涡轮活塞发动机排气系统流动控制研究

发布时间：2018-04-12 17:53

本文选题：涡轮活塞发动机 + 引气　；参考：《清华大学》2015年硕士论文

【摘要】：涡轮活塞发动机是柴油机与燃气轮机联合循环工作的发动机,结合了柴油机的低油耗和燃气轮机的高功率密度优点,是高功率密度发动机发展的重要趋势之一。涡轮活塞发动机在柴油机与燃气轮机联合模式下工作时,需要将柴油机的排气引入燃气轮机的涡轮系统中,以回收柴油机的排气能量,提高联合循环发动机的燃油经济性。引气直接影响着燃气轮机的燃烧室出口压力和柴油机的排气背压,对燃气轮机和柴油机的性能均有重要影响。论文针对某涡轮活塞发动机中燃气轮机的两级涡轮系统建立了计算流体力学基础仿真模型,对仿真模型进行了网格无关性分析和校核。利用所建立的模型,首先研究了燃气涡轮前和两级涡轮间引气两类方案。通过在涡轮机匣上“开槽”作为引气口,研究了不同位置、不同角度引气对两级涡轮性能的影响。研究发现两级涡轮级间引气会大幅降低燃气涡轮的性能,不适用于涡轮活塞发动机。对于燃气涡轮前引气方案,研究了引气口的轴向位置、周向分布均匀性、引气进口面积、引气角度和引气流量等多种因素对两级涡轮系统性能的影响规律。在上述研究的基础上,设计了两类共四种引气装置,通过仿真对带有各种引气装置的复合涡轮系统方案进行了对比分析。研究发现燃气涡轮的性能受引气的影响比动力涡轮更大;在同类型引气装置方案对比中,燃气涡轮和动力涡轮的性能存在相互制约的关系;采用蜗壳形式的引气装置可降低引气进口压力。通过方案对比分析指出,采用正旋流蜗壳引气装置具有最好的性能。论文还分析了引气装置及复合涡轮系统内部的流动情况。结果表明引气装置对涡轮主流道内气流的周向均匀性影响较大,蜗壳类引气装置仅对较高叶高处的主流道气体流动有较大影响,而常规引气装置甚至可以影响到靠近轮毂附近的气体流动。具有30°出口导流结构的引气装置对气流的导向作用十分明显,可消除引气装置出口附近的分离流动,但会增加引气装置的进口压力。采用不同的引气装置,燃气涡轮导叶前缘的驻点位置不同,动力涡轮转子叶片入口叶尖附近均存在较大的正攻角,导致一定的冲角损失,需要通过转子叶型优化予以改善。
[Abstract]:Turbine piston engine is a kind of diesel engine combined with gas turbine. It combines the advantages of low fuel consumption of diesel engine and high power density of gas turbine. It is one of the important trends in the development of high power density engine.When the turbine piston engine works in the combined mode of diesel engine and gas turbine, it is necessary to introduce the exhaust gas of the engine into the turbine system of the gas turbine in order to recover the exhaust energy of the diesel engine and improve the fuel economy of the combined cycle engine.The exhaust gas directly affects the outlet pressure of the combustion chamber of the gas turbine and the exhaust back pressure of the diesel engine, and has an important effect on the performance of both the gas turbine and the diesel engine.In this paper, a basic computational fluid dynamics simulation model is established for the two-stage turbine system of a gas turbine in a turbo piston engine. The mesh independence analysis and verification of the simulation model are carried out.Based on the established model, two kinds of air entrainment schemes between gas turbine front and two stage turbine are studied.The effect of different positions and angles on the performance of the two stage turbine was studied by using "slot" on the turbine casing as the air entrainer.It is found that the performance of gas turbine can be greatly reduced by two stage air entrainment, which is not suitable for turbine piston engine.The influences of axial position, uniform circumferential distribution, inlet area, entrainment angle and flow rate on the performance of two-stage turbine are studied.On the basis of the above research, two kinds of four kinds of air entrapment devices are designed, and the schemes of composite turbine system with various air entrainers are compared and analyzed by simulation.It is found that the performance of gas turbine is more affected by air entrainment than that of power turbine, and that the performance of gas turbine and power turbine are restricted by each other in the scheme comparison of the same type of gas entrainer.The inlet pressure of air entraining can be reduced by using volute air entraining device.Through comparison and analysis of the schemes, it is pointed out that the use of positive swirl volute air entrainment has the best performance.The flow inside the air entrainer and the complex turbine system is also analyzed.The results show that the air entrainment has a great influence on the flow uniformity of the flow in the turbine mainstream channel, and the volute type air entraining device has a great influence on the flow of the gas in the mainstream channel at the higher blade height.Conventional air entrainers can even affect the flow of gas near the hub.The air entraining device with 30 掳outlet diversion structure has a very obvious guiding effect on the air flow, which can eliminate the separation flow near the outlet of the air entraining device, but it will increase the inlet pressure of the air entraining device.With different entrainment devices, the position of the front edge of the guide blade of the gas turbine is different, and there is a large positive angle of attack near the inlet blade tip of the power turbine rotor blade, which leads to a certain incidence loss, which needs to be improved through the optimization of the rotor blade shape.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK401

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