本文選題：離心葉輪 + 氣動性能　； 參考：《天津大學》2012年碩士論文

【摘要】：近年來，離心壓縮機不斷向高壓比、高效率發(fā)展。葉輪氣動設計的發(fā)展直接關系著葉輪機械的發(fā)展水平,是葉輪機械氣動力學領域研究的重點。半開式離心葉輪因其強度高、極限圓周速度大、單級壓比高等優(yōu)點得到廣泛應用。 本文采用反命題設計方法，以某離心壓縮機級內(nèi)閉式離心葉輪為研究對象，以提高其效率、壓比和擴大穩(wěn)定工作范圍為目標，通過控制葉片載荷分布改變?nèi)~片三維結構、改變?nèi)~片前緣位置，探討和研究了離心葉輪優(yōu)化設計方法；進而對經(jīng)典葉輪在葉頂處等值切削形成不同間隙值的半開式葉輪進行數(shù)值計算，探究葉頂間隙對半開式離心葉輪氣動性能和流場的作用機理。 在對原始葉輪進行數(shù)值模擬、明確內(nèi)部流動特性和氣動性能基礎上，采用三種措施進行反命題優(yōu)化設計：1）以原始葉輪子午型線為基礎，通過控制葉片載荷分布改變?nèi)~片三維結構，，進而優(yōu)化葉輪氣動性能；2）確定最佳載荷分布形式，改變?nèi)~輪出口寬度，以消除出口氣流分離為目的優(yōu)化葉輪氣動性能；3）確立適當?shù)娜~片前緣位置，改善流動分離現(xiàn)象并擴大葉輪工況范圍。通過數(shù)值模擬對設計結果進行氣動性能分析，確立葉輪葉片的最佳結構設計參數(shù)。優(yōu)化后的葉輪性能明顯提高，高效區(qū)域范圍顯著擴大。 葉頂間隙值是影響半開式葉輪氣動性能的關鍵因素。研究表明，葉頂間隙導致葉輪頂隙損失增大，性能降低，但間隙值與流動損失的變化成非線性關系；恰當?shù)娜~頂載荷分布可有效抑制頂隙內(nèi)泄漏量；頂隙渦流與主流之間的相互作用主要體現(xiàn)在葉輪的中下游流道，引起當?shù)仫@著地熵增，不同運行工況形成的葉片前緣間隙泄漏渦旋結構與特征迥異；間隙泄漏流動本身引起的流動損失較小，間隙渦流與主氣流相互摻混引起的損失是葉輪效率降低的主要原因。 本文研究結果為具有復雜三維結構的離心葉輪的設計提供最優(yōu)氣動與結構匹配參數(shù)和優(yōu)化指導，為高效閉式離心葉輪向大流量半開式應用領域拓展探究流動機理。
[Abstract]:In recent years, centrifugal compressor to high pressure ratio, high efficiency development. The development of impeller aerodynamic design is directly related to the development level of impeller machinery. Semi-open centrifugal impeller is widely used because of its high strength, high limit circumference velocity and high single stage pressure ratio. In this paper, the inverse proposition design method is used to study the inner closed centrifugal impeller of a centrifugal compressor stage. With the aim of improving its efficiency, pressure ratio and expanding the stable working range, the three dimensional structure of the blade is changed by controlling the load distribution of the blade. The optimum design method of centrifugal impeller is discussed and studied by changing the position of blade leading edge, and then the numerical calculation of semi-open impeller with different clearance values formed by equivalent cutting of classical impeller at the top of the blade is carried out. The action mechanism of tip clearance on aerodynamic performance and flow field of semi-open centrifugal impeller was investigated. On the basis of numerical simulation of the original impeller and definite internal flow characteristics and aerodynamic performance, three measures are adopted to optimize the inverse proposition design: 1) based on the original impeller meridian profile. By controlling the blade load distribution to change the three dimensional structure of the blade and then optimize the aerodynamic performance of the impeller, the optimal load distribution form is determined, and the outlet width of the impeller is changed. In order to eliminate the outlet flow separation, the aerodynamic performance of the impeller is optimized. (3) the proper vane leading position is established, the flow separation phenomenon is improved and the working range of the impeller is enlarged. The aerodynamic performance of the impeller blade was analyzed by numerical simulation, and the optimum design parameters of impeller blade were established. After optimization, the performance of impeller is improved obviously, and the area of high efficiency is greatly expanded. The tip clearance is the key factor to affect the aerodynamic performance of semi-open impeller. The results show that the tip clearance increases and the performance decreases, but the change of the gap value is nonlinear to the flow loss, and the proper top load distribution can effectively restrain the leakage in the top gap. The interaction between the top gap vortex and the main stream is mainly reflected in the middle and lower flow channel of the impeller, which results in a significant increase in local entropy, and the leakage vortex structure and characteristics of the leading clearance of the blade formed under different operating conditions are very different. The flow loss caused by interstitial leakage flow itself is relatively small, and the loss caused by the mixing of clearance vortex and main airflow is the main reason for the decrease of impeller efficiency. The results of this paper provide optimal aerodynamic and structural matching parameters and guidance for the design of centrifugal impeller with complex three-dimensional structure, and expand the flow mechanism of high efficiency closed centrifugal impeller to large flow semi-open application field.
【學位授予單位】：天津大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TH452

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