Turbomachines

This paper presents the failure analysis of the turbine blade of a gas turbine engine 9E GE type, installed in a certain type of simple systems consisting of the gas turbine driving an electrical power generator. A non-linear finite element method was utilized to determine the stress state of the blade segment under operating conditions. High stress zones were found at the region of the lower fir-tree slot, where the failure occurred. A computation was also performed with excessive rotational speed. Attention of this study is devoted to the mechanisms of damage of the turbine blade and also the critical high stress areas.

Nesta obra apresentam-se as matérias relevantes para um curso avançado de turbomáquinas, incluindo aspetos importantes para o projeto e a análise do seu funcionamento. A informação é exposta de forma sistematizada e analiticamente rigorosa, sendo profusamente ilustrada, facilitando assim a assimilação dos aspetos mais complexos. Utiliza-se uma abordagem pedagógica atual que permite tornar o conhecimento mais acessível a estudantes do ensino universitário e politécnico, assim como aos profissionais da engenharia na sua atividade diária, nas empresas, para autoformação, atualização e consulta.
O livro compreende sete capítulos. Inclui uma visão histórica, apresenta capítulos inteiros dedicados aos ventiladores, bombas, compressores, turbinas a gás centrífugas e axiais, e ainda às turbinas hidráulicas e análise dimensional. O último capítulo trata do projeto computacional avançado de turbomáquinas. Em cada capítulo são apresentados exemplos de exercícios resolvidos.

First, adaptation of an exergy balance initially derived for steady external flows is made to study turbomachine applications. Illustrative examples are given to describe the physical meaning of each term followed by a discussion. Then, application to various components of a propulsion system is proposed focusing on loss mechanisms. Finally, a few perspectives and related developments are discussed.

The paper presents a new exergy-based analysis method for turbomachines internal flow. This method applies to periodic flow inside a turbomachine. After a presentation of the system studied and of the concept of exergy, a balance equation formulation for internal, periodic flow is derived. Then, the results obtained by applying the formulation to computational fluid dynamics (CFD) results, thanks to the ONERA (Office national d'études et de recherches aérospatiales) ffx (Far Field eXegy) tool, are shown. High pressure compressor stator and rotor blades, and a high pressure turbine distributor blade are studied and compared.

Cabin pressure control system of an aircraft maintains cabin pressure in all flight modes as per the aircraft cabin pressurization characteristics by controlling the air flow from the cabin through the outflow valve of the cabin pressure control valve. The movement of outflow valve in turn depends on the air flow from the control chamber of cabin pressure control valve, which is controlled by the clapper and the poppet valves. These valves are actuated by absolute pressure and the differential pressure capsules, respectively depending upon the operating flight conditions. Mathematical models have been developed to simulate the air outflow rates from the cabin and the control chamber of cabin pressure control valve during steady-state and transient flight conditions. These mathematical models have then been translated into a MATLAB program to obtain plots of cabin pressures as a function of aircraft altitudes. The mathematical models are validated for standard cabin pressurization characteristics of a multirole light fighter/trainer aircraft. The model developed, thus can be used to produce a number of variants of cabin pressure control valve to suit different cabin pressurization characteristics.

Within the framework of the French DGA's NECTAR project, SAFRAN Aircraft Engines has access during a test phase to the ONERA's ffx (Far-Field eXergy) tool. This software has been applied to various configurations including those presented in this paper: long duct mixed flow nozzles. On this kind of nozzles, primary and secondary flows are mixed at the confluence before the exhaust. This mixing aims at lower acoustic signature as well as fuel consumption.

A component referred to as a mixer is often added to maximize the mixing. The flow through this component as well as the mixing action itself being complex, it requires optimisation during the design process. As a consequence, an exergy analysis is performed on CFD calculations using a formulation adapted from the one derived for external flows in the PhD Thesis of A. Arntz [1], with applications in [2-5].

This paper presents one of the two first applications of this approach in SAFRAN Aircraft Engines; the second being an assessment of blade performance [6]. One of the challenges in applying this analysis to such devices is to relate the various terms of the exergy balance to more established performance indicators for the design engineer. This is achieved by studying the sensitivity of these terms to geometrical changes, engine speed and thermal exchanges.

Turbo, her türlü araç tipi ve modelinin verimini artmasını sağlayan, yakıt performansını azaltan ve aracın gücü olan bir tür ekipman olarak adlandırılmaktadır. Araçlarda turbo yakıt ve hava karışımını sıkıştırılmasıyla yönlendirilmesi sağlanmaktadır. Bu şekilde aracın daha verimli çalışmasına katkı sağlamış olmaktadır.

Axial flow compressors have a limited operation range due to the difficulty controlling the secondary flow. Vortex generators are considered to control the secondary flow losses and consequently enhance the compressor's performance. In the present work, a numerical simulation of three-dimensional unsteady compressible flow has been developed in order to gain insight into the nature of this flow. Based on the numerical simulation, the effects of vortex generators with variable geometrical parameters and their application inside the cascade are investigated. The predicted flow fields with and without the vortex generators are presented and discussed. For each configuration of vortex generator, the total pressure and loss coefficient are calculated. The predicted velocity and pressure distributions at different locations are compared with the predicted and measured values available in the literatures.

Two similar large steam turbines in an ethylene plant are profiled. One drives the cracked gas compressor train and the other drives the propylene refrigeration compressor. The two machines are similar and this paper concentrates on the turbine driving the cracked gas compressors. Both turbines had a history of high vibration, short bearing life, and unusual sensitivity to thermal changes and imbalance due to operation near the second critical speed. In addition, numerous blade failures had occurred. When additional turbine performance was required, a complete review of the entire turbine including the blade designs, rotordynarnics, and governor operation was commissioned. The performance upgrade included new blading, disks, seals, and other changes to the steam 124 PROCEEDINGS OF THE 28TII TURBOMACHINERY SYMPOSIUM path. A turning gear was added for slow-roll operation to relieve thermal effects and rotor bow. A technique was developed for mounting the turbine disks on the rotor to ...

The article reviews the main forms of flow-induced instabilities detected in the liquid propellant turbopumps systems of modern rocket engines, with special reference to rotating stall, rotating cavitation, cavitation surge and higher order surge modes, illustrating their characteristics, origin and damage potential.

The report on X International Scientific-Practical Conference "Engines and vehicle components: R&D and production, operation and service maintenance". 27-28 June 2017 Protvino, Moscow Region, Russia.
The report gives a brief description of the development of computer software for modeling of wear in the field of radial clearances of small-sized turbomachines when operating with dusty air. A brief description of experimental models intended for verification and testing of the software is presented. [in Russian]