Application of Creativity Tools to Gas Turbine Engine Compressor Clearance Control

Author(s):  
Godwin I. Ekong ◽  
Christopher A. Long ◽  
Peter R. N. Childs

Creativity tools are methods that can be used to promote innovative products and creative actions. There is a wide range of tools available for idea generation, employing divergent and convergent thinking for problem definition, exploration of problem features, generation of solution options, evaluation and implementation of ideas. Fundamental to their effective operation is to make use of a suitable creativity tool for a particular application and individual or team, to aid in the process of problem-solving, the refinement of old ideas, and the generation and implementation of new ideas. The principal creativity tool described in this paper is TRIZ which is the Russian acronym for Teoriya Resheniya Izobretatelskikh Zadatch meaning Theory of Inventive Problem Solving. This paper emphasizes the processes and specific TRIZ tools used in the implementation of TRIZ in the exploration of concepts for tip clearance control in gas turbine high pressure compressors in aircraft engines. The TRIZ process was used to categorize ideas generated through divergent thinking thus reducing the number of ideas carried forward for further engineering analysis.

1994 ◽  
Vol 116 (4) ◽  
pp. 629-634 ◽  
Author(s):  
G. Eisenlohr ◽  
H. Chladek

To master today’s demand for efficiency and compactness of centrifugal compressor components for small gas turbine engines the main attention must not only be given to the aerodynamic design of the impeller and diffuser components, but also to the installation situation of the surrounding parts. A vital aspect is the tip clearance control between impeller and shroud casing over the total operating range. Using the radial compressor for a small gas turbine engine, developed at BMW Rolls-Royce, the importance of tip clearance control is demonstrated. The possibilities for influencing and optimizing passive tip clearance control by design features are described; transient expansion processes must be considered when using a thermal tip clearance control. The results of the design calculations are compared with the results on the test stand and the engine itself. An effort is made to find a qualitative influence of tip clearance to the engine power output at operating conditions. This qualitative description is substantiated by test results with different tip clearances at the compressor teststand.


Author(s):  
P. A. Phillips ◽  
Peter Spear

After briefly summarizing worldwide automotive gas turbine activity, the paper analyses the power plant requirements of a wide range of vehicle applications in order to formulate the design criteria for acceptable vehicle gas turbines. Ample data are available on the thermodynamic merits of various gas turbine cycles; however, the low cost of its piston engine competitor tends to eliminate all but the simplest cycles from vehicle gas turbine considerations. In order to improve the part load fuel economy, some complexity is inevitable, but this is limited to the addition of a glass ceramic regenerator in the 150 b.h.p. engine which is described in some detail. The alternative further complications necessary to achieve satisfactory vehicle response at various power/weight ratios are examined. Further improvement in engine performance will come by increasing the maximum cycle temperature. This can be achieved at lower cost by the extension of the use of ceramics. The paper is intended to stimulate the design application of the gas turbine engine.


Author(s):  
G. J. Sturgess

The paper deals with a small but important part of the overall gas turbine engine combustion system and continues earlier published work on turbulence effects in film cooling to cover the case of film turbulence. Film cooling of the gas turbine combustor liner imposes certain geometric limitations on the coolant injection device. The impact of practical film injection geometry on the cooling is one of increased rates of film decay when compared to the performance from idealized injection geometries at similar injection conditions. It is important to combustor durability and life estimation to be able to predict accurately the performance obtainable from a given practical slot. The coolant film is modeled as three distinct regions, and the effects of injection slot geometry on the development of each region are described in terms of film turbulence intensity and initial circumferential non-uniformity of the injected coolant. The concept of the well-designed slot is introduced and film effectiveness is shown to be dependent on it. Only slots which can be described as well-designed are of interest in practical equipment design. A prediction procedure is provided for well-designed slots which describes growth of the film downstream of the first of the three film regions. Comparisons of predictions with measured data are made for several very different well-designed slots over a relatively wide range of injection conditions, and good agreement is shown.


Author(s):  
Godwin Ita Ekong ◽  
Christopher A. Long ◽  
Peter R. N. Childs

Compressor tip clearance for a gas turbine engine application is the radial gap between the stationary compressor casing and the rotating blades. The gap varies significantly during different operating conditions of the engine due to centrifugal forces on the rotor and differential thermal expansions in the discs and casing. The tip clearance in the axial flow compressor of modern commercial civil aero-engines is of significance in terms of both mechanical integrity and performance. In general, the clearance is of critical importance to civil airline operators and their customers alike because as the clearance between the compressor blade tips and the casing increases, the aerodynamic efficiency will decrease and therefore the specific fuel consumption and operating costs will increase. This paper reports on the development of a range of concepts and their evaluation for the reduction and control of tip clearance in H.P. compressors using an enhanced heat transfer coefficient approach. This would lead to improvement in cruise tip clearances. A test facility has been developed for the study at the University of Sussex, incorporating a rotor and an inner shaft scaled down from a Rolls-Royce Trent aero-engine to a ratio of 0.7:1 with a rotational speed of up to 10000 rpm. The idle and maximum take-off conditions in the square cycle correspond to in-cavity rotational Reynolds numbers of 3.1×106 ≤ Reφ ≤ 1.0×107. The project involved modelling of the experimental facilities, to demonstrate proof of concept. The analysis shows that increasing the thermal response of the high pressure compressor (HPC) drum of a gas turbine engine assembly will reduce the drum time constant, thereby reducing the re-slam characteristics of the drum causing a reduction in the cold build clearance (CBC), and hence the reduction in cruise clearance. A further reduction can be achieved by introducing radial inflow into the drum cavity to further increase the disc heat transfer coefficient in the cavity; hence a further reduction in disc drum time constant.


Author(s):  
Yoichiro Ohkubo ◽  
Osamu Azegami ◽  
Hiroshi Sato ◽  
Yoshinori Idota ◽  
Shinichiro Higuchi

A 300 kWe class gas turbine which has a two-shaft and simple-cycle has been developed to apply to co-generation systems. The gas turbine engine is operated in the range of about 30% partial load to 100% load. The gas turbine combustor requires a wide range of stable operations and low NOx characteristics. A double staged lean premixed combustor, which has a primary combustion duct made of Si3N4 ceramics, was developed to meet NOx regulations of less than 80 ppm (corrected at 0% oxygen). The gas turbine with the combustor has demonstrated superior low-emission performance of around 40 ppm (corrected at 0% oxygen) of NOx, and more than 99.5% of combustion efficiency between 30% and 100% of engine load. Endurance testing has demonstrated stable high combustion performance over 3,000 hours in spite of a wide compressor inlet air temperature (CIT) range of 5 to 35 degree C.. While increasing the gas generator turbine speed, the flow rate of primary fuel was controlled to hold a constant equivalence ratio of around 0.5 in the CIT range of more than 15 C. The output power was also decreased while increasing the CIT, in order to keep a constant temperature at the turbine inlet. The NOx decreases in the CIT range of more than 15 C. On the other hand, the NOx increases in the CIT range of less than 15 C when the output power was kept a constant maximum power. As a result, NOx emission has a peak value of about 40 ppm at 15 C.


Author(s):  
J. E. Donald Gauthier

This paper describes the results of modelling the performance of several indirectly fired gas turbine (IFGT) power generation system configurations based on four gas turbine class sizes, namely 5 kW, 50 kW, 5 MW and 100 MW. These class sizes were selected to cover a wide range of installations in residential, commercial, industrial and large utility power generation installations. Because the IFGT configurations modelled consist of a gas turbine engine, one or two recuperators and a furnace; for comparison purpose this study also included simulations of simple cycle and recuperated gas turbine engines. Part-load, synchronous-speed simulations were carried out with generic compressor and turbine maps scaled for each engine design point conditions. The turbine inlet temperature (TIT) was varied from the design specification to a practical value for a metallic high-temperature heat exchanger in an IFGT system. As expected, the results showed that the reduced TIT can have dramatic impact on the power output and thermal efficiency when compared to that in conventional gas turbines. However, the simulations also indicated that several configurations can lead to higher performance, even with the reduced TIT. Although the focus of the study is on evaluation of thermodynamic performance, the implications of varying configurations on cost and durability are also discussed.


Author(s):  
Kyle Kitzmiller ◽  
Fletcher Miller

In recent years, several prototype solar central receivers have been experimentally demonstrated to produce high temperature and high pressure gas capable of driving a gas turbine engine [1–4]. While these prototype receivers are generally small (< 1 MWth), advancements in this technology will allow for the development of solar powered gas turbine engines at a commercial level (sizes of at least several megawatts electric (MWe)). The current paper analyzes a recuperated solar powered gas turbine engine, and addresses engine considerations, such as material limitations, as well as the variable nature of solar input. In order to compensate for changes in solar input, two operational strategies are identified and analyzed. The first is hybridization, meaning the solar input is supplemented via the combustion of fossil fuels. Hybridization often allows for an increase in net power and efficiency by adding heat during periods of low solar thermal input. An alternative strategy is to make use of variable guide vanes on the compressor of the gas turbine engine, which schedule to change the air flow rate into the system. By altering the mass flow rate of air, and assuming a fixed level of heat addition, the operating temperature of the engine can be controlled to maximize power or efficiency. The paper examines how to combine hybridization with variable guide vane operation to optimize gas turbine performance over a wide range of solar thermal input, from zero to solar-only operation. A large material constraint is posed by the combustor, and to address this concern two alternative strategies — one employing a bypass valve and the other a combustor modified to allow higher temperature inlet air — are presented. Combustor modifications could include new materials and/or increased cooling air. The two strategies (bypass vs. no bypass) are compared on a thermodynamic basis. Finally, a yearly assessment of solar share and thermodynamic performance is presented for a 4.8 MWe gas turbine to identify the overall benefits of the operational strategies.


1980 ◽  
Vol 102 (3) ◽  
pp. 524-534 ◽  
Author(s):  
G. J. Sturgess

The paper deals with a small but important part of the overall gas turbine engine combustion system and continues earlier published work on turbulence effects in film cooling to cover the case of film turbulence. Film cooling of the gas turbine combustor liner imposes certain geometric limitations on the coolant injection device. The impact of practical film injection geometry on the cooling is one of increased rates of film decay when compared to the performance from idealized injection geometries at similar injection conditions. It is important to combustor durability and life estimation to be able to predict accurately the performance obtainable from a given practical slot. The coolant film is modeled as three distinct regions, and the effects of injection slot geometry on the development of each region are described in terms of film turbulence intensity and initial circumferential non-uniformity of the injected coolant. The concept of the well-designed slot is introduced and film effectiveness is shown to be dependent on it. Only slots which can be described as well-designed are of interest in practical equipment design. A prediction procedure is provided for well-designed slots which describes growth of the film downstream of the first of the three film regions. Comparisons of predictions with measured data are made for several very different well-designed slots over a relatively wide range of injection conditions, and good agreement is shown.


Aviation ◽  
2013 ◽  
Vol 17 (2) ◽  
pp. 52-56 ◽  
Author(s):  
Mykola Kulyk ◽  
Sergiy Dmitriev ◽  
Oleksandr Yakushenko ◽  
Oleksandr Popov

A method of obtaining test and training data sets has been developed. These sets are intended for training a static neural network to recognise individual and double defects in the air-gas path units of a gas-turbine engine. These data are obtained by using operational process parameters of the air-gas path of a bypass turbofan engine. The method allows sets that can project some changes in the technical conditions of a gas-turbine engine to be received, taking into account errors that occur in the measurement of the gas-dynamic parameters of the air-gas path. The operation of the engine in a wide range of modes should also be taken into account.


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