Power Turbine Vane Ring (PT6 Engine) Repair Development

Author(s):  
N. Sourial

Today’s high technology gas turbine engines incorporate the world’s most exotic alloys and are built to some of the most precise dimensional tolerances encountered in any industry. The constant drive for increased performance while substantially reducing fuel consumption and weight has pushed engine components and their designers to limits never before realized. To achieve these limits new methods and materials have evolved; not exclusively in the production of the engines but also in the repair and maintenance of them. The typical problems encountered in repair and maintenance are numerous and varied as are their solutions. This paper, however, will concentrate on one in particular and that is the typical damage encountered on a first stage power turbine vane ring and the technology employed to repair such damage. The vane ring was chosen because it is representative of a common problem encountered by all gas turbine engine manufacturers and simultaneously involves some of the most up to date repair techniques to restore it.

Author(s):  
Youry A. Nozhnitsky ◽  
Youlia A. Fedina ◽  
Anatoly D. Rekin ◽  
Nickolai I. Petrov

For years of time there have been conducted the investigations of gas-turbine engine parts made of carbon-carbon and ceramic materials. This paper presents mainly the results of works done to create engine components of ceramic materials. There are given the investigation results on development of equipment and methods intended for use in determining the characteristics of heat-resistant non-metallic materials under ultra high temperature conditions. The unique tooling is developed to be used for conducting mechanical tests in different conditions (vacuum, protective medium, air) at temperatures up to 2200°C. There are considered three possible fields of application of ceramic materials, that are, turbine (1), combustion chamber and other stator components operating at high temperatures (2), bearings (3). Different ceramic elements are designed and manufactured, their structural strength is investigated in the laboratory faculties and also as part of engine gas generators.


Author(s):  
Michael P. Enright ◽  
R. Craig McClung ◽  
Luc Huyse

Rare anomalies may be introduced during the metallurgical or manufacturing processes that may lead to uncontained failures of aircraft gas turbine engines. The risk of fracture associated with these anomalies can be quantified using a probabilistic fracture mechanics approach. In this paper, a general probabilistic framework is presented for risk assessment of gas turbine engine components subjected to either inherent or induced material anomalies. A summary of efficient computational methods that are applicable to this problem is also provided.


Author(s):  
O. Andriets ◽  
V. Matviienko ◽  
V. Ocheretianyi

Gas-turbine engines (GTE) posses a number of technical merits and they are widely used in the structure of ship propulsion complexes. However, if GTE is used as a ship cruise engine it is necessary to increase efficiency with the goal to be competitive to diesels. Increasing of the simple cycle GTE efficiency is possible due to the overexpansion turbine employment, where the internal energy of exhaust gases is used. That allows to obtain, deducting energy expenses on exhaust gases pressing, the additional useful work without the additional fuel expenses. Power overexpansion turbine employment leads to raising of power plant heaviness, that’s why it is desirable to increase engine power when its weight is constant. Insertion of the intermediate gas reheating before power turbine in the thermal scheme of GTE with the power overexpansion turbine considerably increases GTE’s specific power. GTE with the intermediate gas reheating before the power overexpansion turbine have greater specific power and they are more economic than simple cycle’s GTE on a large spectrum of ship’s power plant operating regimes. GTE with intermediate gas reheating before the power overexpansion turbine have stable efficiency on operating regimes, that’s why it is preferable to employ them for hydrofoil ships.


Author(s):  
J. R. Palmer ◽  
Yong-Gen Gu

This paper presents a computer model called ‘TURBOTEST’ which is applicable both to analysis of gas turbine engine rig tests and to simulation of engine steady-state performance. As with the earlier ‘TURBOFLEXI’ model a wide range of gas turbine engines can be simulated, using any kind of hydrocarbon fuel, and allowing for chemical dissociation of the gas, and for the effect of air humidity. In addition, however, for the particular requirements of rig test analysis, the following new features have been developed and incorporate:- (a) It can carry out rig test analysis for a wide range of gas turbine engines if all the necessary test data are presented. (b) If the test data is incomplete, a computer simulation of the engine can be used to complete the analysis. (c) Performance deterioration of engine components can be detected by comparing the results of a test analysis and of a parallel simulation using stored characteristics of engine components in the “as new” condition. The program has been tested on simulated test data generated by engine models such as a turbojet and a turbofan. The results show it has close and repeatable agreement with design values. Further tests of the model have been carried out by applying it to the actual engine rig test data.


Author(s):  
A. F. McLean

This paper reviews the limitations today’s superalloys exercise on the realization of the potential of the gas turbine engine. Ceramic materials are suggested as a means of achieving lower cost and higher turbine inlet temperature in small gas turbine engines. The paper serves to introduce ceramic materials and processing techniques and identifies silicon nitride, silicon carbide and lithium-alumina-silicate as promising materials for high temperature turbine engine components.


Author(s):  
Xiying Niu ◽  
Feng Lin ◽  
Weishun Li ◽  
Chen Liang ◽  
Shunwang Yu ◽  
...  

Gas turbine engines are widely used as the marine main power system. However, they can’t reverse like diesel engine. If the reversal is realized, other ways must be adopted, for example, controllable pitch propeller (CPP) and reversible gearing. Although CPP has widespread use, the actuator installation inside the hub of the propeller lead to the decrease in efficiency, and it takes one minute to switch “full speed ahead” to “full speed astern”. In addition, some devices need to be added for the reversible gearing, and it takes five minutes to switch from “full speed ahead” “to “full speed astern”. Based on the gas turbine engine itself, a reversible gas turbine engine is proposed, which can rotate positively or reversely. Most important of all, reversible gas turbine engine can realize operating states of “full speed ahead”, “full speed astern“ and “stop propeller”. And, it just takes half of one minute to switch “full speed ahead” to “full speed astern”. Since reversible gas turbine engines have compensating advantages, and especially in recent years computational fluid dynamics (CFD) technology and turbine gas-dynamics design level develop rapidly, reversible gas turbine engines will be a good direction for ship astern. In this paper, the power turbine of a marine gas turbine engine was redesigned by three dimensional shape modification, and the flow field is analyzed using CFD, in order to redesign into a reverse turbine. The last stage vanes and blades of this power turbine were changed to double-layer structure. That is, the outer one is reversible turbine, while the inner is the ahead one. Note that their rotational directions are opposite. In order to realize switching between rotation ahead and rotation astern, switching devices were designed, which locate in the duct between the low pressure turbine and power turbine. Moreover, In order to reduce the blade windage loss caused by the reversible turbine during working ahead, baffle plates were used before and after the reversible rotor blades. This paper mainly studied how to increase the efficiency of the reversible turbine stage, the torque change under different operating conditions, rotational speed and rotational directions, and flow field under typical operating conditions. A perfect profile is expected to provide for reversible power turbine, and it can decrease the blade windage loss, and increase the efficiency of the whole gas turbine engine. Overall, the efficiency of the newly designed reversible turbine is up to 85.7%, and the output power is more than 10 MW, which can meet requirements of no less than 30% power of rated condition. Most importantly, the shaft is not over torque under all ahead and astern conditions. Detailed results about these are presented and discussed in the paper.


2020 ◽  
Vol 2020 (8) ◽  
pp. 42-48
Author(s):  
Vyacheslav Bezyazychnyy ◽  
Andrey Smirnov

There are presented technological (requirements in new technologies for repair of gas turbine engines (GTE) repaired according to a technical state, growing requirements on reliability, high cost of repair, a limited access to new technologies) and organization (absence of repair localization, high competition etc.) problems of aircraft gas turbine engine repair. The direction for updating: development of new repair technologies at the transition to the concept of repair on a technical state; module technology application; repair production localization; creation of flexible repair techniques etc. is considered.


Author(s):  
Philippe Mathieu ◽  
Pericles Pilidis

In this paper, the use of various gaseous fuels in aero-derivative gas turbine engines is analysed. The gases investigated are natural gas and three coal synthetic gases of calorific values which are significantly lower than that of natural gas. The analysis is carried out employing natural gas fuel as a yardstick for comparison. Due to the lower calorific values of synthetic gases, the mass flow balance between compressors and turbines is altered. This in turn affects the matching of the components and the overall performance of a gas turbine engine. The engines examined are a single spool gas generator with a free power turbine and the double engine described in a previous paper. The main conclusion drawn from this analysis is that, for a given power output, the use of synthetic gases will result in an erosion of surge margins and in a reduction of the overall efficiency of the power plant.


2021 ◽  
pp. 1-11
Author(s):  
Jacob Elms ◽  
Alison Pawley ◽  
Nicholas Bojdo ◽  
Merren Jones ◽  
Rory J. Clarkson

Abstract The ingestion of multi-mineral dusts by gas turbine engines during routine operations is a significant problem for engine manufacturers because of the damage caused to engine components and their protective thermal barrier coatings. A complete understanding of the reactions forming these deposits is limited by a lack of knowledge of compositions of ingested dusts and unknown engine conditions. Past engine tests have used standardised test dusts that do not resemble the composition of the background dust in the operating regions. A new evaporite-rich test dust was developed and used in a full engine ingestion test, designed to simulate operation in regions with evaporite-rich geology, such as Doha or Dubai. Analysis of the engine deposits showed that mineral fractionation was present in the cooler, upstream sections of the engine. In the hotter, downstream sections, deposits contained new, high temperature phases formed by reaction of minerals in the test dust. The mineral assemblages in these deposits are similar to those found from previous analysis of service returns. Segregation of anhydrite from other high temperature phases in a deposit sample taken from a High Pressure Turbine blade suggests a relationship between temperature and sulfur content. This study highlights the potential for manipulating deposit chemistry to mitigate the damage caused in the downstream sections of gas turbine engines. The results of this study also suggest that the concentration of ingested dust in the inlet air may not be a significant contributing factor to deposit chemistry.


Author(s):  
H. A. Johnson ◽  
G. K. Bhat

At the present time, virtually all superalloys used in Soviet gas turbine engines have been electroslag remelted. The use of this process in the United States has been at a virtual standstill since its inception by Hopkins in 1935. This paper will cover recent development effort on the process and what it offers to the industry. The process itself will be described in detail. Included also will be its advantages, both in metalworking and resultant mechanical properties obtained on actual gas turbine engine components fabricated from electroslag remelted superalloys.


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