某型微型离心压气机流场分析及其改型研究

发布时间：2019-04-26 01:50

【摘要】：随着现代航空工业的不断发展,微小型飞行器在现代军事、民用领域得到了广泛应用,在不久的将来,微小型飞行器将在各个领域担任越来越重要的角色。微小尺寸的发动机是微型飞行器的心脏,其中压气机部件是发动机极其重要的部件之一,因此,设计一款小尺寸、高压比、高效率的高性能压气机是目前研究的重点之一。在微尺寸发动机中,由于压气机的尺寸限制,对高精度制造难度较大,离心式压气机更为适宜,在制造难度上较低,此外,离心压气机单级压比要远高于轴流式压气机。由于离心压气机的流场较轴流式压气机更为复杂,对于高压比、高效率的压气机,需要通过很好的控制内部流动,同时考虑激波损失与附面层流动分离等,设计难度极高,设计高性能的离心压气机有很大的研究价值。本文主要将应用于16da N推力的一种微型涡喷发动机中的离心压气机实施改型设计,要求改型后压气机能够达到20da N推力涡喷发动机的使用要求,改型后压气机满足给定设计指标的各项性能要求。根据原型涡喷发动机的离心压气机的结构,测量出压气机的叶型轮廓和通流通道的几何数据,利用三维建模软件UG建立压气机的实体模型,最后利用三维流体计算软件CFX对原型离心压气机进行流场计算,得到设计点工况下原型离心压气机的内部流场数据及总体性能参数,与试验数值进行对比,重点讨论了造成内部流动严重损失及使流场趋于复杂紊乱流动的原因,其中探讨了尾迹、二次流、分离流的影响因素。接着,针对原型压气机的几何外形尺寸,重新设计压气机部件,针对改型性能要求,改善压气机流动方向的大折转角度造成的恶劣分离流动,在不改变进出口径向尺寸的条件下,开展高压比、高转速、高效率的叶轮改型设计;另外,由于原型扩压器结构造成的严重的损失,流动控制效果较差,重新设计了扩压器叶片形式及布置方式,重新进行流场计算分析,将改型与原型进行对比分析。最终设计结果表明,改型设计后离心压气机滞止等熵效率达到74.36%,流量达到0.4236kg/s,总压比为4.136,较原型分别提高了12.67%、9.17%和18.17%,均达到了设计指标。该型号离心压气机设计转速达到125000r/min,转速较高,在叶尖位置产生超音区域,在离心力和激波增压共同作用下,提升了离心压气机的增压能力。另外,改型后离心压气机出口参数更为均匀,叶顶处出口气流角大幅减小,从整体来看,出口气流角减小,均匀性提高。
[Abstract]:With the development of modern aviation industry, micro-aircraft has been widely used in modern military and civil fields. In the near future, micro-aircraft will play a more and more important role in various fields. Micro-sized engine is the heart of micro-aircraft, in which compressor component is one of the most important parts of the engine. Therefore, the design of a small size, high-pressure ratio, high-efficiency compressor is one of the most important research points at present. In micro-sized engine, because of the size limitation of compressor, it is difficult to manufacture high-precision compressor, centrifugal compressor is more suitable and less difficult to manufacture. In addition, the single-stage pressure ratio of centrifugal compressor is much higher than that of axial-flow compressor. Because the flow field of centrifugal compressor is more complicated than that of axial compressor, for high pressure ratio and high efficiency compressor, it is very difficult to design the compressor which needs to control the internal flow well and consider the separation of shock wave loss and boundary layer flow at the same time, it is very difficult to design the compressor with high pressure ratio and high efficiency. The design of high performance centrifugal compressor has great research value. In this paper, the centrifugal compressor used in a micro turbojet engine with 16da-N thrust is designed. It is required that the modified compressor can meet the requirements of the 20da-N thrust turbojet engine. The modified compressor meets the performance requirements of the given design index. According to the structure of the centrifugal compressor of the prototype turbojet engine, the geometric data of the blade profile and the passage of the compressor are measured, and the solid model of the compressor is established by using the 3D modeling software UG. Finally, the three-dimensional fluid calculation software CFX is used to calculate the flow field of the prototype centrifugal compressor, and the internal flow field data and the overall performance parameters of the prototype centrifugal compressor under the design point condition are obtained, which are compared with the experimental data. In this paper, the causes of serious loss of internal flow and the complicated and disturbed flow field are discussed, and the influencing factors of wake, secondary flow and separated flow are discussed. Then, according to the geometric dimensions of the prototype compressor, the compressor components are redesigned to improve the bad separation flow caused by the large rotation angle in the flow direction of the compressor according to the performance requirements of the modified compressor. The design of high pressure ratio, high speed and high efficiency impeller is carried out without changing the radial dimension of inlet and outlet. In addition, due to the serious loss caused by the structure of the prototype diffuser and the poor effect of flow control, the blade form and arrangement of the diffuser are redesigned, the flow field is calculated and analyzed again, and the contrast analysis is carried out between the retrofit and the prototype. The final design results show that the static Isentropic efficiency of centrifugal compressor is 74.36%, the flow rate is 0.4236 kg / kg, and the total pressure ratio is 4.136, which is 12.67%, 9.17% and 18.17% higher than the prototype, respectively. All of them have reached the design target. The centrifugal compressor has a design speed of 125 000 r / min and a high speed. The supersonic region is produced at the tip position of the centrifugal compressor. Under the combined action of centrifugal force and shock wave pressurization, the turbocharging capacity of the centrifugal compressor is improved. In addition, the outlet parameters of the modified centrifugal compressor are more uniform, and the outlet gas flow angle at the top of the blade decreases greatly. As a whole, the outlet gas flow angle decreases and the uniformity of the centrifugal compressor increases.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：V233

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