Добірка наукової літератури з теми "Pneumatic starter of a rocket engine"

The article presents the results of the development of diagnostic models of automation elements of liquid-propellant rocket engine power systems. A functional model of a pneumatic valve has been developed, which provides that it is subjected to mechanical action from moving elements, and oscillations in the form of vibration and acoustic waves are observed at the output. The paper presents the results of studies of the dynamics of the mechanical system, which is represented by the valve under study, a mathematical model of the valve closing process, which is a reliable display of the valve's operating characteristics, which it reproduces. The model describes the relationship of the equation of the dynamics of the moving parts of the valve and the occurrence of forced vibrations in its structure and associated elements

ABSTRACTA national initiative is underway to develop and test a more electric aircraft (MEA) and is being led by the U.S. Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio. The MEA concept is based on utilizing electric power to drive aircraft subsystems which are currently driven by a combination of hydraulic, pneumatic, electric and mechanical power transfer systems. A major objective of this effort is to increase military aircraft reliability, maintainability and supportability and to drastically reduce the need for ground support equipment. These improvements will be realized through the further advancement of key MEA technologies, including magnetic bearings, aircraft integrated power units (IPU), and starter/generators (IS/G) internal to an aircraft main propulsion engine. These advanced developments, as well as weapon and space power applications, are the driving force for the new emphasis on high temperature and high strength magnetic materials for power applications. In determining the best magnetic material for an application it is typically necessary to conduct an engineering trade-off analysis which takes into consideration mechanical behavior, electrical loss, and magnetic properties under the conditions of actual usage. New materials solutions are required to meet these challenges, as designers often find the magnetic material performance to be the technological limitation.

Дисертація на здобуття наукового ступеня кандидата технічних наук зі спеціальності 05.05.17 – гідравлічні машини та гідропневмоагрегати. – Національний технічний університет "Харківський політехнічний інститут". – Харків, 2017. Дисертація присвячена дослідженню вдосконаленої пневмосистеми багаторазового запуску маршового рідинного ракетного двигуна верхнього ступеня ракети-носія. Система запуску, яка містить частину пневмоблока двигуна, здійснює розкручування турбонасосного агрегату за рахунок подачі стисненого гелію на його турбіну. Особливістю системи є використання регулятора тиску гелію із пневмокеруванням. Розроблений й реалізований у практиці проектування новий комплекс дискретно-континуальних математичних моделей для газодинамічного розрахунку цієї пневмосистеми, а також аналізу сил тертя й витоків газу у фторопластових манжетних ущільненнях регуляторів. Запропоновано новий розрахунковий метод дослідження пневмосистеми, що проектується, на динамічну стійкість. Досліджені газодинамічні характеристики металлорукава. Розроблено нову концепцію й впроваджено конструкцію лабораторного стенда, що дозволяє економити гелій при доводочних випробуваннях системи. Виконано розрахунково-експериментальне дослідження пневмосистеми, а його рекомендації зі зміни параметрів регулятора, що знижують коливальність і поліпшують інші динамічні характеристики, впроваджені на двигуні.
The thesis for the scientific degree of the Candidate of Technical Sciences by specialty 05.05.17 – hydraulic machines and hydropneumatic units. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2017. The dissertation describes research of perfected pneumatic starting system of a main restartable liquid-propellant rocket engine destined for a launch vehicle upper stage. The starting system, which structure includes a part of the engine pneumatic unit, performs turbopump spin-up by supplying compressed helium to its turbine. A feature of the system is application of a pneumatically controlled helium pressure regulator. New complex of discrete-continual mathematical models is developed and implemented in the designing practice for the gas-dynamic analysis of this pneumatic system and analysis of friction forces and gas leaks through fluoroplastic lip-type seals of regulators. New computational method is proposed for the developed system’s dynamic stability research. The gas-dynamic characteristics of a metal hose are researched. New concept of the laboratory stand is developed and implemented to enable helium saving at development tests. Experimental-computational research of the pneumatic system is performed, recommendations of which are introduced into the engine in relation to the regulator parameters reducing oscillations and improving other dynamic characteristics.

Диссертация на соискание ученой степени кандидата технических наук по специальности 05.05.17 – гидравлические машины и гидропневмоагрегаты. – Национальный технический университет "Харьковский политехнический институт". – Харьков, 2017. Диссертация посвящена исследованию усовершенствованной пневмосистемы многократного запуска маршевого жидкостного ракетного двигателя верхней ступени ракеты-носителя с насосной подачей компонентов топлива в камеру сгорания. Система запуска, в состав которой входит часть пневмоблока двигателя, осуществляет раскрутку турбонасосного агрегата за счет подачи сжатого гелия из шаробаллона на турбину. Особенностью системы является использование регулятора давления гелия с пневмоуправлением. Исследованная система обеспечивает пять включений двигателя РД861К при идентичных импульсах давления подачи газа, имеющих прямоугольную вершину и предельно крутые фронты. Разработан и использован в практике проектирования новый комплекс дискретно-континуальных математических моделей для газодинамического расчета этой пневмосистемы, а также анализа сил трения и утечек газа во фторопластовых манжетных уплотнениях регуляторов. В моделях учтены новые эффекты: теплообмен газа со стенками полостей и трубопроводов; инерционность газа при его выпуске из баллона; фактор сжимаемости гелия; нагрев гелия при дросселировании; проникновение уплотняемого давления в зазор между манжетой и стенкой, и ряд других. После чего отклонение расчетных значений давления газа от результатов огневых испытаний составило менее 1% Создана и реализована расчетная методика исследования пневмосистемы на динамическую устойчивость и автоколебания. В методике использованы уточненные результаты гармонической линеаризации для колебаний расхода газа через дроссель и силы трения в манжете, а также новый метод расчета импеданса разветвленной системы трубопроводов. Выведено трансцендентное уравнение для частот и амплитуд свободных нелинейных колебаний системы и предложены методы его решения. Точность определения частот автоколебаний составила 2%. Получены аналитические соотношения для параметров пневмосистемы, обеспечивающие динамическую устойчивость или автоколебания малой амплитуды. Исследованы газодинамические характеристики металлорукава, используемого в дренажной системе лабораторного стенда для исследования и настройки системы. Разработана новая концепция и внедрена конструкция стенда, позволяющая экономить гелий при доводочных испытаниях системы. Выполнено расчетно-экспериментальное исследование системы, а его рекомендации по изменению параметров регулятора, снижающие колебательность и улучшающие другие динамические характеристики, внедрены на двигателе.
The thesis for the scientific degree of the Candidate of Technical Sciences by specialty 05.05.17 – hydraulic machines and hydropneumatic units. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2017. The dissertation describes research of perfected pneumatic starting system of a main restartable liquid-propellant rocket engine destined for a launch vehicle upper stage. The starting system, which structure includes a part of the engine pneumatic unit, performs turbopump spin-up by supplying compressed helium to its turbine. A feature of the system is application of a pneumatically controlled helium pressure regulator. New complex of discrete-continual mathematical models is developed and implemented in the designing practice for the gas-dynamic analysis of this pneumatic system and analysis of friction forces and gas leaks through fluoroplastic lip-type seals of regulators. New computational method is proposed for the developed system’s dynamic stability research. The gas-dynamic characteristics of a metal hose are researched. New concept of the laboratory stand is developed and implemented to enable helium saving at development tests. Experimental-computational research of the pneumatic system is performed, recommendations of which are introduced into the engine in relation to the regulator parameters reducing oscillations and improving other dynamic characteristics.

Electric, pneumatic, combustion, and hydraulic systems are commonly used as gas turbine engine starters. All such starters must allow full-load engine operation to be reached within few or several minutes, depending on the size and type of the engine. This contrast in the power source of these starters imposes a variation in their operations including control procedures and safety measures such as blow-downs and on/off sequences. Driving characteristics such as dynamic and static behaviors of these starters also vary significantly, depending on the type of starter and the size or configuration (single or multiple shafts) of the engine to be started. This paper provides an overall comparative background of the commonly available gas turbine engine starters. It also presents numerical results comparing hot start characteristics of single, two, and three shaft engines with cold and hot ends. The possibility of a safe engine hot starting is a valid asset in some service areas, mainly military applications. The comparisons include starter power and gas producer speed (NGP) as the function of engine acceleration, and also starter torque as a function of the % NGP. Fuel consumption of the engine during the hot start is simulated and presented as a function of the load. The impact of an engine configuration on engine starting characteristics is implicated.

A mechanical start system has been developed to start the Ship’s Service Gas Turbine Generators (SSGTG) on board U.S. naval destroyers. The current starting system uses either stored high pressure air or bleed air from another running turbine. The U.S. Navy has reviewed the high pressure air system and found it to be a costly system for both ship construction and maintenance. As a result, the Navy is requiring an alternative starting method that will replace high pressure air. It should be noted that any alternative that introduces compressed air to start the SSGTG depends on the start air regulating assembly and the pneumatic starter. The Redundant Independent Mechanical Start System (RIMSS) consists of an Allison Model 250 turboshaft engine mounted above the SSGTG main reduction gearbox. The turboshaft power take off is connected to the pinion shaft of the reduction gearbox by means of a parallel shaft auxiliary transfer gearbox. The transfer gearbox connection to the reduction gearbox replaces the pneumatic starter adapter pad but provides a means to also connect the pneumatic starter. As a result, the pinion shaft can be driven either pneumatically by the air turbine or mechanically by the Model 250 engine. This provides an alternative starting mode which is totally independent of the present means of starting. This will increase the reliability and availability of the SSGTG since it can still be started even if the pressure regulator or the pneumatic starter is not functional. This system has undergone testing at the Naval Surface Warfare Center Carderock Division facility in Philadelphia.

More electric and all electric aircraft were already discussed in the eighties of the last century, but recent political and ecological issues now reinforce the electrification of aircraft and engine systems. The development of electric machines and components with increasing power to weight ratio enables the installation of power optimized electric accessories instead of pneumatic and hydraulic systems in order to raise overall efficiency and specific fuel consumption of the engine. While pneumatic and hydraulic components are driven by the aircraft engine, a major challenge is in the supply of electric energy. Storage systems lack in reliability and light weight, fuel cell technology is limited to small aircraft and needs further development in various technical disciplines. An appropriate option is the generation of electric power by engine integrated generators. Performance calculations state increased efficiency by means of split spool power offtake, but have not been validated by a real twin-spool demonstrator yet. At the ground test facility of the Institute of Jet Propulsion a demonstrator engine has been set up for detailed research on the influence of power extraction from a Larzac 04 C5 jet engine. To facilitate the test vehicle for power offtake of two spools the starter-generator has been complemented by a second generator, which is installed in front of the compressor inlet. It is axially connected to the low pressure spool by a coupling and a special flange mounted onto the low pressure spool. Several subsystems enabling for electric power offtake are integrated into the facilities’ data acquisition system (DAQ) and communication structure. The added components influence the engine in various ways: They manipulate power balance of the spools and alter the inlet pressure distribution and the compressor aerodynamics. Additionally the internal flow distribution is changed as well as the vibration characteristics. Before starting with extensive more electric engine (MEE) power offtake test campaigns, all systems need to be installed and tested successively. This paper describes the test facility and fundamental more electric engine subsystems, with special focus put on instrumentation and system communication. A first function test demonstrates the operability of the engine after the modification of the low pressure spool. In a further step the influence of the inlet modification onto the compressor inlet aerodynamics, total mass flow, and vibrations of the test vehicle is analyzed. The vibration characteristics are vital for the coupling functionality, which is demonstrated subsequently. Presenting the load system check, special focus is given to communication, load definition, and electromagnetic compatibility. Comparisons to component performance predictions and to the performance of the original engine configuration are drawn for all tests and new limits for the operation of the new more electric configuration are defined. Finally, first data of power offtake of two spools is presented to demonstrate the operability of the MEE test vehicle.

Main powerplants for aircraft in the US Navy inventory typically require a source of pneumatic power in order to initiate the engine start sequence. The equipment which is used as the source for this power is termed “UNIJASU”, or Universal Jet Aircraft Start Unit. UNIJASU is a fully self-contained, transportable source of ground power which may be adapted to both land or carrier-based operations. At the nucleus of this unit is a modified T53 aircraft gas turbine, originally developed and fielded by the Lycoming Turbine Engine Division of Stratford Conn. In the current application, the T53 has been re-configured as a gas generator with specific provisions for extensive operation in a marine environment. Using the bleed machine concept, up to 30% of the engine massflow (equating to roughly 420 air horsepower) can be delivered to an aircraft starter upon demand. The present production source for the T53 engine is the AlliedSignal Engine Company, located at Phoenix, Az. As of the writing date (mid-1997), the US Navy is in the process of procuring its next generation air start units via contract to AlliedSignal. This paper describes the salient features of a rigorous two-phase development program starting with the initial adaptation of the aircraft turbine engine to a naval ground power unit, and culminating with over 6000hrs of system level testing, inclusive of actual field evaluations.

The LM2500 gas turbine has been used on Italian Navy (ITN) ships for more than twenty years. The first engines were installed onboard the “Lupo” class Frigates during the second half of the 1970’s. These gas turbines are operated by means of a Hydro-Mechanical Fuel Control (HMFC) system and started by a pneumatic starter. However, it is known that in some of the latest applications of the LM2500 gas turbines, (e.g. direct drive and water jet systems - Military Sealift Command LMSR cargo vessels and Tirrenia Ferries), electronic fuel control systems and hydraulic starters are used to improve the control and maintenance of the engine, and to reduce the number of air bottles and compressors that have to be installed. The ITN is now evaluating the convenience of using the electronic fuel control systems and hydraulic starters in future surface combatant applications (cruisers, destroyers & frigates) of FIAT GE LM2500 gas turbines. This paper describes the comparison between the different systems that have been carried out by the ITN in the following fields: operations, maintenance and cost effectiveness.