Probabilistic Engine Maintenance Modeling for Varying Environmental and Operating Conditions

2010 ◽  
Author(s):  
Matthias Mu¨ller ◽  
Stephan Staudacher ◽  
Winfried-Hagen Friedl ◽  
Rene´ Ko¨hler ◽  
Matthias Weißschuh
Keyword(s):  
Engine Performance ◽  
Distribution Functions ◽  
Performance Model ◽  
Operating Conditions ◽  
Maintenance Cost ◽  
Engine Operation ◽  
Performance Deterioration ◽  
And Performance ◽  
The Individual ◽  
Engine Maintenance

The maintenance and reliability of aircraft engines is strongly influenced by the environmental and operating conditions they are subjected to in service. A probabilistic tool has been developed to predict shop visit arisings and respective maintenance workscope that depends on these factors. The tool contains a performance model of the engine and a number of physics-based damage mechanisms (at piece part level). The performance model includes variation of performance relevant parameters due to production scatter and delivers the conditions to determine the deterioration of the individual parts. Shop visit maintenance is modeled as a result of limitations to engine operation, e.g. reaching TGT limit, or mechanical deterioration. The influence of maintenance actions on engine performance is determined on component basis. The maintenance strategy can consist of proactive and reactive maintenance elements. The decision of repair or replacement of any single part is implemented through a sum of different logic rules in the model. The loading capacity scatter depends on the engine type and is operator independent. It is represented via data-driven distribution functions, in which the probabilities of failure, repair and replacement for each part are specified depending on the number of reference flight cycles. The loading variation is considered through a physics-based cycle weighting. The developed tool runs a Monte Carlo simulation in which a fleet of engines is modeled through their respective lifetime of maintenance and performance deterioration. Using an example it is shown that the model can describe the effects of varying environmental and operating conditions on part damage, and therefore engine maintenance cost and reliability.

Modelling and Assessment of Compressor Faults on Marine Gas Turbines

2012 ◽  
Author(s):  
I. Roumeliotis ◽  
N. Aretakis ◽  
K. Mathioudakis ◽  
E. A. Yfantis
Keyword(s):  
Gas Turbines ◽  
Engine Performance ◽  
Performance Model ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Maximum Speed ◽  
Performance Modelling ◽  
Engine Operation ◽  
Marine Propulsion ◽  
And Performance

Any prime mover exhibits the effects of wear and tear over time, especially when operating in a hostile environment. Marine gas turbines operation in the hostile marine environment results in the degradation of their performance characteristics. A method for predicting the effects of common compressor degradation mechanisms on the engine operation and performance by exploiting the “zooming” feature of current performance modelling techniques is presented. Specifically a 0D engine performance model is coupled with a higher fidelity compressor model which is based on the “stage stacking” method. In this way the compressor faults can be simulated in a physical meaningful way and the overall engine performance and off design operation of a faulty engine can be predicted. The method is applied to the case of a twin shaft engine, a configuration that is commonly used for marine propulsion. In the case of marine propulsion the operating profile includes a large portion of off-design operation, thus in order to assess the engine’s faults effects, the engine operation should be examined with respect to the marine vessel’s operation. For this reason, the engine performance model is coupled to a marine vessel’s mission model that evaluates the prime mover’s operating conditions. In this way the effect of a faulty engine on vessels’ mission parameters like overall fuel consumption, maximum speed, pollutant emissions and mission duration can be quantified.

Evaluation of Total Engine Performance Degradation Based on Modular Efficiencies

2011 ◽  
Author(s):  
Carsten Ebmeyer ◽  
Jens Friedrichs ◽  
Tobias Wensky ◽  
Uwe Zachau
Keyword(s):  
Performance Status ◽  
Engine Performance ◽  
Performance Degradation ◽  
Performance Model ◽  
Maintenance Program ◽  
Geographical Regions ◽  
Deterioration Mechanism ◽  
The Individual ◽  
Engine Maintenance ◽  
Engine Condition

The current maintenance and overhaul of large civil jet engines is completely based on-condition and is widely customized to the individual requirements of the operation. Therefore, a very important factor for an effective and economic engine maintenance program is the investigation and appreciation of the current engine condition, as well as its individual deterioration mechanism. This paper is introducing a method to analyze the engine performance deterioration between two typical off-wing maintenance events (shop visits) so as to draw conclusions for maintenance planning and operation. In order to perform a precise evaluation the performance analysis is conducted on a modular level. Therefore the engine is divided into the following major modules: FAN, LPC, HPC, combustor, HPT, LPT and exhaust nozzle. The basis for the evaluation is the overhauled engine condition after a shop visit (pass-off test run) and the deteriorated engine condition after operation (incoming test run). These two points in the engine life cycle provide specific engine conditions that are to be analyzed by scientific and commercial software, and combined with a self-developed engine performance model in order to obtain the desired results: The individual engine deterioration during operation demonstrated by the differences of the modular performance between incoming test run and the last pass-off test run. In addition, to ensure the continuous monitoring of the performance status between the two test runs, it is important to analyze the “on-wing operation”. This is done using MTU’s Engine Trend Monitoring (ETM) system, which generates performance data based on the available in-flight data. In this paper an analysis example is used to present the analytic method and the obtained results. Reasons of deterioration are evaluated separately in reference to different environmental influences from specific geographical regions. In summary this paper introduces a solution to track the total engine performance based on modular evaluation values, starting at improvements for pass-off and incoming test runs as well as performance degradation during the on-wing time.

Instructing the Principles of Gas Turbine Performance Monitoring and Diagnostics by Means of Interactive Computer Models

2000 ◽  
Author(s):  
K. Mathioudakis ◽  
A. Stamatis ◽  
A. Tsalavoutas ◽  
N. Aretakis
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Performance Monitoring ◽  
Measurement Data ◽  
Engine Performance ◽  
Performance Model ◽  
Operating Conditions ◽  
Engine Operation ◽  
Turbine Performance ◽  
Engine Components

The paper discusses how the principles employed for monitoring the performance of gas turbines in industrial duty can be explained by using suitable Gas Turbine performance models. A particular performance model that can be used for educational purposes is presented. The model allows the presentation of basic rules of gas turbine engine behavior and helps understanding different aspects of its operation. It is equipped with a graphics interface, so it can present engine operating point data in a number of different ways: operating line, operating points of the components, variation of particular quantities with operating conditions etc. Its novel feature, compared to existing simulation programs, is that it can be used for studying cases of faulty engine operation. Faults can be implanted into different engine components and their impact on engine performance studied. The notion of fault signatures on measured quantities is clearly demonstrated. On the other hand, the model has a diagnostic capability, allowing the introduction of measurement data from faulty engines and providing a diagnosis, namely a picture of how the performance of engine components has deviated from nominal condition, and how this information gives the possibility for fault identification.

Probabilistic Engine Performance Scatter and Deterioration Modeling

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Stefan Spieler ◽  
Stephan Staudacher ◽  
Roland Fiola ◽  
Peter Sahm ◽  
Matthias Weißschuh
Keyword(s):  
Test Data ◽  
Probabilistic Approach ◽  
Engine Performance ◽  
Aircraft Engine ◽  
Operating Conditions ◽  
Performance Data ◽  
Maintenance Cost ◽  
Performance Parameters ◽  
Engine Operation ◽  
The Impact

The change of performance parameters over time due to engine deterioration and production scatter plays an important role to ensure safe and economical engine operation. A tool has been developed which is able to model production scatter and engine deterioration on the basis of elementary changes of numerous construction features. In order to consider the characteristics of an engine fleet as well as random environmental influences, a probabilistic approach using Monte Carlo simulation (MCS) was chosen. To quantify the impact of feature deviations on performance relevant metrics, nonlinear sensitivity functions are used to obtain scalars and offsets on turbomachinery maps, which reflect module behavior during operation. Probability density functions (PDFs) of user-defined performance parameters of an engine fleet are then calculated by performing a MCS in a performance synthesis program. For the validation of the developed methodology pass-off test data, endurance engine test data, as well as data from engine maintenance, incoming tests have been used. For this purpose, measured engine fleet performance data have been corrected by statistically eliminating the influence of measuring errors. The validation process showed the model’s ability to predict more than 90% of the measured performance variance. Furthermore, predicted performance trends correspond well to performance data from engines in operation. Two model enhancements are presented, the first of which is intended for maintenance cost prediction. It is able to generate PDFs of failure times for different features. The second enhancement correlates feature change and operating conditions and thus connects airline operation and maintenance costs. Subsequently, it is shown that the model developed is a powerful tool to assist in aircraft engine design and production processes, thanks to its ability to identify and quantitatively assess main drivers for performance variance and trends.

Probabilistic Engine Performance Scatter and Deterioration Modeling

2007 ◽  
Author(s):  
Stefan Spieler ◽  
Stephan Staudacher ◽  
Roland Fiola ◽  
Peter Sahm ◽  
Matthias Weißschuh
Keyword(s):  
Test Data ◽  
Probabilistic Approach ◽  
Engine Performance ◽  
Aircraft Engine ◽  
Operating Conditions ◽  
Performance Data ◽  
Maintenance Cost ◽  
Performance Parameters ◽  
Engine Operation ◽  
The Impact

The change of performance parameters over time due to engine deterioration and production scatter plays an important role to ensure safe and economical engine operation. A tool has been developed which is able to model production scatter and engine deterioration on the basis of elementary changes of numerous construction features. In order to consider the characteristics of an engine fleet as well as random environmental influences, a probabilistic approach using Monte Carlo Simulation (MCS) was chosen. To quantify the impact of feature deviations on performance relevant metrics, non-linear sensitivity functions are used to obtain scalars and offsets on turbomachinery maps which reflect module behavior during operation. Probability density functions (PDFs) of user-defined performance parameters of an engine fleet are then calculated by performing an MCS in a performance synthesis program. For the validation of the developed methodology pass-off test data, endurance engine test data, as well as data from engine maintenance incoming tests have been used. For this purpose, measured engine fleet performance data have been corrected by statistically eliminating the influence of measuring errors. The validation process showed the model’s ability to predict more than 90% of the measured performance variance. Furthermore, predicted performance trends correspond well to performance data from engines in operation. Two model enhancements are presented, the first of which is intended for maintenance cost prediction. It is able to generate PDFs of failure times for different features. The second enhancement correlates feature change and operating conditions and thus connects airline operation and maintenance costs. Subsequently, it is shown that the model developed is a powerful tool to assist in aircraft engine design and production processes thanks to its ability to identify and quantitatively assess main drivers for performance variance and trends.

scholarly journals CFD Study of Nozzle Configurations for Ultra High Bypass Engines

1993 ◽  
Author(s):  
H. Zimmermann ◽  
R. Gumucio ◽  
K. Katheder ◽  
A. Jula
Keyword(s):  
Engine Performance ◽  
Operating Conditions ◽  
Aerodynamic Design ◽  
Thrust Coefficient ◽  
Optimum Range ◽  
Installation Effects ◽  
Wide Range ◽  
And Performance ◽  
Aircraft Aerodynamics ◽  
Bypass Ratio

Performance and aerodynamic aspects of ultra-high bypass ratio ducted engines have been investigated with an emphasis on nozzle aerodynamics. The interference with aircraft aerodynamics could not be covered. Numerical methods were used for aerodynamic investigations of geometrically different aft end configurations for bypass ratios between 12 and 18, this is the optimum range for long missions which will be important for future civil engine applications. Results are presented for a wide range of operating conditions and effects on engine performance are discussed. The limitations for higher bypass ratios than 12 to 18 do not come from nozzle aerodynamics but from installation effects. It is shown that using CFD and performance calculations an improved aerodynamic design can be achieved. Based on existing correlations, for thrust and mass-flow, or using aerodynamic tailoring by CFD and including performance investigations, it is possible to increase the thrust coefficient up to 1%.

Design and Performance of a Controlled Turbocharging System on Marine Diesel Engines

2006 ◽  
Author(s):  
Ioannis Vlaskos ◽  
Ennio Codan ◽  
Nikolaos Alexandrakis ◽  
George Papalambrou ◽  
Marios Ioannou ◽  
...  
Keyword(s):  
Steady State ◽  
Engine Performance ◽  
Operating Conditions ◽  
Electric Actuator ◽  
Engine Simulation ◽  
Engine Control System ◽  
Turbocharging System ◽  
Compressor Impeller ◽  
Marine Diesel ◽  
And Performance

The paper describes the design process for a controlled pulse turbocharging system (CPT) on a 5 cylinder 4-stroke marine engine and highlights the potential for improved engine performance as well as reduced smoke emissions under steady state and transient operating conditions, as offered by the following technologies: • controlled pulse turbocharging, • high pressure air injection onto the compressor impeller as well as into the air receiver, and • an electronic engine control system, including a hydraulic powered electric actuator. Calibrated engine simulation computer models based on the results of tests performed on the engine in its baseline configuration were used to design the CPT components. Various engine tests with CPT under steady state and transient operating conditions show the engine optimization process and how the above-mentioned technologies benefit engine behavior in both generator and propeller law operation.

Adaptation Application to Engine Modelling

2007 ◽  
Author(s):  
Jude Iyinbor
Keyword(s):  
Measurement Data ◽  
Engine Performance ◽  
Performance Model ◽  
Operating Conditions ◽  
Adaptation Process ◽  
Design Point ◽  
Component Map ◽  
Important Measurement ◽  
Unknown Component ◽  
Selection Of

The optimisation of engine performance by predictive means can help save cost and reduce environmental pollution. This can be achieved by developing a performance model which depicts the operating conditions of a given engine. Such models can also be used for diagnostic and prognostic purposes. Creating such models requires a method that can cope with the lack of component parameters and some important measurement data. This kind of method is said to be adaptive since it predicts unknown component parameters that match available target measurement data. In this paper an industrial aeroderivative gas turbine has been modelled at design and off-design points using an adaptation approach. At design point, a sensitivity analysis has been used to evaluate the relationships between the available target performance parameters and the unknown component parameters. This ensured the proper selection of parameters for the adaptation process which led to a minimisation of the adaptation error and a comprehensive prediction of the unknown component and available target parameters. At off-design point, the adaptation process predicted component map scaling factors necessary to match available off-design point performance data.

Military Engine Response to Compressor Inlet Stratified Pressure Distortion by an Integrated CFD Analysis

2006 ◽  
Author(s):  
Leonardo Melloni ◽  
Petros Kotsiopoulos ◽  
Anthony Jackson ◽  
Vassilios Pachidis ◽  
Pericles Pilidis
Keyword(s):  
Engine Performance ◽  
Low Pressure ◽  
Operating Conditions ◽  
High Fidelity ◽  
Inlet Flow ◽  
Performance Simulation ◽  
Simulation Strategy ◽  
Compressor Inlet ◽  
And Performance ◽  
Pressure Compressor

Especially in aircraft applications, the inlet flow is quite often non uniform resulting in severe changes in compressor performance and hence, engine performance. The magnitude of this phenomenon can be amplified in military engines due to the complex shape of intake ducts and the extreme flight conditions. The usual approach to engine performance simulation is based on non-dimensional maps for compressors and turbines and assumes uniform flow characteristics throughout the engine. In the context of the whole engine performance, component-level, complex physical processes, such as compressor inlet flow distortion, can not be captured and analyzed. This work adopts a simulation strategy that allows the performance characteristics of an engine component, resolved from a detailed, high-fidelity analysis, to be transferred to an engine system analysis carried out at a lower level of fidelity. The methodology described in this paper utilizes an object-oriented, zero-dimensional gas turbine modeling and performance simulation system and a high-fidelity, three-dimensional, computational fluid dynamics (CFD), low-pressure compressor model. The CFD model is based on the overall geometry and performance of the low-pressure compressor of a modern, two-spool, low by-pass ratio (LBR) military turbofan engine and is subjected to both clean and distorted inlet flows. The analysis involves the generation of two characteristic maps for the first stage of the LP compressor from CFD simulations that account for a range of operating conditions and power settings with a uniform and a distorted inlet flow. The same simulation strategy could be adopted for other engine components such as the intake or the high-pressure compressor and for different magnitudes and types of distortion (i.e. radial, circumferential). By integrating the CFD-generated maps, into the 0-D engine analysis system, this paper presents a relative comparison between the ‘uniform-inlet’ engine performance (baseline compressor stage map) and the engine performance obtained after using the map accounting for a typical extent of stratified inlet distortion. The analysis carried out by this study, demonstrates relative changes in the simulated engine performance larger than 1%.

Assessing Double Injection and Intake Air Temperature Effects on Gasoline HCCI Engine Performance and Emissions Using Fully-Automated Experiments and Micro-Genetic Algorithms

2002 ◽  
Author(s):  
Mustafa Canakci ◽  
Eric Hruby ◽  
Rolf D. Reitz
Keyword(s):  
Air Temperature ◽  
Gasoline Engine ◽  
Engine Performance ◽  
Operating Conditions ◽  
Spray Angle ◽  
Injection Timing ◽  
Engine Operation ◽  
Double Injection ◽  
Performance And Emissions ◽  
Engine Performance And Emissions

Homogeneous charge compression ignition (HCCI) is receiving attention as a new low emission engine concept. Little is known about the optimal operating conditions for this engine operation mode. Combustion at homogeneous, low equivalence ratio conditions results in modest temperature combustion products, containing very low concentrations of NOx and PM as well as providing high thermal efficiency. However, this combustion mode can produce higher HC and CO emissions than those of conventional engines. An electronically controlled Caterpillar single-cylinder oil test engine (SCOTE), originally designed for heavy-duty diesel applications, was converted to a HCCI direct-injection gasoline engine. The engine features an electronically controlled low-pressure common rail injector with a 60°-spray angle that is capable of multiple injections. The use of double injection was explored for emission control, and the engine was optimized using fully-automated experiments and a micro-genetic algorithm (μGA) optimization code. The variables changed during the optimization include the intake air temperature, start of injection timing, and split injection parameters (percent mass of the fuel in each injection, dwell between the pulses). The engine performance and emissions were determined at 700 rev/min with a constant fuel flow rate at 10 MPa fuel injection pressure. The results show that significant emissions reductions are possible with the use of optimal injection strategies.

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