【摘要】：離心壓縮機(jī)廣泛應(yīng)用于冶金、化工、氣體工業(yè)、機(jī)械等各個(gè)領(lǐng)域,因此在國(guó)民經(jīng)濟(jì)發(fā)展中占有非常重要的位置。擴(kuò)壓器作為離心壓縮機(jī)中的核心靜止部件,對(duì)提高壓縮機(jī)級(jí)壓比和效率,改善最佳工況點(diǎn)有著十分顯著作用,因此研究不同出口安裝角葉片擴(kuò)壓器的流動(dòng)特性對(duì)離心壓縮機(jī)的運(yùn)行有著重要的意義。本文以某一臺(tái)多級(jí)離心壓縮機(jī)首級(jí)作為研究對(duì)象,對(duì)帶不同出口安裝角擴(kuò)壓器的離心壓縮機(jī)級(jí)進(jìn)行數(shù)值模擬,得出不同出口安裝角情況下離心縮機(jī)單級(jí)的性能曲線,分析各擴(kuò)壓器不同葉高截面的流線和靜壓分布、不同等半徑截面的總壓得出擴(kuò)壓器出口安裝角對(duì)擴(kuò)壓器內(nèi)部流動(dòng)的影響以及損失機(jī)理,同時(shí)采用壓力恢復(fù)系數(shù)對(duì)比分析不同工況下不同擴(kuò)壓器的擴(kuò)壓效果;首次提出擴(kuò)壓器內(nèi)的速度畸變指數(shù)概念進(jìn)而分析各擴(kuò)壓器流道內(nèi)氣流的不均勻性,同時(shí)確定發(fā)生分離損失時(shí)的速度畸變指數(shù)臨界值;對(duì)比分析擴(kuò)壓器內(nèi)具有代表性位置的跨盤蓋(軸向)絕對(duì)馬赫數(shù)的分布。結(jié)果表明:隨著擴(kuò)壓器出口安裝角增大時(shí),級(jí)性能曲線向大流量區(qū)移動(dòng),雖最高效率和壓比先升高后降低,但對(duì)它們的提升并不明顯且運(yùn)行的最大工況變化不大;不同出口角度葉片擴(kuò)壓器的擴(kuò)壓效果由在不同工況下的流動(dòng)特性決定;當(dāng)擴(kuò)壓器進(jìn)口安裝角不變時(shí),小流量時(shí)隨著擴(kuò)壓器出口安裝角增大,出口安裝角大的擴(kuò)壓器最先出現(xiàn)分離并形成渦流區(qū),渦流區(qū)從葉腹出口處發(fā)展到葉腹前緣,葉腹出現(xiàn)的旋渦對(duì)總壓損失影響較小;大流量時(shí),不同出口角度擴(kuò)壓器葉背形成分離區(qū)且旋渦位置不同,渦流區(qū)從葉背前緣發(fā)展到葉背出口處,葉背出現(xiàn)的旋渦對(duì)總壓損失影響較大;同一擴(kuò)壓器在不同葉高截面的靜壓和流動(dòng)情況也存在差異,葉片擴(kuò)壓器蓋側(cè)流動(dòng)情況比盤側(cè)好;速度畸變指數(shù)低于0.8時(shí),擴(kuò)壓器發(fā)生分離損失;擴(kuò)壓器的出口安裝角對(duì)擴(kuò)壓器入口處流動(dòng)無(wú)明顯影響。
[Abstract]:Centrifugal compressor is widely used in metallurgy, chemical industry, gas industry, machinery and other fields, so it occupies a very important position in the development of national economy. As the core static component of centrifugal compressor, diffuser plays a significant role in improving the compressor stage pressure ratio and efficiency, and improving the optimum working point. Therefore, it is of great significance to study the flow characteristics of blade diffuser with different outlet angles for the operation of centrifugal compressor. Taking the first stage of a multistage centrifugal compressor as the research object, the centrifugal compressor stage with different outlet angle diffuser is numerically simulated, and the single stage performance curve of centrifugal shrinkage machine is obtained under different outlet installation angles. By analyzing the flow line and static pressure distribution of different blade height sections of diffusers, and the total pressure of different radius sections, the influence of outlet mounting angle on the internal flow of diffusers and the loss mechanism are obtained. At the same time, the pressure recovery coefficient is used to analyze the diffuser's diffuser effect under different working conditions. The concept of velocity distortion index in diffuser is put forward for the first time, and the inhomogeneity of airflow in each diffuser channel is analyzed, and the critical value of velocity distortion exponent when separation loss occurs is determined. The distribution of absolute Mach number of cross-disc cover (axial) in representative position of diffuser is compared and analyzed. The results show that with the increase of the outlet mounting angle of diffuser, the stage performance curve moves to the large flow zone, although the maximum efficiency and the pressure ratio first increase and then decrease, but the lifting of them is not obvious and the maximum operating condition change is not obvious. The diffuser effect of blade diffuser with different outlet angle is determined by the flow characteristics under different working conditions. When the installation angle of diffuser inlet is constant, when the installation angle of diffuser outlet increases with small flow rate, the diffuser with large outlet installation angle first appears separation and forms eddy current zone, the eddy current zone develops from the outlet of ventral lobe to the leading edge of ventral lobe. The vortex in the ventral lobe had little effect on the total pressure loss. When the flow rate is large, the separation zone is formed at the back of the diffuser with different outlet angles and the vortex position is different. The vortex zone develops from the front edge of the back of the leaf to the outlet of the back of the leaf, and the vortex in the back of the leaf has a great influence on the total pressure loss. The static pressure and flow of the same diffuser at different blade height sections are different, the flow situation of the cover side of the blade diffuser is better than that of the disk side, and when the velocity distortion index is lower than 0.8, the diffuser loses separately. The outlet mounting angle of diffuser has no obvious effect on the inlet flow of diffuser.
【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TH452

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