Дисертації з теми "Seals of compressors"

Oil ring seals are one major source of instability in high pressure centrifugal compressors. This thesis presents a method for analysis of an improved seal concept that has been used in very high pressure designs (900 PSI). The improved design uses a combination of ring seals and tilting pad bearing elements. The stable tilting pad is used to center the heavily grooved seal element. The eight stiffness and damping coeflicients which represent the hydrodynamic forces between the journal and the seal assembly are computed by an automated computer code for evaluation of both the standard ring seal and the tilting pad elements. Both synchronous and nonsynchronous steady state characteristics have been included in the analysis. The nonsynchronous whirl of the rotor and its effects on the stiffness and damping coefiicients of a 5 tilting pad seal have been given in the form of design curves. The effect of pad inertia which has been neglected in many bearing analysis codes has been incorporated in this seal analysis, and allowed the determination of the exact cross coupling stiffness and damping coefficients.

Master of Science

Seals are considered one of the important flow elements of a turbomachinery device. Traditional labyrinth seals have proven their performance functionality by reducing leakage rates. Significant improvements on labyrinth seal functionality were obtained through altering the design geometry of labyrinth seals to prevent contamination across a seal and maintaining small leakage flowrates. This results in a windback seal that has only one tooth which continuously winds around the shaft like a screw thread. These seals are used in gas compressors to isolate the gas face seal from bearing oil. A purge gas is passed through the seal into the bearing housing. The helical design allows the seal to clear itself of any oil contamination. Windback seal performance is controlled through changing the seal geometry. A 2D graphical design tool for calculating the total and cavity leakage flowrates for windback seals is introduced. The effectiveness of the Fluent CFD (Computational Fluid Dynamics) commercial code to accurately predict the leakage rate for windback seals was evaluated. The objective is to determine if CFD simulations can be used along with a few experimental tests to study windback seals of this design with air as the working fluid. Comparison of measurement and predictions for a windback seal using the κ-ε turbulence model with enhanced wall treatment functions show predictions and measurements comparing very well with a maximum difference of 5% for leakage rate. Similarly, the leakage rate of the tested smooth seal compares favorably with two dimensional CFD predictions, with a difference of 2%-11% and 8%-15% using laminar and κ-ε turbulent flow models, respectively. The variation of leakage with shaft speed and pressure ratio across the seals is accurately predicted by the CFD simulations. Increasing the rotor speed to 15000 rpm increases the measured leakage flowrate for the windback seal by 2% at high differential pressure and 4.5% at low differential pressure, and decreases it by 10 % for the smooth seal. The effects of seal clearance, tooth pitch, cavity depth and the tooth number of starts on leakage flowrate, velocity and pressure distributions were studied numerically for three differential pressures and four rotor speeds.

Основной отличительной особенностью работы центробежных компрессоров (ЦК) в составе дожимных компрессорных станций является работа при переменном (снижающемся) давлении газа на входе и необходимости обеспечения постоянного значения давления на выходе. Это требует применения компрессоров, обеспечивающих высокие значения отношений давлений. Работа таких компрессоров характеризуется небольшим объемным расходом компримируемого газа, по сравнению с компрессорами линейных компрессорных станций, что пропорционально увеличивает влияние протечек в межступенчатых уплотнениях на эффективность работы ЦК. В связи с этим вопросы обеспечения минимальных внутренних перетечек в компрессоре являются достаточно актуальными.

This thesis presents numerical predictions for the leakage and direct stiffness coefficients of pocket damper seals. Modifications made to earlier flow-prediction models are discussed. Leakage and static pressure measurements on straight-through and diverging configurations of eight-bladed and twelve-bladed seals were used for code validation and for calculation of seal discharge coefficients. Higher than expected leakage rates were measured in the case of the twelve-bladed seal, while the leakage rates for the eight-bladed seals were predicted reasonably accurately. Results are presented for shake tests conducted on the seals at pressures of up to 1000 Psi (6.90 MPa). Test variables included pressure drop across the seals and rotor speed. The experimentally obtained stiffness coefficients are compared to results of a rotordynamic damper seal code, which uses the corrected mass flow-rate calculation method. Results show that the code under-predicts the magnitude of the seal's stiffness for most test cases. However, general trends in the frequency dependency of the direct stiffness are more accurately predicted. The expectation of high values of negative stiffness in diverging seals is confirmed by the results, but the frequency at which the sign of the stiffness becomes positive is considerably lower than is predicted. In addition to presenting high-pressure test data, this thesis also attempts to provide some insight into how seal parameters can be modified to obtain desired changes in seal stiffness.

This master’s thesis deals with theme of turbocharger seals. The aims of a thesis are to compare a turbocharger seals used in PBS Turbo turbochargers and to describe a testing of a seals. Principle of turbocharging and types of turbocharger are described in fist part. Next point of the thesis is describing of a face seals and non-contacting seals. The main part of the thesis describes kinds and reasons of seals testing; also contains comparison between labyrinth seals and piston ring, comparison of seals of PBS Turbo’s turbochargers and assesses the impact of turbocharger angle on the tightness of the seal.

Metco 320 is a AlSi-hBN-polyester abradable, used in the high pressure compressor of commercial gas turbines. The material response to cyclic heating and cooling, and the resulting changes in microstructure, as well as their associated failure mechanisms were investigated. It was found that the top surface layer of the abradable liner degrades over its lifetime. During thermal cycling hBN is removed from the material’s microstructure, which results in the degradation of the abradable and increased brittleness of the top surface. Furthermore, material cracking and delamination behaviour during service was successfully reproduced in the laboratory. The cracking and delamination observations made during overhaul, were replicated using cyclic water-quenching, but the spallation of abradable material did not occur. Investigations into material properties and their influence upon the abradable failure mechanics revealed, that soft M320 matched the observations made during engine overhauls. It could also be established, that the plasma spray process, grit blasting, surface treatment after deposition and the transient of the substrate affect the abradable’s performance and life-time, when heat cycled. Some service casings suffer from premature liner loss. These unscheduled overhauls are costly and their number is desired to be reduced, if possible eliminated. In order to control the material failures, the stresses introduced into the abradable seal during manufacturing need to be reduced, since this is one of main drivers for material cracking and delamination. Furthermore, it was established, that material at the top end of the hardness specification performed better in service. This is due to the fact, that more AlSi metal matrix is present in the microstructure and the hBN loss does not affect the material integrity as much as in soft material. 2D and 3D modelling showed temperature and strain profiles evolving during the quenching process. These show the areas of high strain, which are consistent with the crack initiation areas observed during testing. It can be concluded, that M320 abradable is a very complex material system, which is influenced by several parameters. This research project highlighted, how sensitive the failure modes are to changes in the material/substrate combination. Recommended is to increase the material hardness towards the upper end of the current specification (70 HR15Y), reduce the stresses in the substrate and the abradable material by means of annealing stages after grit blasting, and temperature control during plasma spraying. Furthermore, it would be beneficial to reduce the machining of the abradable’s surface after deposition, as well as carrying out further research into the failure modes of abradables.

У роботі розроблено компресорну установку без змащування циліндрів і сальників.
В работе разработаны компрессорную установку без смазки цилиндров и сальников.
A compressor unit without lubrication of cylinders and glands is developed in the work.

Дисертаційна робота присвячена створенню композитів триботехнічного призначення з підвищеними експлуатаційними властивостями на основі механоактивованих ПТФЕ та наповнювачів різної хімічної природи. Запропоновано підхід підготовки матриці та наповнювачів різної хімічної природи для одержання ПТФЕ-композитів шляхом обґрунтованого вибору співвідношення інгредієнтів та технології їх модифікування. Встановлено оптимальні режими процесу механічної активації матричного ПТФЕ, волокнистих і дисперсних наповнювачів. Вивчено вплив технологічних параметрів процесу механічної активації на структуру, фізико-механічні та триботехнічні властивості ПТФЕ-композиту. З розробленого ПТФЕ-композиту виготовлені поршневі кільця і сальникові ущільнення поршневих компресорів 4ГМ 2,5 У–3,4/2,8–251, які успішно пройшли промислові випробування на ТОВ «Науково-впровадницьке підприємство СумиПластПолімер» і за експлуатаційними характеристиками не поступаються промисловим зразкам.
The thesis is devoted to creation of composites of tribotechnical appointment with the increased operational properties based on mechanically activated polytetrafluoroethylene and fillers of various chemical nature. An approach of preparation of a matrix and fillers of various chemical nature for obtaining PTFE-composites by the reasonable choice of a ratio of ingredients and technology of their modifying is offered. The optimum modes of process of mechanical activation of PTFE-matrix, fibrous and disperse fillers are set. Influence of technological parameters of process of mechanical activation on structure, physical and mechanical and tribotechnical properties of the PTFE-composite is studied. It is shown that under the influence of mechanical activation the ordered spherolitic supramolecular structure of matrix PTFE is formed which is characterized micro- and the nanoscale and leads to an increase in the thermal resistance of a modified polymer on (293–353) K. It is established that mechanical activation does not result in noticeable destruction of polytetrafluoroethylene molecular chain, but there are conformational changes which consist in an increase in concentration of the valent and finite CF2 groups that can lead to enhanced physical, mechanical and service properties of the polymer. It is revealed that the main factors that determine tribotechnical and physical and mechanical properties of PTFE are the time of activation and rotating speed of working organs of a mill. It is mathematically proved the practical experimental mode of mechanical activation at which operational characteristics of matrix PTFE are maximum (n = 9000 min.-1, τ = 5 min.). In comparison with non-activated polymer the level of breaking strength has grown by 2,6 times, relative elongation - by 4,3 times, wear resistances – by 1,86 times. Different technological methods of increasing the adhesive interaction between the ingredients of PTFE-composites are investigated. The prospects of using mechanical activation not only of the matrix but also fillers of various chemical nature for improving of operational characteristics of composites are shown. The determining factor of increase in a complex of operational properties of mechanically activated PTFE-composites is forming spherolitic composite structure under the influence of active particles of disperse layered fillers which playing a role of germs of crystallization and formation on a surface of fibers and coke of the interfacial layer of PTFE which contributes to the emergence of a stable spatial cluster of a filler in volume of a matrix of composition and allows to reach the maximum reinforcing effect, thereby, raising strengthening characteristics of the material and its wear resistance. It is revealed that introduction of a binary filler increases wear resistance of the developed composites by (2,6–4,1) times in comparison with two-component composites. The greatest increase in wear resistance at preservation of high values of physical and mechanical properties of PTFE-composites is watched at synergetic effect of application of mechanical activation of a matrix, fillers, their mixing by two-stage mode and use of a binary filler of various chemical nature. The feature of the developed manufacturing technology of PTFE-composites consists in preliminary separate preparation of a matrix and fillers before their mixing by mechanical activation at various modes of the equipment therefore there is an increase in level of their breaking strength by 1,4 times and wear resistances by (3,7–6,0) times in comparison with industrial analogs that increases durability of work of frictional units of the compressor by (1,8–2,3) times. Piston rings and packing seals of piston-type compressors 4ГМ 2,5 У-3,4/2,8-251 are made of developed PTFE-material that successfully passed industrial tests at LLC «Scientific and innovative enterprise SumyPlastPolymer» and they are not worse than the industry samples. Technological process of PTFE-composite production is developed.
Диссертация посвящена созданию композитов триботехнического назначения с повышенными эксплуатационными свойствами на основе механоактивированных ПТФЭ и наполнителей различной химической природы. Предложен подход подготовки матрицы и наполнителей различной химической природы для получения ПТФЭ-композитов путем обоснованного выбора соотношения ингредиентов и технологии их модифицирования. Установлены оптимальные режимы процесса механической активации матричного ПТФЭ, волокнистых и дисперсных наполнителей. Изучено влияние технологических параметров процесса механической активации на структуру, физико-механические и триботехнические свойства ПТФЭ-композита. Из разработанного ПТФЭ-композита изготовлены поршневые кольца и сальниковые уплотнения поршневых компрессоров 4ГМ 2,5 У–3,4/2,8–251, которые успешно прошли промышленные испытания на ООО «Научно-внедренческое предприятие СумыПластПолимер» и по эксплуатационным характеристикам не уступают промышленным образцам.

В дослідницькій виконано розрахунок варіантів вихрового компресора, досліджено вплив товщини лопаток і частоти обертання ротора на параметри, а також характеристики компресора. Виконано обробку і аналіз результатів випробувань. Розглянуті питання регулювання вихрових компресорів. В розділі охорона праці виконаний аналіз небезпечних та шкідливих промислових факторів, виконаний розрахунок шумоглушнику.
В исследовательской выполнен расчет вариантов вихревого компрессора, исследовано влияние толщины лопаток и частоты вращения ротора на параметры, а также характеристики компрессора. Выполнено обработку и анализ результатов испытаний. Рассмотрены вопросы регулирования вихревых компрессоров. В разделе охрана труда выполнен анализ опасных и вредных промышленных факторов, выполненный расчет шумоглушителю.
In the research, the calculation of the vortex compressor options was carried out, the influence of the blade thickness and rotor speed on the parameters, as well as compressor characteristics, was studied. Processing and analysis of test results has been completed. The issues of regulation of vortex compressors are considered. In the section on labor protection, an analysis of hazardous and harmful industrial factors, a calculation of the silencer is performed.

У дослідній частині поставлені задачі дослідження та виконано теоретичне дослідження. Розглянуто 4-й корпус компресора для тепло насосної утилізації теплоти випарної установки. Наведені результати розрахунків, які виконувалися з використанням розрахункових програм. Використовувався експериментальний стенд для визначення витратних характеристик лабіринтних ущільнень, який необхідний для отримання значень величини витрати протікання при різних режимних і геометричних параметрах. Випробування проводилися на модельних р2=0,1 МПа і натурних р2 = 5,3 МПа умовах. Розбіжності в значеннях коефіцієнтів витрати до 10%. За результатами експериментального дослідження показані розбіжності в значеннях коефіцієнта витрати водяного пару і повітря до 30%. Зі збільшенням частоти обертання валу, коефіцієнт витрати збільшується до 10% на натурних умовах випробування в залежності від робочого середовища. В розділі охорони праці розглянуті питання небезпечних і шкідливих факторів компресорного виробництва. Виконаний розрахунок шуму при витіканні з сопла.
В исследовательской части поставлены задачи исследования и выполнено теоретическое исследование. Рассмотрены 4-й корпус компрессора тепло насосной утилизации теплоты выпарной установки. Приведенные результаты расчетов, которые выполнялись с использованием расчетных программ. Использовался экспериментальный стенд для определения расходных характеристик лабиринтных уплотнений, который необходим для получения значений величины расхода протечки при различных режимных и геометрических параметрах. Испытания проводились на модельных р2 = 0,1 МПа и натурных р2 = 5,3 МПа условиях. Расхождения в значениях коэффициентов расходы до 10%. По результатам экспериментального исследования показаны различия в значениях коэффициента расхода водяного пара и воздуха до 30%. С увеличением частоты вращения вала, коэффициент расхода увеличивается до 10% в натурных условиях испытания в зависимости от рабочей среды.  В разделе охраны труда рассмотрены вопросы опасных и вредных факторов компрессорного производства. Выполнен расчет шума при истечении из сопла.
In the research part, research tasks are set and theoretical research is carried out. The 4th compressor case of the heat pump heat recovery of the evaporator is examined. The results of calculations that were performed using calculation programs. An experimental bench was used to determine the flow characteristics of the labyrinth seals, which is necessary to obtain the values ​​of the leakage flow rate at various operating and geometric parameters. The tests were carried out on model p2 = 0.1 MPa and full-scale p2 = 5.3 MPa conditions. Discrepancies in the values ​​of coefficients of expenses up to 10%. According to the results of an experimental study, differences in the values ​​of the coefficient of flow of water vapor and air up to 30% are shown. With increasing shaft speed, the flow rate increases to 10% in full-scale test conditions depending on the working environment. In the section of labor protection, issues of dangerous and harmful factors of compressor production are considered. The calculation of noise at the outflow from the nozzle is performed.

L'utilisation de revêtements abradables pour assurer l'étanchéité dynamique des turboréacteurs est une solution répandue qui permet d'augmenter la fiabilité et le rendement aérodynamique des turboréacteurs. En fonctionnement, des touches inévitables entre le revêtement et le bout d'aubes de rotor peuvent être à l'origine d'une usure excessive du revêtement abradable et/ou de la rupture d'aube. La simulation numérique de tels incidents butte sur un manque de connaissance des interactions aube/carter et des forces mises en jeu au contact, forces qui résultent notamment de couplages entre le frottement, l'usure du revêtement et des phénomènes vibratoires.Cette thèse a pour objectif de mieux appréhender les mécanismes d'interaction entre l'aube et le revêtement abradable. Elle résulte d'une collaboration entre l'ONERA de Lille et le Laboratoire de Mécanique de Lille et concerne le revêtement de type Al-Si/hbN (Metco 320NS), couramment utilisé dans les compresseurs à basse pression.Les propriétés physico-chimiques et le comportement mécanique - notamment en dynamique - du revêtement abradable sont étudiés. Compte-tenu d'une asymétrie du comportement en traction et en compression, l'exploitation en corrélation d'images numériques d'un essai original inspiré de l'essai Brésilien permet de rendre compte des mécanismes de dégradation. Le comportement tribologique est étudié sur tribomètre dans différentes configurations de contact. L'interaction entre l'aube et le revêtement ainsi que les couplages avec les vibrations d'aube sont investigués et caractérisés dans une configuration simplifiée et fortement instrumentée, sur un banc rotatif spécifique développé à l'ONERA de Lille