本文關鍵詞： 渦輪增壓 離心壓氣機 有葉擴壓器 穩(wěn)定性 畸變　出處：《清華大學》2014年碩士論文　論文類型：學位論文

【摘要】：內(nèi)燃機節(jié)能減排的需求及日益嚴格的排放法規(guī)要求渦輪增壓離心壓氣機具有寬廣的穩(wěn)定工作范圍。渦輪增壓離心壓氣機的流動穩(wěn)定性成為發(fā)展渦輪增壓技術的主要瓶頸之一。 渦輪增壓離心壓氣機具有周向非對稱的蝸殼結(jié)構(gòu)，導致離心壓氣機的周向流場結(jié)構(gòu)在非設計工況下不均勻；傳統(tǒng)流動控制措施認為離心壓氣機為軸對稱結(jié)構(gòu)，忽略了此流場結(jié)構(gòu)非對稱性。清華大學基于渦輪增壓離心壓氣機固有的非對稱流場特征，提出了“非對稱流動控制”思想。擴壓器對渦輪增壓離心壓氣機穩(wěn)定性具有重要影響，本論文基于“非對稱流動控制”思想，探索非對稱有葉擴壓器擴穩(wěn)新方法，，以期實現(xiàn)離心壓氣機穩(wěn)定工作范圍的大幅度拓寬。 為方便改變出口畸變的參數(shù)，定量分析擴壓器出口壓力畸變對離心壓氣機性能影響，本文用周向非均勻壓力分布作為出口邊界條件代替蝸殼建立了畸變模型，并證明了畸變模型可以用來分析蝸殼產(chǎn)生的畸變對離心壓氣機性能的影響。基于畸變模型，通過給定出口壓力畸變不同的幅值研究了壓力畸變在離心壓氣機中的傳播規(guī)律及壓力畸變幅值對離心壓氣機壓比、效率和穩(wěn)定工作范圍的影響。結(jié)果表明出口壓力畸變會降低離心壓氣機的壓比、效率和穩(wěn)定工作范圍，隨著畸變幅值的增加，離心壓氣機性能降低增加。擴壓器出口壓力畸變能夠傳播到上游的擴壓器和葉輪，導致部分流道率先發(fā)生失速，進而引發(fā)整個離心壓氣機喘振，隨著出口壓力畸變振幅的增加，率先發(fā)生失速時的流量也會增加，導致離心壓氣機穩(wěn)定工作范圍降低，從而揭示了局部失速誘發(fā)系統(tǒng)提前喘振的物理機理。 基于蝸殼導致的壓力畸變對離心壓氣機性能影響機理，突破目前國際上離心壓氣機的有葉擴壓器均為對稱分布的傳統(tǒng)，首次提出并發(fā)展了“非對稱有葉擴壓器”流動控制新方法：通過分析蝸殼引起的擴壓器出口的壓力畸變，判斷率先發(fā)生失速的區(qū)域，通過有葉擴壓器葉片安裝角或稠度非對稱布置，抑制此區(qū)域的流動分離，從而提高有葉擴壓器離心壓氣機的穩(wěn)定工作范圍。根據(jù)此方法設計了非對稱有葉擴壓器改型方案，并進行了仿真和試驗驗證。仿真結(jié)果表明：非對稱有葉擴壓器葉片安裝角或稠度分布能夠抑制蝸殼畸變導致的有葉擴壓器局部失速，從而拓寬有葉擴壓器離心壓氣機的穩(wěn)定工作范圍。試驗結(jié)果表明：轉(zhuǎn)速為90%時，離心壓氣機的穩(wěn)定工作范圍由25.4%提高到33.1%。
[Abstract]:The demand for energy saving and emission reduction of internal combustion engines and the increasingly stringent emission regulations require a wide range of stable operation for turbocharged centrifugal compressors. The flow stability of turbocharged centrifugal compressors has become one of the main bottlenecks in the development of turbocharging technology. The circumferential asymmetric volute structure of the turbocharged centrifugal compressor leads to the non-uniformity of the circumferential flow field of the centrifugal compressor under non-design conditions, and the conventional flow control measures consider the centrifugal compressor to be an axisymmetric structure. The asymmetry of the flow field structure is ignored. Based on the inherent asymmetric flow field characteristics of the turbocharged centrifugal compressor, Tsinghua University puts forward the idea of "asymmetric flow control". The diffuser has an important effect on the stability of the turbocharged centrifugal compressor. Based on the idea of "asymmetric flow control", this paper explores a new method for stabilizing the asymmetric blade diffuser in order to widen the working range of centrifugal compressor by a large margin. In order to change the parameters of outlet distortion and quantitatively analyze the influence of diffuser outlet pressure distortion on the performance of centrifugal compressor, a distortion model is established in this paper, in which the circumferential non-uniform pressure distribution is used as the outlet boundary condition instead of the volute case. It is proved that the distortion model can be used to analyze the effect of the distortion produced by the volute on the performance of centrifugal compressor. The propagation law of pressure distortion in centrifugal compressor and the pressure ratio of pressure distortion to centrifugal compressor are studied by giving different amplitudes of outlet pressure distortion. The results show that the pressure ratio of centrifugal compressor, the efficiency and the working range of centrifugal compressor will be decreased with the increase of distortion amplitude. The pressure distortion at the outlet of the diffuser can propagate to the diffuser and impeller upstream, which leads to the first stall in some of the flow channels, which leads to the surge of the whole centrifugal compressor, and with the increase of the amplitude of the pressure distortion at the outlet, The flow rate will also increase when the first stall occurs, which leads to the decrease of the stable working range of the centrifugal compressor, thus revealing the physical mechanism of the local stall induced system surge ahead of time. Based on the influence mechanism of pressure distortion caused by volute on the performance of centrifugal compressor, this paper breaks through the tradition that the vaned diffuser of centrifugal compressor in the world is symmetrical distributed at present. For the first time, a new flow control method for "asymmetric vaned diffuser" is proposed and developed. By analyzing the pressure distortion at the outlet of the diffuser caused by the volute, the region where the stall occurs first is judged. The flow separation in this area is restrained by asymmetric arrangement of the blade mounting angle or consistency of the blade diffuser, thus increasing the stable working range of the centrifugal compressor of the blade diffuser. According to this method, the modification scheme of the asymmetric blade diffuser is designed. The simulation results show that the distribution of blade mounting angle or consistency of asymmetric blade diffuser can restrain the local stall of blade diffuser caused by volute distortion. The experimental results show that the stable working range of centrifugal compressor increases from 25.4% to 33.1 when the rotating speed is 90.
【學位授予單位】：清華大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TH452

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本文編號：1495836