scholarly journals Modular Simulation of Coolant Internal Network and Rotating Cavity Analysis

Author(s):  
Carlo Carcasci ◽  
Ennio Carnevale ◽  
Bruno Facchini ◽  
Giovanni Ferrara

The increase in gas turbine performance requires very high total inlet temperatures even in heavy-duty applications. Therefore, an accurate design of both the blade cooling and the cooling network from the compressor to the blade is very important. In previous works, the authors have studied the cooling blade problems for both the stator and the rotor case. The present paper presents a simple and fast procedure to study the cooling network: a modular code has been developed for this purpose and particular attention has been focused on the study o the rotating cavities between the stator and the rotating disks. The results we have obtained are good and the code developed is at present used in industry.

Author(s):  
Francesco Farina ◽  
Franco Donatini

A preliminary procedure has been developed to analyse the cooling of both nozzle and rotor blades in a gas turbine, evaluating the influence of the system on the performance of the machine. The developed method, which is based on a second law approach, defines the effects of the thermodynamic losses due to the forced convection air blade cooling on the performance of a typical heavy duty gas turbine in terms of lost exergy as function of the turbine inlet temperature.


Author(s):  
Joachim Kurzke

Precise simulations of gas turbine performance cannot be done without component maps. In the early days of a new project one often has to use scaled maps of similar machines. Alternatively one can calculate the component partload characteristics provided that the many details needed for such an exercise are available. In a later stage often rig tests will be done to get detailed information about the behavior of the compressors respectively turbines. Performance calculation programs usually require the map data in a specific format. To produce this format needs some preprocessing. Measured data cannot be used directly because they show a scatter and they are not evenly distributed over the range of interest. Due to limitations in the test equipment often there is lack of data for very low and very high speed. With the help of a specialized drawing program available on a PC one can easily eliminate the scatter in the data and also inter- and extrapolate additional lines of constant corrected speed. Many graphs showing both the measured data and the lines passing through the data as a function of physically meaningful parameters allow to check whether the result makes sense or not. The extrapolation of compressor maps toward very low speed, as required for the calculation of starting, idle and windmilling performance calculations, is discussed in some detail. Instead of true measured data one can use data read from maps published in open literature. The program is also an excellent tool for checking and extending component maps one has derived from sparse information about a gas turbine to be simulated.


Author(s):  
Wolfgang Kappis ◽  
Stefan Florjancic ◽  
Uwe Ruedel

Market requirements for the heavy duty gas turbine power generation business have significantly changed over the last few years. With high gas prices in former times, all users have been mainly focusing on efficiency in addition to overall life cycle costs. Today individual countries see different requirements, which is easily explainable picking three typical trends. In the United States, with the exploitation of shale gas, gas prices are at a very low level. Hence, many gas turbines are used as base load engines, i.e. nearly constant loads for extended times. For these engines reliability is of main importance and efficiency somewhat less. In Japan gas prices are extremely high, and therefore the need for efficiency is significantly higher. Due to the challenge to partly replace nuclear plants, these engines as well are mainly intended for base load operation. In Europe, with the mid and long term carbon reduction strategy, heavy duty gas turbines is mainly used to compensate for intermittent renewable power generation. As a consequence, very high cyclic operation including fast and reliable start-up, very high loading gradients, including frequency response, and extended minimum and maximum operating ranges are required. Additionally, there are other features that are frequently requested. Fuel flexibility is a major demand, reaching from fuels of lower purity, i.e. with higher carbon (C2+), content up to possible combustion of gases generated by electrolysis (H2). Lifecycle optimization, as another important request, relies on new technologies for reconditioning, lifetime monitoring, and improved lifetime prediction methods. Out of Alstom’s recent research and development activities the following items are specifically addressed in this paper. Thermodynamic engine modelling and associated tasks are discussed, as well as the improvement and introduction of new operating concepts. Furthermore extended applications of design methodologies are shown. An additional focus is set ono improve emission behaviour understanding and increased fuel flexibility. Finally, some applications of the new technologies in Alstom products are given, indicating the focus on market requirements and customer care.


Author(s):  
Maryam Besharati-Givi ◽  
Xianchang Li

The increase of power need raises the awareness of producing energy more efficiently. Gas turbine has been one of the important workhorses for power generation. The effects of parameters in design and operation on the power output and efficiency have been extensively studied. It is well-known that the gas turbine inlet temperature (TIT) needs to be high for high efficiency as well as power production. However, there are some material restrictions with high-temperature gas especially for the first row of blades. As a result blade cooling is needed to help balance between the high TIT and the material limitations. The increase of TIT is also limited by restriction of emissions. While the blade cooling can allow a higher TIT and better turbine performance, there is also a penalty since the compressed air used for cooling is removed from the combustion process. Therefore, an optimal cooling flow may exist for the overall efficiency and net power output. In this paper the relationship between the TIT and amount of cooling air is studied. The TIT increase due to blade cooling is considered as a function of cooling air flow as well as cooling effectiveness. In another word, the increase of the TIT is limited while the cooling air can be increased continuously. Based on the relationship proposed the impact of blade cooling on the gas turbine performance is investigated. Compared to the simple cycle case without cooling, the blade cooling can increase the efficiency from 28.8 to 34.0% and the net power from 105 to 208 MW. Cases with different operation conditions such as pressure ratios as well as design aspects with regeneration are considered. Aspen plus software is used to simulate the cycles.


Author(s):  
Luca Bozzi ◽  
Enrico D’angelo

High turn-down operating of heavy-duty gas turbines in modern Combined Cycle Plants requires a highly efficient secondary air system to ensure the proper supply of cooling and sealing air. Thus, accurate performance prediction of secondary flows in the complete range of operating conditions is crucial. The paper gives an overview of the secondary air system of Ansaldo F-class AEx4.3A gas turbines. Focus of the work is a procedure to calculate the cooling flows, which allows investigating both the interaction between cooled rows and additional secondary flows (sealing and leakage air) and the influence on gas turbine performance. The procedure is based on a fluid-network solver modelling the engine secondary air system. Parametric curves implemented into the network model give the consumption of cooling air of blades and vanes. Performances of blade cooling systems based on different cooling technology are presented. Variations of secondary air flows in function of load and/or ambient conditions are discussed and justified. The effect of secondary air reduction is investigated in details showing the relationship between the position, along the gas path, of the upgrade and the increasing of engine performance. In particular, a section of the paper describes the application of a consistent and straightforward technique, based on an exergy analysis, to estimate the effect of major modifications to the air system on overall engine performance. A set of models for the different factors of cooling loss is presented and sample calculations are used to illustrate the splitting and magnitude of losses. Field data, referred to AE64.3A gas turbine, are used to calibrate the correlation method and to enhance the structure of the lumped-parameters network models.


Author(s):  
Tong Seop Kim ◽  
Sung Tack Ro

Performance of the heavy-duty gas turbine is analyzed with a special focus on the effect of turbine configuration. A general program is developed to fully represent the real component features by the characteristic models. The program is applied to simulate the performance of current heavy-duty gas turbines and its appropriateness for system analysis is verified. Meanwhile, the component parameters of real engines which describe the technology level are obtained. The effect of turbine parameters on the overall gas turbine performance is comparatively evaluated. A special emphasis is put on the analysis of the effect of number of turbine stages on the gas turbine performance and maximum power. Definite performance discrepancy due to the difference in the number of turbine stages is presented. It is found that number of turbine stages considerably affects the maximum gas flow and thermodynamic performance enhancement of the high-temperature advanced gas turbine is meaningful only when the mechanical constraint is relaxed.


2020 ◽  
Vol 142 (09) ◽  
pp. 56-57
Author(s):  
Lachlan J. Jardine ◽  
Robert J. Miller

Abstract For over 50 years, high-pressure gas turbine blades have been cooled using air bled from the compressor. This cooling results in very high rates of heat transfer, both within the fluid and within the blade, shown in figure 1. The heat transfer often occurs across large temperature differences and is thus highly irreversible. It is therefore surprising that little is understood about the effect of this heat transfer on turbine performance.


Sign in / Sign up

Export Citation Format

Share Document