各自的优缺点进行了对比。为涡轮增压器生产厂家获得涡轮特性提供参考。最后论文总结了涡轮性能研究方法的特点。     

传热对增压器径流涡轮叶片温度分布的影响

采用共轭传热计算方法,对某柴油发动机废气涡轮增压器径流涡轮流场进行了数值模拟,对比了叶轮在绝热和传热条件下温度分布的差别,研究了传热边界对叶轮温度分布的影响。结果表明,绝热条件下,叶片两侧的温度存在显著的温差,并且从叶轮进口到出口也有明显的温降;而传热条件下,相同叶高下的叶片表面温度分布近乎于一条直线,压力面和吸力面的温度几乎相同;在热平衡条件下,叶轮实体内的温度范围很小,不超过10 K,温度梯度较小表明由温差引起的热应力很小。     

双叉排孔脉动射流气膜冷却效率的实验与数值模拟研究

采用高精度红外热像仪测量了平板绝热气膜冷却效率,比较了双叉排孔和单排孔气膜冷却效率,分析了吹风比(M=0.65,1.0,1.5)和脉动频率(St=0,0.01,0.015,0.025)以及孔间作用对气膜冷却效率的影响,结合数值计算得到的瞬态流场和温度场分析了脉动射流气膜冷却下的流动传热机理。结果表明：在稳态射流工况下,单排孔的气膜冷却效率随着吹风比的增加而减小,双叉排孔的气膜冷却效率却随着吹风比的增加而增大;在脉动射流时,单排和双叉排孔的气膜冷却效率在低吹风比下低于稳态射流,在高吹风比下,脉动射流对气膜冷却效率的影响减小,且低频脉动射流气膜冷却效率略高于稳态射流。     

径流式涡轮增压器涡轮转子的摩擦焊

详细介绍了径流式涡轮增压器涡轮转子的摩擦焊工艺过程,并对摩擦焊后的试棒进行了拉伸、金相、硬度及冲击试验,试验结果证明了涡轮转子摩擦焊的可行性。     

燃气流温度场不均匀性的影响

2005年6月号报道，由燃气流温度场不均匀性引起的热应力和腐蚀增加将导致燃气轮机叶片的加速破坏。 燃气轮机内的燃气流温度场通常具有径向和周向的不均匀性，与高压涡轮前的平均值比较，温度还可以提高约60～80℃。当在燃气不包含腐蚀性杂质的良好条件下，燃气温度的提高反映在第一级导向器中产生的热应力大小上。     

气膜孔几何结构对涡轮叶片气膜冷却影响的研究进展

综述了近年来涡轮叶片气膜孔几何结构对气膜冷却特性影响的研究成果,介绍了影响气膜冷却效果的因素.总结了气膜孔结构对叶片前缘、叶片端壁以及对平板气膜冷却影响的研究现状.阐述了气膜孔结构对气膜冷却传热特性的影响.最后指出进一步优化气膜孔结构,综合考虑气膜孔尺寸、长度、间隔、形状以及相对透平叶片取向对气膜冷却的影响和新型气膜孔的研究.将是今后工作的重点.     

某MPC涡轮增压柴油机排温均匀性分析及优化设计

为提高某8缸直列模件式脉冲转换器(modular pulse converter, MPC)涡轮增压柴油机各缸排温均匀性,采用GT-Power仿真软件,搭建整机热力学仿真模型,对比额定工况下各缸的循环进气量、进气和排气道压力波、扫气压差,分析各缸扫气压差不均的影响因素。提出优化MPC歧管倾角、MPC总管直径、气门叠开角、发火顺序4项优化措施。仿真结果表明：优化MPC总管直径、气门叠开角、发火顺序可显著提高各缸排温均匀性,MPC歧管倾角对各缸排温均匀性影响较小。对不同MPC歧管倾角、不同MPC总管直径的柴油机进行台架试验验证。试验结果表明,歧管倾角对各缸排温均匀性影响甚微;将MPC总管直径缩减至原直径的57%,排温标准差由43℃降至30℃,排温均匀性得到显著提高。     

气膜孔形状对涡轮叶片气膜冷却影响的研究进展

气膜冷却是航空发动机叶片上采用的冷却方式之一,气膜孔结构对冷却效率影响非常显著。通过对不同形状孔射流气膜冷却回顾,指出了圆柱孔射流冷却的有害涡流动结构。论述了几何结构和气动参数对气膜冷却特性的影响,提出了一种高效气膜冷却孔结构——双出口气膜孔。利用商业软件对双出口射流的冷却效率进行了数值模拟。结果表明,双出口孔射流时,形成的涡结构有利于冷气贴附在壁面。最后给出了圆柱孔和双出口孔射流冷却效率对比结果,无论在平板上还是在叶片前缘,双出口孔射流冷却效率都明显高于圆柱孔射流冷却效率。     

冷却空气量对涡轮冷却性能影响综述

涡轮冷却技术被广泛应用于航空发动机及燃气轮机涡轮研发中,冷却空气的引气量成为影响整机效率的重要因素之一。本文基于现代燃气轮机及航空发动机涡轮叶片采用外部冷却与内部冷却结合的复合冷却的技术发展背景,综述了国内外在冷却空气量对涡轮叶片冷却性能影响方面的研究进展,分析并总结了冷却空气量对气膜冷却、交错肋冷却以及对综合冷却效率的影响规律,并对未来的研究方向给出了一定的建议。分析表明：对气膜孔形状的探索是未来气膜冷却技术研究的重点;交错肋研究主要处于定性研究阶段,对定量研究方法的探索是目前的发展趋势;对综合冷却效率的研究还处于起步阶段,未来可以从外部冷却和内部冷却之间的相互作用关系方面对综合冷却效率开展进一步的研究。     

大型燃气轮机透平冷却空气量估算

大型燃气轮机透平冷却空气量一般难以直接获得。本文从燃机总体物质与能量平衡的角度,结合透平一级静叶的冷却模型,给出了一种估算大型燃气轮机冷却空气量的方法,并对GE公司系列燃气轮机和西门子公司V94．3燃气轮机冷却空气量进行了估算。结果表明采用本文的方法估算的燃气轮机透平冷却空气量是合理的。     

Conjugate heat transfer investigation on the cooling performance of air cooled turbine blade with thermal barrier coating

A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera. Besides, conjugate heat transfer numerical simulation is performed to obtain cooling efficiency distribution on both blade substrate surface and coating surface for comparison. The effect of thermal barrier coating on the overall cooling performance for blades is compared under varied mass flow rate of coolant, and spatial difference is also discussed. Results indicate that the cooling efficiency in the leading edge and trailing edge areas of the blade is the lowest. The cooling performance is not only influenced by the internal cooling structures layout inside the blade but also by the flow condition of the mainstream in the external cascade path. Thermal barrier effects of the coating vary at different regions of the blade surface, where higher internal cooling performance exists, more effective the thermal barrier will be, which means the thermal protection effect of coatings is remarkable in these regions. At the designed mass flow ratio condition, the cooling efficiency on the pressure side varies by 0.13 for the coating surface and substrate surface, while this value is 0.09 on the suction side.     

Effect of various inlet air cooling methods on gas turbine performance

Turbine air inlet cooling is one of many available commercial methods to improve the efficiency of an existing gas turbine. The method has various configurations which could be utilized for almost all installed gas turbines. This paper presents a comparison between two commons and one novel inlet air cooling method using turbo-expanders to improve performance of a gas turbine located at the Khangiran refinery in Iran. These methods have been applied to one of the refinery gas turbines located at the Khangiran refinery in Iran. Two common air cooling methods use evaporative media or a mechanical chiller. The idea behind the novel method is to utilize the potential cooling and power capacity of the refinery natural gas pressure drop station by replacing throttling valves with a turbo-expander. The study is part of a comprehensive program with the goal of enhancing gas turbine performance at the Khangiran gas refinery. Based on the results, it is found that using turbo-expanders is the most economically feasible option and so is recommended to be utilized for improving gas turbine performance at the Khangiran refinery.     

西门子公司V94.3燃气轮机冷却空气信息推测

作为建立燃用低热值合成气的燃气轮机变工况模型的一个关键步骤，对西门子V94.3燃气轮机冷却空气参数及其分配进行了研究，试图从公开发表的燃气轮机功率、压比、排气温度、三亿透平初温等数据中推测出冷却空气量的分配规律。计算和推测所得到的冷却空气参数和分配规律与燃机净功率以及ISO温度基本吻合。     

Effect of a hybrid jet impingement/micro-channel cooling device on the performance of densely packed PV cells under high concentration

This paper studies in deep the performance of a new hybrid jet impingement/micro-channel cooling scheme for densely packed PV cells under high concentration. The device combines a slot jet impingement with a non-uniform distribution of micro-channels. The Net PV output of the concentrator system, defined as the PV output less the pumping power, and its temperature uniformity are analyzed. The hybrid cooling scheme offers a minimum thermal resistance coefficient of 2.18 × 10⁻⁵ K m²/W with a pressure drop lower than in micro-channel devices. This characteristic involves that the Net PV Output of the PV receiver is higher when cooled by the hybrid design than when cooled by the micro-channel one. The chance to modify, at the design stage, the internal geometry of the hybrid cooling scheme allows improving the temperature uniformity of the PV receiver through the adequate distribution of the local heat removal capacity.     

Investigation on cooling effectiveness and aerodynamic loss of a turbine cascade with film cooling

This paper describes the numerical study on film cooling effectiveness and aerodynamic loss due to coolant and main stream mixing for a turbine guide vane. The effects of blowing ratio, mainstream Mach number, surface curvature on the cooling effectiveness and mixing loss were studied and discussed. The numerical results show that the distributions of film cooling effectiveness on the suction surface and pressure surface at the same blowing ratio (BR) are different due to local surface curvature and pressure gradient. The aerodynamic loss features for film holes on the pressure surface are also different from film holes on the suction surface.     

回热燃气轮机余热利用进气冷却的研究

本文研究了利用余热制冷进气冷却的回热燃气轮机系统,并对该系统性能进行了模拟计算,得到了压比、流量比等参数对系统性能的影响规律。并通过与常规回热循环比较,指出利用余热制冷来进气冷却的方式能使系统效率提高11%,是提高燃气轮机系统性能的有效途径之一。     

Performance characteristics and modelling of a micro gas turbine for their integration with thermally activated cooling technologies

We have developed a simple model of a micro gas turbine system operating at high ambient temperatures and characterized its performance with a view to integrating this system with thermally activated cooling technologies. To develop and validate this model, we used experimental data from the micro gas turbine test facility of the CREVER research centre. The microturbine components were modelled and the thermodynamic properties of air and combustion gases were estimated using a commercial process simulator. Important information such as net output power, microturbine fuel consumption and exhaust gas mass flow rate can be obtained with the empirical correlations we have developed in this study. This information can be useful for design exhaust gas fired absorption chillers. Copyright © 2006 John Wiley & Sons, Ltd.