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چیکده
مقدمه
(DINE)تست تجربی و برنامه آزمون
اندازه گیری حالت پایدار
پذیرش نتایج کامل وجزئی
نتایج پژوهش نابرابر
نتایج جریان ناپایدار
نتیجه گیری

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استفاده از توربین شعاعی دوورودی به احتمال زیاد به عنوان یک روش معمول در توربوشارژرهای خودروها با موتور دیزلی خواهد بود.در این مورد،توربین تحت پذیرش نا برابری در خر ورودی ودر جریان ضربان دار است.بنابراین دانش رفتار توربین در چنین شرایطی یک نیاز اساسی برای توسعه محاسبات برای بهبودراندمان موتور است. با این حال تحقیقات بسیارکمی در توربین های دو ورودی وعملکردشان انجام شده است که تحت این شرایط کارمی کند.این آزمون اختصاصی داده شده است که توسعه تست ها ی مختلف قطعات وورودی وخروجی سیستم موتور احتراق در جریان مداوم وشرایط ضربان دار باشد.با اشاره خاص به توربوشارژربه آن اجازه می دهد تا تست توربین های تک ورودی ودوورودی،بیش از طیف گسترده ای از بارها وسرعت باشد.نتایج یک تحقیق تجربی بر روی توربین گرت در این مقاله ارائه شده ومورد بحث قرار گرفت.
پایداری وعملکرد ضربان دار جریان توربین با اشاره به شرایط پذیرش کانل وناقص ونابرابر اندازه گیری شد.نفوذپالس فازی با یک اختلاف نیز مورد لررسی قرار گرفت.نتایح تجربی لا اشاره به برخی از رفتارهای آنها در زیر ارائه شده است.
1.کارایی توربین دو ورودی کمتر از توربین تک ورودی است.این اثر توسط محققان دیگر نیز مشاهده شده وممکن است در اثر تلفات انرژی در مخلوط کردن دو جریان موجود بوجود آمده باشد.
2.دو ورودی به طور قابل توجهی از لحاظ شرعت جریان و بهره وری ویژگی هایی دارند.آزمون پذیرش کامل وجزئی نشان می دهد که ظرفیت مکش و کارایی،همیشه برای حالت دو ورودی بالاتر می باشد.ایت تفتوت رفتار ممکن است با توجه به هندسه روتورواستاتور توضیح داده شود که نشان میدهد،عدم تقارن ظاهری وجود دارد.

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INTRODUCTION Pulse turbocharging technique is widely used nowadays, especially in the field of vehicle diesel engines. The main goal is to take full advantage of the high pressure and temperature which exist in the cylinderwhen the exhaust valve (or port) opens, even at the expense of creating highly unsteady flow thrOUgh the turbine. This system requires small-bore and small-volume manifolds, which give rise to sensible interferences between cylinders joined into ODe pipe. It is generally recognized that the best efficiencies afe achieved by grouping three cylinders in ODe manifold, since in this case the quiescent period between pressure pulses is kept to a minimum while unfavorable interferences between cylinders afe avoided (Watson and Janota, 1982). This technique allows a better scavenge process and an increased volumetric efficiency, especially at low engine speed and torque. T o separate pressure pulses in each manifold the resulting configuration of the exhaust system requires the use of a multiple-entry turbocharger turbine. Vaneless radiai flow turbines far vehicle applications afe usually fitted with twoentry casings, divided either meridionally (twin-entry type ) or circumferentially. Meridionally divided casings afe often used, since they allow far higher efficiencies aver a wider operating range (Pischinger and Wunsche, 1977). The flow characteristics (pressure, temperature, speed) at both turbine entries change continuously during the engine cycle. As a consequence, the turbocharger turbine instantaneously operates in partial or unequal admission conditions. Moreover, depending on the number of engine cylinders connected to each manifold and on the firing order, pressure pulses at the turbine entries afe not likely to be in phase. The knowledge of turbine performance under these operating conditions is very useful to improve turbocharger matching and to achieve a better understanding of the exhaust system behavior. Since in the open literature little detailed performance data afe available far radiaI twin-entry turbines (Watson and Janota, 1982; Dale and Watson, 1986), theoretical and experimental investigations afe required in this field. Testing a twin-entry turbocharger turbine needs a suitable experimental facility that allows independent contrai of admission conditions for each entry, both in steady and in pulsating flow. This paper describes the results of a broad experimental investigation on an automotive twinentry turbocharger turbine developed on~e facility of the Department of Energetic Engineering of the University of Genoa (DINE). Arrangement of the turbine feeding line on the test facility. Fig. 1 mometer. Turbine power can be evaluated on the basis of measurements on the compressor side of the turbocharger. Controlling the compressor supply pressure and, therefore, its power absorption allows to extend considerably measured turbine operating range without the complexity and costs of a dedicated high-speed dynamometer. In the present investigation it was possible to cover a load range equivalent to blade-speed ratios u/cs from 0.55 to 1.00. The main supply line of the test facility was dedicated to the turbine. The experimental arrangement allows tests on two-entry turbines with Culi, partial or unequal admission, both in steady and pulsating flow conditions. The main characteristics of unsteady flow simulating the engine exhaust can be controlled independently for each turbine entry and the phase between the pressure pulses can be easily modified in steps of l/IO of the pulse periodo A schematic of the turbine feeding line is shown in Fig. 1. The pressure governor and the flow rate measuring station EXPERIMENTAL FACILlTY AND TEST PROGRAM The DINE test facility was initially developed to run tests on turbochargers, and then modified to allow measurements on different devices including complete intake and exhaust systems of automotive engines. The facility layout was fully described in previous papers (Capobianco and Gambarotta, 1992). The main source of compressed air is three electrically-driven screw compressors, with a maximum delivery of about 0.65 kg/s at a maximum pressure of 8 bar.

نوشته دانلود ترجمه مقاله کارایی توربین موتور شارژکننده توربین دو ورودی در خودرو – نشریه ASME اولین بار در ترجمه فا پدیدار شد.

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چکیده
مقدمه
مدلسازی CFD
شبیه سازی ثابت
جریان در حلقه
جریان در روتور
شبیه سازی ناپایدار
تجزیه و تحلیل طیفی
شبیه سازی جریان ضربانی
نتیجه گیری

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شبيه سازي جريان پايدار و گذرا از طريق اجزاي توربين شعاعي با دو ورودي ، بينش خوبي نسبت  با ساختارهاي پيچيده جريان  هوا را بوجود مي اورد. در مرحله اول، نفوذ زبانه توسط فاشر كم از سيال ورودي  به روتور با زاويه  600   به تصوير كشيده شده است. در مرحله دوم منطقه بين فضا توسط تلفات ، با توجه به اختلاط مشخص بين جريان كفي و توپي در تقسيم جريان وجود دارد. تجزيه و تحليل طيفي نوسانات فشار در دوره تناوبي فضاي زمان براي مورد شبيه سازي گذرا، هردو حالبت جريان ضربان دار و غير ضربان دار در ورودي نشان داده شده است. همچنين حالت  فضا و سرعت چرخشي و دامنه مشخص اين ناپايداري ها تعيين مي شود. پره و تعاملات روتور به وضوح از طريق شرايط روتور و زبانه و اثرات بالقوه  ارائه شده است. در مورد تجزيه و تحليل جريان ضربان دار مي توان گفت كه تسلط بر فركانس پالس زماني بوده و تقسيم عددي بر مضرب BPF بوده و تعامل  بين زبان ه وپره به نظر مي رسد كه غالبتر است. براي پذيرش نابرابري مختلف، تجزيه و تحليل طيفي نوسانات  فشار در درون فضا ثبت شده كه به نظر مي رسد همان رفتار از سيگنال هاي فضايي بدست امده از طريق ارتباط ثابت n مي باشد.  

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Introduction Radial inflow turbines are widely used in the turbocharging of diesel engines owing to their capacity to absorb the residual energy from exhaust gases. For a single-entry volute, the flow rate of exhaust gas is low at lower engine speeds, and therefore the exhaust pressure at the gathering point of an exhaust manifold is low, resulting in a low boost pressure. By using a twin-entry radial inflow turbines there is a better recovery of energy from the pulsating exhaust gases. Despite they become extensively used in turbocharging, they only benefited from few studies as compared to single-entry radial turbines. Pischiger and Wunsche1 studied twin-entry turbines under steady conditions and showed that unequal inlet conditions have a significant effect on the turbine performance. Also, Dale and Watson2 indicated significant effects of partial and unequal admissions on both the swallowing capacity and efficiency of a twin-entry turbine, and showed that the maximum efficiency does not necessarily occur under equal admission, and these conclusions were also supported by the experiments of Capobianco and Gambarotta.3 Yeo and Baines4,5 extended the study of Dale and Watson using laser two-focus velocimetry techniques to examine the flow inside a turbine, and showed that for different operating points and equal admission the flow incidence is close to 30. Doppler velocimetry measurements by Karamanis et al.6 under steady and pulsating conditions revealed complex flow patterns at both inlet and exit and the unsteady performance have a substantial deviation from the performance and flow characteristics of steady state. Experimental results of two versions of a mixed-flow turbine were obtained by Hakeem et al.,7 which revealed that in the steady case, the use of a volute with a larger swallowing capacity may result in a higher isentropic efficiency at lower speeds and higher velocity ratios, whereas the unsteady case indicated that the instantaneous performance and flow characteristics deviate substantially from their steady-state values. In the last two decades, the flow simulations in the support of turbomachinery design and development have grown to a considerable extent, as a consequence of the rapid evolution of computing power. By using CFX code, Simpson et al.8,9 showed that the vaned stators present a higher total pressure losses compared to equivalent vaneless volutes which exhibit higher levels of flow uniformity at rotor entry, yielding an improved turbine efficiency, which was also confirmed by the experimental investigations due Spence et al.10 The performance of a turbocharger’s twin-entry radial turbine was investigated analytically and experimentally by Aghaali and Hajilouy-Benisi11 and Hajilouy-Benisi et al.12 under steady state, considering the full and partial admission. The results revealed that when the ratio of the shroud and hub side mass flows is very high, the efficiency is lower than that of the full admission. Hellstro¨m and Fuchs,13 in their first report presented numerical analyses for a vaneless turbine coupled to an IC engine operating at 1500 r/min and 3000 r/min, concluded that for the second speed, the inlet flow angle varies from approximately from 67 to 25 which is more favourable than for the first speed where this angle was from 85 to 60 accompanied with a drop in the peak shaft power about 4%. In their two other reports,14,15 a variety of non-pulsatile inlet boundary conditions including uniform flow and several combinations of turbulence with swirl and streamwise vortices were tested. As results, the undisturbed inlet profile gave the highest time-averaged power output while the performance of pulsating flow deviates subsequently from the steady one, as also confirmed later by Costall et al.,16 Copeland et al.17 Romagnoli et al.18 compared between the steady performance of double-entry and twin-entry turbocharger turbines, and showed that in the case of a twin radial turbine, the interaction between entries is significant and causes the flow capacity to be larger than that would be obtained by halving the mass flow in a full admission in contrary to the double-entry turbine. The interaction phenomena between the rotor and the stationary components is considered to have a strong influence on the flow of a radial turbine and a better understanding is required in order to improve its design.

نوشته دانلود ترجمه مقاله آنالیز جریان ثابت و ناپایدار در توربین شعاعی موتور شارژ کننده توربین اولین بار در ترجمه فا پدیدار شد.

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چکیده
۱ مقدمه
۲ تئوری پایه
الف معادلات حاکم
ب خواص گاز واقعی
ج عملکرد
د مدل سازی اغتشاشی
هـ استراتژی راه حل
۳ راه اندازی آزمایش
۴ راه اندازی مدل
الف مدل سازی
ب مطالعه شبکه
ج دیواره نزدیک
د شرایط مرزی
۵ نتایج
۶ نتیجه گیری

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در اين مقاله طراحي و ارزيابي عملكرد يك توربين با هندسه متغير دوورودي نامتقارن مورد بحث قرار گرفت. اين طراحي توربين براي بهبود عمليات EGR موتور و افزايش استخراج انرژي از اگزوز در موتورهاي چندسيلندر بزرگ است. طراحي با تجزيه و تحليل ميانگين خط اوليه به منظور رفع پارامترهاي عمومي هندسي توربين آغاز شده، سپس طراحي كامل توربين توسط مدلسازي سه بعدي CFD مورد ارزيابي قرار گرفت. به عنوان يك نتيجه از اين فرايند، توربين به صورت نا متقارن با دو ورودي با مقادير 160-200، 10% نسبت نرخ EGR را داشته و پره هندسه متغير دزر توربين تك ورودي استخراج جريان EGR را داشته است.
شبيه سازي براي تعدادي از سرعت هاي توربين مختلف در 100% و 50% سرعتها، مقادير SPR 0.5 و 1.5 و زاويه پره -100 و 00 و +100 را نشان مي دهد. نتايج شبيه سازي نشان داد كه نقطه اوج بهره وري تحت SPR مي تواند رخ دهد كه با كارايي 78% تا 100% توربين بوده و نرخ EGR،20% مي باشد. و بهره وري مشاهده شده در 50% سرعت با اوج بازده به مقدار 76% بوده است. همچنين پيكربندي پره مي تواند براي نرخ هاي EGR مختلف امكان بهينه سازي شرايط جريان در ورودي به توربين را نشان دهد كه ممكن است براي حفظ شرايط پذيرش برابر بوده و از اين رو كارايي توربين بهينه براي طيف گسترده اي از EGR خواهد بود.

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INTRODUCTION AND PROBLEM DEFINITION Due to the increasingly stringent emission regulations and demand for high fuel economy, turbocharger is inherently one of the most promising enabling technologies towards achieving engine design for low emissions and fuel consumption. Turbochargers are not only expected to provide efficient exhausts energy recovery, but they are also used in order to support engine operation by controlling engine back-pressure for enhanced EGR rate. In large multi-cylinder engines, single-entry VGTs are normally used due to their ability to support EGR and instantaneous boost pressure response. However, the disadvantage of singleentry VGTs is that they do not enable to maximize energy extraction out of the exhausts pulses (pulse turbocharging) since there is no pulse separation within the turbine volute (as in multiple-entry turbines). Hence, aim of this research, is that of combining the advantages of exhausts pulse energy extraction and variable geometry turbocharging in one single turbine design. Pulse turbocharging (i.e. conserving pulse energy until the rotor entry) is a wellknown technique to utilise the maximum energy of the exhausts. In order to avoid exhausts pulse interference, these are isolated with multiple-entry turbines. Two types of multiple-entry turbines are currently available in the market: meridionally divided “twin-entry” turbines and circumferentially divided “double-entry” turbines (Figure 1). The twin-entry turbine is divided meridionally and each incoming flow is fed into the entire rotor circumference. In contrast, double-entry turbine feeding area is divided circumferentially and incoming flows are guided with radially In order to merge the requirements of imbalanced mass flow and the pulse turbocharging advantage, asymmetric vaneless twin-entry turbine design has been proposed by Müller et al. (2) and lately optimized by Brinkert et al. (3). Their work showed that it is possible to achieve remarkable EGR-rates in some regions of the engine map, even though the average exhausts back-pressure is lower than the charge air pressure thus limiting the operations for this design. A different approach than that provided by (2) and (3) is proposed in the current paper, with the design of an asymmetric variable geometry double-entry turbine. The reasons for the selection of this turbine configuration are explained as follows. In order to extract exhaust gases and recirculate it into the intake side, exhaust manifold pressure has to be higher than the intake manifold pressure. Therefore a VGT is necessary to increase exhaust manifold pressure corresponding with widely changeable transient operation. Besides supporting EGR control strategies by changing exhaust manifold pressure, VGT also offers the additional advantage of varying the inlet area to the turbine wheel thus maximizing exhausts flow energy extraction at different engine operating conditions. The choice of asymmetric (a) (b) Outer limb Inner limb Entry 2 Entry 1 322 double-entry geometry in place of a twin-entry one can be explained by considering that adopting symmetrically divided multiple-entry turbines in EGR engines, would lead to an imbalance of mass flow caused by EGR extraction from one side of the exhausts manifold. This flow imbalance can hardly be controlled in twin-entry turbines since the flow leaving the two entries mix together before entering the wheel. This is not the case in double-entry turbine configuration since the flows from the two entries are completely isolated and introduced into the turbine wheel separately, so that the flow controllability is believed to be more effective than in twin-entry turbine. A typical arrangement for the asymmetric variable geometry double-entry turbine is given in Figure 2. More details are provided in the next paragraph.

نوشته دانلود ترجمه مقاله بهینه سازی نامتقارن توربین توربوشارژ با عملکرد پالس EGR اولین بار در ترجمه فا پدیدار شد.