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編號
無錫太湖學(xué)院
畢業(yè)設(shè)計(jì)（論文）
相關(guān)資料
題目： 機(jī)械式擰瓶機(jī)的設(shè)計(jì)及工程分析
信機(jī) 系 機(jī)械工程及自動化專業(yè)
學(xué) 號： 0923116
學(xué)生姓名： 吳 建 軍
指導(dǎo)教師： 何雪明 （職稱：副教授 ）
（職稱： ）
2013年5月25日
目 錄
一、畢業(yè)設(shè)計(jì)（論文）開題報告
二、畢業(yè)設(shè)計(jì)（論文）外文資料翻譯及原文
三、學(xué)生“畢業(yè)論文（論文）計(jì)劃、進(jìn)度、檢查及落實(shí)表”
四、實(shí)習(xí)鑒定表
無錫太湖學(xué)院
畢業(yè)設(shè)計(jì)（論文）
開題報告
題目： 機(jī)械式擰瓶機(jī)的設(shè)計(jì)及工程分析
信機(jī) 系 機(jī)械工程及自動化 專業(yè)
學(xué) 號： 0923116
學(xué)生姓名： 吳 建 軍
指導(dǎo)教師： 何雪明 （職稱：副教授 ）
（職稱： ）
2012年11月20日
課題來源
工廠
科學(xué)依據(jù)
（1）課題科學(xué)意義
擰瓶機(jī)是自動灌裝生產(chǎn)線的主要設(shè)備之一，用于玻璃瓶或PET瓶的螺紋蓋封口。隨著社會的發(fā)展和人民生活水平的提高，人們對產(chǎn)品的包裝質(zhì)量的要求也越來越高。由于螺紋蓋具有封口快捷，開啟方便及開啟瓶后又可重新封好等優(yōu)點(diǎn)，使其在許多產(chǎn)品的包裝中應(yīng)用越來越廣泛，諸如飲料，酒類，調(diào)味料，化妝品及藥品等瓶包裝的封口就大量采用螺紋蓋封口。目前現(xiàn)有的國產(chǎn)同類機(jī)型的封蓋機(jī)的產(chǎn)量，速度和自動化程度都相對落后。為了適應(yīng)現(xiàn)代包裝機(jī)高速，高效和高可靠性生產(chǎn)的需要，研制了一種回轉(zhuǎn)式擰瓶機(jī)，該機(jī)采用多工位回轉(zhuǎn)式結(jié)構(gòu)，機(jī)電氣一體化，具有效率高，速度快，可靠性好和自動化程度高等優(yōu)點(diǎn)。
（2）擰瓶機(jī)的研究狀況及其發(fā)展前景
提高自動化程度是包裝機(jī)械發(fā)展重要的趨勢。產(chǎn)品和產(chǎn)量居世界之首的美國十分重視白裝機(jī)械與計(jì)算機(jī)緊密結(jié)合，實(shí)現(xiàn)機(jī)電一體化控制，將自動化操作程序、數(shù)據(jù)收集系統(tǒng)、自動檢驗(yàn)系統(tǒng)更多用于包裝機(jī)械之中。日本則長于微電子技術(shù)，用以開那個值包裝機(jī)械，有效地促進(jìn)了無人操作和自動化程度的提高。在計(jì)量、制造和技術(shù)性能等方面居于世界領(lǐng)先地位的德國也高度重視提高自動化程度。幾年前，德國包裝機(jī)械系統(tǒng)設(shè)計(jì)時，自動化技術(shù)在整個系統(tǒng)操作及運(yùn)行中還占30%，現(xiàn)在已占到50%以上。
研究內(nèi)容
① 了解數(shù)擰瓶機(jī)的工作原理，國內(nèi)外的研究發(fā)展現(xiàn)狀；
② 完成擰瓶機(jī)總體方案設(shè)計(jì)；
③ 完成零部件的選型計(jì)算、結(jié)構(gòu)強(qiáng)度校核；
④ 熟練掌握有關(guān)計(jì)算機(jī)繪圖軟件，并繪制裝配圖和零件圖紙，折合A0不少于2.5張；
⑤ 完成設(shè)計(jì)說明書的撰寫，并翻譯外文資料1篇。
擬采取的研究方法、技術(shù)路線、實(shí)驗(yàn)方案及可行性分析
（1）實(shí)驗(yàn)方案
實(shí)驗(yàn)通過通過UG軟件進(jìn)行動態(tài)模擬，分析材料是否在預(yù)定壽命內(nèi)失效，利用有限元分析方法，分析其數(shù)學(xué)求解原理，根據(jù)實(shí)際情況進(jìn)行離散化，進(jìn)而求解分析。仿真技術(shù)的運(yùn)用可以消除加工程序中的錯誤，有效地檢查出工件加工過程中可能存在的干涉，從而保證機(jī)床與人員的安全，提高加工效率，改善加工質(zhì)量，顯著降低生產(chǎn)成本。
（2）研究方法
通過參閱借來的參考資料和上網(wǎng)查閱相關(guān)信息，并對擰瓶機(jī)進(jìn)行實(shí)體觀察，認(rèn)真研究上體機(jī)結(jié)構(gòu)，了解擰瓶機(jī)工作原理，與指導(dǎo)老師交流來完成對擰瓶機(jī)上體結(jié)構(gòu)的畢業(yè)設(shè)計(jì)．
研究計(jì)劃及預(yù)期成果
研究計(jì)劃：
2012年11月10日-2013年1月25日：按照任務(wù)書要求查閱論文相關(guān)參考資料，填寫畢業(yè)設(shè)計(jì)開題報告書；完成一篇英文文獻(xiàn)翻譯
2013年1月26日-2月3日：進(jìn)行專業(yè)實(shí)訓(xùn)并對UG軟件學(xué)習(xí)使用；
2013年2月3日-2月17日：填寫畢業(yè)實(shí)習(xí)實(shí)訓(xùn)報告；
2013年2月17日-3月9日：對擰瓶機(jī)進(jìn)行整體結(jié)構(gòu)設(shè)計(jì)；
2013年3月10日-4月5日：開始擰瓶機(jī)主傳動系統(tǒng)設(shè)計(jì)；
2013年4月5日-5月5日：進(jìn)給傳動系統(tǒng)設(shè)計(jì)；
2013年5月6日-6月1日：基礎(chǔ)支撐件和輔助裝置設(shè)計(jì)；并完善畢業(yè)論文以及相關(guān)資料，為答辯做好充分的準(zhǔn)備。
預(yù)期成果：
（1） 達(dá)到預(yù)期的實(shí)驗(yàn)結(jié)論：按照計(jì)劃安排進(jìn)行本設(shè)計(jì)，完成的擰瓶機(jī)上體機(jī)基本可以實(shí)現(xiàn)預(yù)期功能,。熟練掌握有關(guān)計(jì)算機(jī)繪圖軟件，并繪制裝配圖和零件圖紙，折合A0不少于2.5張；完成設(shè)計(jì)說明書的撰寫，并翻譯外文資料1篇。
特色或創(chuàng)新之處
（1）主題明確，有針對性,穩(wěn)定, 易操作, 通用性強(qiáng)。
（2）使用簡易，功能完善。
（3）使生產(chǎn)率得到較大的提高，一改以前的單線生產(chǎn)
已具備的條件和尚需解決的問題
（1）技術(shù)條件：擰瓶機(jī)的總目標(biāo)已經(jīng)了解，同時明確了實(shí)現(xiàn)總目標(biāo)應(yīng)該采用的策略，對UG的能夠較熟練的使用。
（2）尚未解決的問題：①恰當(dāng)?shù)剡x擇機(jī)架材料，剛度、強(qiáng)度、穩(wěn)定性滿足要求的前提下獲得好的經(jīng)濟(jì)性。②對擰瓶機(jī)的結(jié)構(gòu)和整體設(shè)計(jì)還未確定
指導(dǎo)教師意見
指導(dǎo)教師簽名：
年 月 日
教研室（學(xué)科組、研究所）意見
教研室主任簽名：
年 月 日
系意見
主管領(lǐng)導(dǎo)簽名：
年 月 日
英文原文
Applications
4.1 Introduction
This chapter demonstrates the scope of the method developed for the three-dimensional analysis of a screw compressor. The CFD package used in this case was COMET developed by ICCM GmbH Hamburg, today a part of CD-Adapco. The analysis of the flow and performance characteristics of a number of types of screw machines is performed to demonstrate a variety of parameters used for grid generation and calculation.
The first example is concerned with a dry air screw compressor. A common compressor casing is used with two alternative pairs of rotors. The rotors have identical overall geometric properties but different lobe profiles. The application of the adaptation technique enables convenient grid generation for geometrically different rotors. The results obtained by three dimensional modelling are compared with those derived from a one-dimensional model, previously verified by comparison with experimental data..The relative advantages of each rotor profile are demonstrated.
The second example shows the application of three dimensional flow analysis to the simulation of an oil injected air compressor. The results, thus obtained, are compared with test results obtained by the authors from a compressor and test rig, designed and built at City University. They are presented in the form of both integral parameters and a p-indicator diagram. Calculations based on the assumptions of the laminar flow are compared to those of turbulent flow. The effect of grid size on the results is also considered and shown here.
The third example gives the analysis of an oil injected compressor in an ammonia refrigeration plant.This utilises the real fluid property subroutines in the process calculations and demonstrates the blow hole area and the leakage flow through the compressor clearances.
The fourth example presents two cases, one of a dry screw compressor to show the influence of thermal expansion of the rotor on screw compressor performance and one of a high pressure oil-flooded screw compressor to show the influence of high pressure loads upon the compressor performance.
4.2 Flow in a Dry Screw Compressor
Dry screw compressors are commonly used to produce pressurised air, free of any oil. A typical example of such a machine, similar in configuration to the compressor modelled, is shown in Figure 4-1. This is a single stage machine with 4 male and 6 female rotor lobes. The male and female rotor outer diameters are 142.380 mm and 135.820 mm respectively, while their centre lines are 108.4 mm apart. The rotor length to main diameter ratio l/d=1.77. Thus, the rotor length is 252.0 mm. The male rotor with wrap angle =248.40 is driven at a speed of 6000 rpm by an electric motor through a gearbox. The male and female rotors are synchronised through timing gears with the same ratio as that of the compressor rotor lobes i.e. 1.5. The female rotor speed is therefore 4000 rpm. The male rotor tip speed is then 44.7m/s, which is a relatively low value for a dry air compressor. The working chamber is sealed from its bearings by a combination of lip and labyrinth seals.
Each rotor is supported by one radial and one axial bearing, on the discharge end, and one radial bearing on the suction end of the compressor. The bearings are loaded by a high frequency force, which varies due to the pressure change within the working chamber. Both radial and axial forces, as well as the torque change with a frequency of 4 times the rotational speed. This corresponds to 400Hz and coincides with the number of working cycles that occur within the compressor per unit time.
Figure 4-1 Cross section of a dry screw compressor
The compressor takes in air from the atmosphere and discharges it to a receiver at a constant output pressure of 3 bar. Although the pressure rise is moderate, leakage through radial gaps of 150 m is substantial. In many studies and modelling ,procedures, volumetric losses are assumed to be a linear function of the cross sectional area and the square root of pressure difference, assuming that the interlobe clearance is kept more or less constant by the synchronising gears. The leakage through the clearances is then proportional to the clearance gap and the length of the leakage line. However, a large clearance gap is needed to prevent contact with the housing caused by rotor deformation due to the pressure and temperature changes within the working chamber. Hence, the only way to reduce leakage is to minimise the length of the sealing line. This can be achieved by careful design of the screw rotor profile. Although minimising,leakage is an important means of improving a screw compressor efficiency, it is not the only one. Another is to increase the flow area between the lobes and thereby increase the compressor flow capacity, thereby reducing the relative effect of leakage. Modern profile generation methods take these various effects into account by means of optimisation procedures which lead to enlargement of the male rotor interlobes and reduction in the female rotor lobes. The female rotor lobes are thereby strengthened and their deformation thus reduced.
To demonstrate the improvements possible from rotor profile optimisation, a three dimensional flow analysis has been carried out for two different rotor profiles within the same compressor casing, as shown in Figure 4-2. Both rotors are of the “N” type and rack generated.
Figure 4-2‘N’ Rotors, Case-1 upper, Case-2 lower
Case 1 is an older design, similar in shape to SRM “D” rotors. Its features imply that there is a large torque on the female rotor, the sealing line is relatively long and the female lobes are relatively weak.
Case 2, shown on the bottom of Figure 4-2, has rotors optimised for operating on dry air. The female rotor is stronger and the male rotor is weaker. This results in higher delivery, a relatively shorter sealing line and less torque on the female rotor. All these features help to improve screw compressor performance.
The results of these two analyses are presented in the form of velocity distributions in the planes defined by cross-sections A-A and B-B, shown in Figure 4-1.
In the case of this study, the effect of rotor profile changes on compressor integral performance parameters can be predicted fairly accurately with one-dimensional models, even if some of the detailed assumptions made in such analytical models are inaccurate. Hence the integral results obtained from the three-dimensional analysis are compared with those from a one-dimensional model.
4.2.1 Grid Generation for a Dry Screw Compressor
In Case-1, the rotors are mapped with 52 numerical cells along the interlobe on the male rotor and 36 cells along each interlobe on the female rotor in the circumferential direction. This gives 208 and 216 numerical cells respectively in the circumferential direction for the male and female rotors. A total of 6 cells in the radial direction and 97 cells in the axial direction is specified for both rotors. This arrangement results in a numerical mesh with 327090 cells for the entire machine. The cross section for the Case-1 rotors is shown in Figure 4-3. The female rotor is relatively thin and has a large radius on the lobe tip. Therefore, it is more easily mapped than in Case-2 where the tip radius is smaller, as shown in Figure 4-4.
Figure 4-3 Cross section through the numerical mesh for Case-1 rotors
The rotors in Case 2 are mapped with 60 cells along the male rotor lobe and 40 cells along the female lobe, which gives 240 cells along both rotors in the circumferential direction. In the radial direction, the rotors are mapped with 6 cells while 111 cells are selected for mapping along the rotor axis. Thus, the entire working chamber for this compressor has 406570 cells. In this case, different mesh sizes are applied and different criteria are chosen for the boundary adaptation of these rotors. The main adaptation criterion selected for the rotors is the local radius curvature with a grid point ratio of 0.3 to obtain the desired quality of distribution along the rotor boundaries. By this means, the more curved rotors are mapped with only a slight increase in the grid size to obtain a reasonable value of the grid aspect ratio. To obtain a similar grid aspect ratio without adaptation, 85 cells would have been required instead of 60 along one interlobe on the female rotor. This would give 510 cells in the circumferential direction on each of rotors. If the number of cells in the radial direction is also increased to be 8 instead of 6 but the number of cells along axis is kept constant, the entire grid would contain more then a million cells which would, in turn, result in a significantly longer calculation time and an increased requirement for computer memory.
Figure 4-4 Cross section through the numerical mesh for Case-2 rotors
4.2.2 Mathematical Model for a Dry Screw Compressor
The mathematical model used is based on the momentum, energy and mass conservation equations as given in Chapter 2. The equation for space law conservation is calculated in the model in order to obtain cell face velocities caused by the mesh movement. The system of equations is closed by Stoke’s, Fourier’s and Fick’s laws and the equation of state for an ideal gas. This defines all the properties needed for the solution of the governing equations.
4.2.3 Comparison of the Two Different Rotor Profiles
The results obtained for both Case 1 and Case 2 compressors are presented here. To establish the full range of working conditions and to obtain an increase of pressure from 1 to 3 bars between the compressor suction and discharge, 15 time steps were required. A further 25 time steps were then needed to complete the full compressor cycle. Each time step needed about 30 minutes running time on an 800 MHz AMD Athlon processor. The computer memory required was about 400 MB.
In Figure 4-5 the velocity vectors in the cross and axial sections are compared. The top diagram is given for Case-1 rotors and the bottom one for Case-2. As may be seen, the Case 2 rotors realised a smoother velocity distribution than the Case 1 rotors. This may have some advantage and could have increased the compressor adiabatic efficiency by reduction in flow drag losses. In both cases, recirculation within the entrapped working chamber occurs as consequence of the drag forces in the air as shown in the figure. On the other hand, different fluid flow patterns can be observed in the suction port. The velocities within the working chambers and the suction and discharge ports are kept relatively low while the flow through the clearance gaps changes rapidly and easily reaches sonic velocity.
Figure 4-5 Velocity field in the compressor cross section for Case1 and Case2 rotors
Figure 4-6 Velocity field in the compressor axial section for Case1 and Case2 rotors
These differences are confirmed in the view of the vertical compressor section through the female rotor axis, shown in Figure 4-6. In Case 2, lower velocities are achieved not only in the working chamber but also in the suction and discharge ports. In the suction port, this is significant because of the fluid recirculation which appears at the end of the port. This recirculation causes losses which cannot be recovered later in the compression process. Therefore, many compressors are designed with only an axial port instead of both, radial and axial ports. Such a situation reduces suction dynamic losses caused by recirculation but, on the other hand, increases the velocity in the suction chamber which in turn decreases efficiency. Some of these problems can be avoided only by the design of screw compressor rotors with larger lobes and a bigger swept volume and a shape which allows the suction process to be completed more easily. However, rotor profile design based on existing one-dimensional procedures neglects flow variations in the ports and hence is inferior for this purpose. In such cases, only a full three dimensional approach such as this, will be effective.
中文譯文
應(yīng)用
4.1簡介
本章介紹了對螺桿壓縮機(jī)的三維分析開發(fā)的方法的范圍。在這種情況下，采用由ICCM GmbH Hamburg開發(fā)的CFD軟件，現(xiàn)在是CD-Adapco的一部分。對一定數(shù)量的螺桿機(jī)器的類型的流程和性能特性的分析是用來展示用于柵格一代和演算的各種各樣的參量。
第一個例子是關(guān)于一個干螺桿空氣壓縮機(jī)。一個常見的壓縮機(jī)外殼是使用兩個可選雙轉(zhuǎn)子。轉(zhuǎn)子具有相同的整體幾何性質(zhì)但是有不同的葉剖面。適應(yīng)技術(shù)的應(yīng)用可以方便使網(wǎng)格生成幾何不同的轉(zhuǎn)子。三維模型得到的結(jié)果與從一個一維模型獲得的那些比較，以前被核實(shí)與實(shí)驗(yàn)數(shù)據(jù)相比。演示了每個轉(zhuǎn)子配置文件的相對優(yōu)勢。
第二個例子顯示了三維流動分析模擬注入油空氣壓縮機(jī)的應(yīng)用。如此得到的結(jié)果與從壓縮機(jī)的作者和試驗(yàn)臺，設(shè)計(jì)和建造城市大學(xué)通過以下方式獲得的測試結(jié)果進(jìn)行了比較。他們提出了兩個積分的形式參數(shù)和一個p-α示意圖。計(jì)算基于的假設(shè)是層流與湍流流動的那些進(jìn)行比較。網(wǎng)格尺寸對計(jì)算結(jié)果的影響也被認(rèn)為是在這里。
第三個例子給出了油中注入的制冷壓縮機(jī)的分析。這利用了現(xiàn)實(shí)的流體屬性的過程中計(jì)算的子程序，并演示吹孔區(qū)域和通過壓縮機(jī)的間隙泄漏流。
第四個例子呈現(xiàn)兩種情況，一是顯示的干式螺桿壓縮機(jī)的轉(zhuǎn)子的螺桿式壓縮機(jī)的性能，熱膨脹的影響和高壓油沒螺桿式壓縮機(jī)中的一個，以顯示的影響高壓負(fù)荷時壓縮機(jī)的性能。
4.2干燥螺絲壓縮機(jī)的流程
干燥螺絲壓縮機(jī)是常用的生產(chǎn)被加壓的空氣，不需要任何油。這樣機(jī)器的一個典型的例子，在配置與被塑造的壓縮機(jī)相似，在表4-1顯示。這是一個有4個陽性和6個陰性轉(zhuǎn)子葉單級機(jī)。陽性和陰性的轉(zhuǎn)子外直徑分別為142.380毫米和135.820毫米，而他們的中心線108.4毫米。轉(zhuǎn)子長度的主直徑比L / D = 1.77。因此，轉(zhuǎn)子長度252毫米。陽轉(zhuǎn)子與包角= 248.40在每分鐘6000轉(zhuǎn)的速度驅(qū)動，通過齒輪箱由一個電動馬達(dá)。陽性和陰性的轉(zhuǎn)子通過定時齒輪同步與壓縮機(jī)轉(zhuǎn)子裂片即1.5的相同比率。因此，陰性的轉(zhuǎn)子轉(zhuǎn)速為每分鐘4000轉(zhuǎn)。陽轉(zhuǎn)子葉尖速度然后44.7米/ s，這是相對低的值，為干燥的空氣壓縮機(jī)。工作腔密封從它的軸承，由唇，迷宮式密封的組合。每個轉(zhuǎn)子是由一個徑向和軸向軸承和一個徑向軸承在放電結(jié)束后吸入端的壓縮機(jī)。軸承是由一個高頻力加載，它會因在工作腔的壓力變化而變化。徑向和軸向的力，以及頻率的旋轉(zhuǎn)速度的4倍的轉(zhuǎn)矩變化。這對應(yīng)于400Hz和發(fā)生在壓縮機(jī)內(nèi)的每單位時間的工作周期數(shù)一致。
壓縮機(jī)以空氣從大氣排到一個接收器3個恒定的輸出壓力。雖然壓力上升是溫和的，經(jīng)過150徑向間隙泄漏是巨大的。在許多研究和建模過程中，容積損失被認(rèn)為是一個線性函數(shù)的橫截面積和壓差的平方根假設(shè)葉片間間隙保持或多或少不變的同步齒輪。然后，通過該間隙的泄漏間隙和泄漏管路的長度成比例。然而，一個大的間隙是必要的，以防止轉(zhuǎn)子變形，由于工作腔內(nèi)的壓力和溫度的變化所造成的與殼體接觸。因此，減少泄漏的唯一方法是將密封線長度。這可以通過仔細(xì)的螺桿轉(zhuǎn)子型線設(shè)計(jì)實(shí)現(xiàn)。盡管最小化泄漏是一個重要的手
圖4-1 干式螺桿壓縮機(jī)的截面
段,提高了螺桿壓縮機(jī)效率,卻不是唯一的一個。另一個是提高葉流之間的區(qū)域,從而提高壓氣機(jī)葉流量,從而減少了相對效應(yīng)的泄漏?，F(xiàn)代配置生成方法把這些不同的影響考慮通過優(yōu)化程序，導(dǎo)致擴(kuò)大陽轉(zhuǎn)子葉片和減少陰性轉(zhuǎn)子葉。陰性的轉(zhuǎn)子葉是加強(qiáng)及其變形從而降低。為了證明可能從轉(zhuǎn)子齒形優(yōu)化，改善已進(jìn)行了三維流場計(jì)算在兩個不同的轉(zhuǎn)子型線在同一個壓縮機(jī)殼體，如圖4-2所示。生成兩個轉(zhuǎn)子的“N ”型和機(jī)架。例1是一個比較老的設(shè)計(jì)，形狀類似SRM “D”的轉(zhuǎn)子。它的特點(diǎn)意味著陰轉(zhuǎn)子上，有一個大的轉(zhuǎn)矩，密封線是比較長的相對較弱陰性葉。顯示在圖4-2的底部，例2的轉(zhuǎn)子的優(yōu)化操作在干燥的空氣。陰性的轉(zhuǎn)子是強(qiáng)大而陽性的轉(zhuǎn)子是較弱的。這結(jié)果在較高的輸送，一個相對較短的密封線和扭矩少陰轉(zhuǎn)子上。所有這些特點(diǎn)有助于提高螺桿壓縮機(jī)的性能。
這兩個分析結(jié)果中的橫截面定義的平面A-A、B-B速度分布的形式出現(xiàn)，如圖4-1所示。
在本研究的情況下，轉(zhuǎn)子型線的變化對壓縮機(jī)的整體性能參數(shù)的影響可以相當(dāng)準(zhǔn)確地預(yù)測的一維模型，即使在這樣的分析模型作了詳細(xì)的假設(shè)是不正確的。因此，從三維分析得到的積分結(jié)果與一維模型的比較。
4.2.1用于干式螺桿壓縮機(jī)的網(wǎng)格生成。
在例1中，轉(zhuǎn)子被映射52個數(shù)值細(xì)胞沿葉片間的陽轉(zhuǎn)子和36個細(xì)胞沿著每個葉片間的陰轉(zhuǎn)子的圓周方向。這給出了分別在圓周方向上的208和216的數(shù)值的單元格的陽性和陰性的轉(zhuǎn)子。總共有6個細(xì)胞在徑向方向上，并在軸向方向上的97個細(xì)胞被指定為兩個轉(zhuǎn)子。這種安排導(dǎo)致整個機(jī)器327090細(xì)胞的數(shù)值嚙合。例1轉(zhuǎn)子的截面如圖4-3所示。陰性轉(zhuǎn)子比較薄，在葉頂大半徑上。因此，它是更容易比分析映射在尖端半徑越小，如圖4-4所示。
圖4–2 轉(zhuǎn)子'N ' ，例1上，例2下
圖4-3 通過案例1轉(zhuǎn)子截面數(shù)值網(wǎng)格
在例2中的轉(zhuǎn)子被映射60細(xì)胞沿凸轉(zhuǎn)子突齒40細(xì)胞沿陰性葉瓣這給沿兩個轉(zhuǎn)子在圓周方向上的240個細(xì)胞。在徑向方向上，轉(zhuǎn)子被映射到與6個細(xì)胞，111細(xì)胞被選擇為沿轉(zhuǎn)子軸的映射。因此，該壓縮機(jī)的整個工作腔有406570個細(xì)胞。在這種情況下，不同的大小被應(yīng)用，并且這些轉(zhuǎn)子的邊界適應(yīng)不同標(biāo)準(zhǔn)的選擇。轉(zhuǎn)子的主要適應(yīng)選擇的標(biāo)準(zhǔn)是與某個網(wǎng)格點(diǎn)分布，以獲得所需的質(zhì)量比為0.3，沿轉(zhuǎn)子的邊界的局部曲率半徑。通過這種方式,更多的彎曲轉(zhuǎn)子映射只有一個輕微增加網(wǎng)格大小來獲得一個合理的價值網(wǎng)格的長寬比。為了獲得一個類似85個細(xì)胞所需要的網(wǎng)格長寬比，而不是沿著一個葉片間的60陰轉(zhuǎn)子的。這將給510細(xì)胞在圓周方向上每個轉(zhuǎn)子。如果細(xì)胞的數(shù)量在徑向方向也增加到8代替6但數(shù)量的細(xì)胞沿軸不變，則整個網(wǎng)格將包含更多，然后一百萬細(xì)胞，從而反過來導(dǎo)致計(jì)算時間大大延長，增加計(jì)算機(jī)內(nèi)存要求。
通圖4 -4 過數(shù)值網(wǎng)格橫截面為例2轉(zhuǎn)子
4.2.2干式螺桿壓縮機(jī)的數(shù)學(xué)模型
所用的數(shù)學(xué)模型是基于在2章給出了動量，能量和質(zhì)量守恒方程。這個方程計(jì)算空間的保護(hù)模型是為了獲得細(xì)胞面速度引起的嚙合運(yùn)動。方程系統(tǒng)是封閉的斯托克城，傅立葉和菲克的法律和理想氣體狀態(tài)方程。這是定義控制方程解決方案所需的所有屬性。
4.2.3兩個不同的轉(zhuǎn)子的比較
獲得的結(jié)果對兩例1和例2壓縮機(jī)介紹如下。建立完整的范圍的工作條件和獲得增加壓力從1到3酒吧的壓縮機(jī)吸、排之間，15次步驟是必需的。一個進(jìn)一步的25次步驟然后需要完成完整的壓縮機(jī)循環(huán)。每個時間步需要大約30分鐘，運(yùn)行時間在一個800 MHz的AMD Athlon處理器。計(jì)算機(jī)內(nèi)存要求約400 MB。
圖4-5的速度矢量在十字架和軸向部分進(jìn)行比較。前圖給出案例1和轉(zhuǎn)子底部一個案例2。如可以看到的，在第2種情況的轉(zhuǎn)子實(shí)現(xiàn)更平滑的速度分布比第1種情況的轉(zhuǎn)子。可以增加壓縮機(jī)絕熱效率，減少流動阻力損失。在這兩種情況下，再循環(huán)在裹入工作腔發(fā)生的后果在空中拖曳力如圖。 另一方面，不同的流體流動模式可觀測到吸入口。工作腔和吸入閥和排出端口的速度范圍內(nèi)保持相對低的，而流過的間隙間隙的變化迅速，方便達(dá)到聲速。
圖4-5 壓縮機(jī)截面的例1和案例2轉(zhuǎn)子速度場
圖4-6 壓縮機(jī)軸向部分案例1和案例2轉(zhuǎn)子速度場
這些區(qū)別根據(jù)垂直的壓縮機(jī)部分被證實(shí) 通過陰性電動子軸，顯示在圖4-6上。在例2中，低速度達(dá)到不僅在工作室還在入口及出口的港口。在吸入口，這是很重要的,因?yàn)橐后w再循環(huán),結(jié)束時出現(xiàn)端口。這個循環(huán)造成損失是無法恢復(fù)后的壓縮過程。因此，許多壓縮機(jī)的設(shè)計(jì)只有一個軸向港口而不是兩個港口，徑向和軸向港口。這種情況下減少吸入動態(tài)而造成損失的再循環(huán)，但另一方面，增加的速度，吸入腔從而降低效率。這些問題中的某些問題，可避免僅由螺桿壓縮機(jī)的轉(zhuǎn)子的設(shè)計(jì)中具有較大的葉和更大的掃過容積的形狀，這使得更容易地完成吸入過程。然而，電動子根據(jù)現(xiàn)有的一維做法的外形設(shè)計(jì)忽略在口岸上的流程變化并且為此下等。在這種情況下,只有一個完整的三維方法如此，這將是有效的。