| 1. |
- Colmenares, Fernando, et al.
(author)
-
Future Aero-Engines’ Optimisation for Minimal Fuel Burn
- 2008
-
In: <em><em>A</em></em>SME Turbo Expo 2008: Power for Land, Sea, and AirVolume 2: Controls, Diagnostics and Instrumentation; Cycle Innovations; Electric PowerBerlin, Germany, June 9–13, 2008. - 9780791843123 - 0791838242 ; , s. 411-416
-
Conference paper (peer-reviewed)abstract
- While aircraft environmental performance has been important since the beginnings of commercial aviation, continuously increasing passenger traffic and a rise in public awareness have made aircraft noise and emissions two of the most pressing issues hampering commercial aviation growth today. The air transportation for the new millennium will require revolutionary solutions to meeting public demand for improving safety, reliability, environmental compatibility, and affordability. The objective of this research is to assess the trade-off between operating costs and environmental requirements of the future aero engines for short range commercial aircrafts. This involves optimising the engines’ design point to minimise the block fuel and evaluating the economic and environmental impact. A high by-pass ratio turbofan engine with performance characteristics and technology from the year 2000 was set up as a baseline and compared to very high by-pass ratio turbofans. The results present a great potential benefit of the geared turbofan compared to high BPR one (baseline) to reduce cruise CO2 emissions and noise; however this may involve NOx penalties, that is an increase of 5.1% in comparison to the baseline. The CRTF engine seems to be, at least according to the simulations, a very promising solution in terms of environmental and economical performance. This is one on the series of work that would be carried out on the cycles being assessed in this paper (feasibility study). Further work on the specific technical issues — such as: technological implications — would be published when completed.
|
|
| 2. |
- Kyprianidis, Konstantinos G., et al.
(author)
-
EVA : A Tool for EnVironmental Assessment of Novel Propulsion Cycles
- 2008
-
In: <em><em></em></em>ASME Turbo Expo 2008: Power for Land, Sea, and AirVolume 2: Controls, Diagnostics and Instrumentation; Cycle Innovations; Electric PowerBerlin, Germany, June 9–13, 2008. - 9780791843123 - 0791838242 ; , s. 547-556
-
Conference paper (peer-reviewed)abstract
- This paper presents the development of a tool for EnVironmental Assessment (EVA) of novel propulsion cycles implementing the Technoeconomical Environmental and Risk Analysis (TERA) approach. For nearly 3 decades emissions certification and legislation has been mainly focused on the landing and take-off cycle. Exhaust emissions measurements of NOx, CO and unburned hydrocarbons are taken at Sea Level Static (SLS) conditions for 4 different power settings (idle, descent, approach and take-off) and are consecutively used for calculating the total emissions during the ICAO landing and take-off cycle. With the global warming issue becoming ever more important, stringent emissions legislation is soon to follow, focusing on all flight phases of an aircraft. Unfortunately, emissions measurements at altitude are either extremely expensive, as in the case of altitude test facility measurements, or unrealistic, as in the case of direct in flight measurements. Compensating for these difficulties, various existing methods can be used to estimate emissions at altitude from ground measurements. Such methods, however, are of limited help when it comes to assessing novel propulsion cycles or existing engine configurations with no SLS measurements available. The authors are proposing a simple and fast method for the calculation of SLS emissions, mainly implementing ICAO exhaust emissions data, corrections for combustor inlet conditions and technology factors. With the SLS emissions estimated, existing methods may be implemented to calculate emissions at altitude. The tool developed couples emissions predictions and environmental models together with engine and aircraft performance models in order to estimate the total emissions and Global Warming Potential of novel engine designs during all flight phases (i.e. the whole flight cycle). The engine performance module stands in the center of all information exchange. In this study, EVA and the described emissions prediction methodology have been used for the preliminary design analysis of three spool high bypass ratio turbofan engines. The capability of EVA to radically explore the design space available in novel engine configurations, while accounting for fuel burn and global warming potential during the whole flight cycle of an aircraft, is illustrated.
|
|
| 3. |
- Pascovici, Daniele S., et al.
(author)
-
Weibull Distributions Applied to Cost and Risk Analysis for Aero Engines
- 2008
-
In: <em><em>Proc. ASME</em>.</em> 43123; Volume 2: Controls, Diagnostics and Instrumentation; Cycle Innovations; Electric Power. GT2008-51060. - 9780791843123 - 0791838242 ; , s. 681-690
-
Conference paper (peer-reviewed)abstract
- This paper presents the use of Weibull formulation to the life analysis of different parts of the engine in order to estimate the cost of maintenance, the direct operating costs (DOC) and net present cost (NPC) of future type turbofan engines. The Weibull distribution is often used in the field of life data analysis due to its flexibility—it can mimic the behavior of other statistical distributions such as the normal and the exponential. The developed economic model is composed of three modules: a lifing module, an economic module and a risk module. The lifing module estimates the life of the high pressure turbine blades through the analysis of creep and fatigue over a full working cycle of the engine. The value of life calculated by the lifing is then taken as the baseline distribution to calculate the life of other important modules of the engine using the Weibull approach. Then the lower of the values of life of all the distributions is taken as time between overhaul (TBO), and used into the economic module calculations. The economic module uses the TBO together with the cost of labour and the cost of the engine (needed to determine the cost of spare parts) to estimate the cost of maintenance and DOC of the engine. In the present work five Weibull distributions are used for five important sources of interruption of the working life of the engine: Combustor, Life Limited Parts (LLP), High Pressure Compressor (HPC), General breakdowns and High Pressure Turbine (HPT). The risk analysis done in this work shows the impact of the breakdown of different parts of the engine on the NPC and DOC, the importance that each module of the engine has in its life, and how the application of the Weibull theory can help us in the risk assessment of future aero engines. A detailed explanation of the economic model is done in two other works (Pascovici et. al. [6] and Pascovici et. al. [7]), so in this paper only a general overview is done.
|
|
| 4. |
- Chernoray, Valery, 1975, et al.
(author)
-
Improving the accuracy of multihole probe measurements in velocity gradients
- 2008
-
In: 2008 ASME Turbo Expo; Berlin; Germany; 9 June 2008 through 13 June 2008. - 9780791843123 ; 2, s. 125-134
-
Conference paper (peer-reviewed)abstract
- This study describes an implementation and verification of an effective and reliable correction for the finite-size effects of pressure probes. A modified version of correction by Ligrani et al. (Exp. Fluids, vol. 7, 1989, p. 424) was used. It is shown that the correction procedure can be implemented in two steps as in Ligrani et al. or in a single step, either for probe pressures, or for velocity components. The latter correction method is found to have the best performance and studied in very detail. The effect of the correction in application to the highly three-dimensional flow downstream of the outlet guide vanes is scrutinized through detailed side-by-side comparison with corresponding cross hot-wire data. The influence of the correction on all three velocity components, flow streamlines and streamwise vorticity fields is thoroughly examined. Two flow cases with different incoming turbulence intensities are considered. The study demonstrates a very good efficiency and reliability of the correction, which lead to a significant improvement of the corrected velocity data. The improvement in crossflow velocity components has allowed correct description of the flow streamlines, and as a result, the secondary flow field structures were resolved more accurately. The considered correction does not affect the streamwise vorticity component, which is clarified as well. A very important fact is that the correction is not found to over-correct and distort the data, thus can be used safely. A very good performance of the correction for the finite-size effects of pressure probes presented in this study allows us to recommend it as a mandatory step in postprocessing procedures for multihole pressure probes.
|
|
| 5. |
- Fast, Magnus, et al.
(author)
-
Condition based maintenance of gas turbines using simulation data and artificial neural network: A demonstration of feasibility
- 2008
-
In: Proceedings of the ASME Turbo Expo 2008. - 0791838242 ; , s. 153-161
-
Conference paper (peer-reviewed)abstract
- Gas turbine maintenance is crucial due to high cost for the replacement of its components and associated loss of power during shutdown period. Conventional scheduled maintenance, based on equivalent operating hours, is not the best alternative as it can require unnecessary shut downs. Condition based maintenance is an attractive alternative as it decreases unnecessary shut downs and has other advantages for both the manufacturers and the plant owners. However, this has shown to be a complex/difficult task. A number of methods and approaches have been presented to develop condition monitoring tools during the past decade. Condition monitoring tools can e.g. be developed by means of training artificial neural networks (ANN) with historical operational data. Such tools can be used for online gas turbine performance prediction where input data from the plant is fed directly to the trained ANN models. The predicted outputs from the models are compared with corresponding measurements and possible deviations are evaluated. With this method both recoverable degradation, caused by fouling, and irrecoverable degradation, caused by wear, can be detected and hence both compressor wash and overhaul periods optimized. However, non-availability of operational data at the beginning of the gas turbine operation may cause problems for the development of ANN based condition monitoring tools. Simulation data, on the other hand, may be generated by using a manufacturer’s engine design program. This data can be used for training artificial neural networks to overcome the problem of non-availability of operational data. ANN models trained with simulation data could be used to monitor the engine from the very beginning of its operation. A demonstration case using a Siemens gas turbine has been shown for this proposed method by comparing two ANN models, one trained with operational data and the other with simulation data. For the comparison an arbitrary section of operational data was used to produce predictions from both models, whereupon these were plotted with corresponding measured data. The comparison shows that the trends are very similar but the parameter values for the measured and the simulated data are shifted by a constant. Using this knowledge, one can provide an ANN based engine monitoring tool that could be adjusted to a certain engine using engine performance test data. The study shows promising results and motivates further investigations in this field.
|
|
