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.

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.

Effects of Anti-Icing System Operation on Gas Turbine Performance and Monitoring

2001 ◽  
Author(s):  
K. Mathioudakis ◽  
A. Tsalavoutas
Keyword(s):  
Gas Turbine ◽  
Engine Performance ◽  
Performance Model ◽  
False Alarms ◽  
System Operation ◽  
Diagnostic Ability ◽  
Engine Model ◽  
On Line ◽  
Industrial Gas Turbine ◽  
Engine Condition

The effect of operation of compressor bleed anti-icing on the performance of an industrial gas turbine is analysed. The effect of putting this system in operation is first qualitatively discussed, while the changes on various performance parameters are derived by using a computer engine performance model. The main point of the paper is the study of the effect of anti-icing system operation on parameters used for engine condition monitoring. It is shown that operation of the anti-icing system causes an apparent modification of such parameters, which may reduce the diagnostic ability of an on-line monitoring system and produce false alarms. It is shown that by incorporating the effect of anti-icing system operation into a diagnostic engine model, such problems can be avoided and the diagnostic ability of the system is not influenced by anti-icing activation. The analysis presented is substantiated through experimental data from a twin shaft gas turbine operating in the field.

Effect of Manufacturing Variability on Turbine Engine Performance: A Probabilistic Study

2013 ◽  
Author(s):  
Michael Gorelik ◽  
Jacob Obayomi ◽  
Jack Slovisky ◽  
Dan Frias ◽  
Howie Swanson ◽  
...  
Keyword(s):  
Performance Metrics ◽  
Model Development ◽  
Engine Performance ◽  
Performance Model ◽  
Probabilistic Methods ◽  
System Level ◽  
Turbine Engine ◽  
Probabilistic Study ◽  
Blade Geometry

While turbine engine Original Equipment Manufacturers (OEMs) accumulated significant experience in the application of probabilistic methods (PM) and uncertainty quantification (UQ) methods to specific technical disciplines and engine components, experience with system-level PM applications has been limited. To demonstrate the feasibility and benefits of an integrated PM-based system, a numerical case study has been developed around the Honeywell turbine engine application. The case study uses experimental observations of engine performance such as horsepower and fuel flow from a population of engines. Due to manufacturing variability, there are unit-to-unit and supplier-to-supplier variations in compressor blade geometry. Blade inspection data are available for the characterization of these geometric variations, and CFD analysis can be linked to the engine performance model, so that the effect of blade geometry variation on system-level performance characteristics can be quantified. Other elements of the case study included the use of engine performance and blade geometry data to perform Bayesian updating of the model inputs, such as efficiency adders and turbine tip clearances. A probabilistic engine performance model was developed, system-level sensitivity analysis performed, and the predicted distribution of engine performance metrics was calibrated against the observed distributions. This paper describes the model development approach and key simulation results. The benefits of using PM and UQ methods in the system-level framework are discussed. This case study was developed under Defense Advanced Research Projects Agency (DARPA) funding which is gratefully acknowledged.

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.

Development and Integration of Rain Ingestion Effects in Engine Performance Simulations

2014 ◽  
Vol 137 (4) ◽  
Author(s):  
I. Roumeliotis ◽  
A. Alexiou ◽  
N. Aretakis ◽  
G. Sieros ◽  
K. Mathioudakis
Keyword(s):  
Engine Performance ◽  
Velocity Slip ◽  
Droplet Surface ◽  
Performance Model ◽  
Droplet Breakup ◽  
Test Case ◽  
Case Scenario ◽  
Worst Case ◽  
Engine Model ◽  
Component Models

Rain ingestion can significantly affect the performance and operability of gas turbine aero-engines. In order to study and understand rain ingestion phenomena at engine level, a performance model is required that integrates component models capable of simulating the physics of rain ingestion. The current work provides, for the first time in the open literature, information about the setup of a mixed-fidelity engine model suitable for rain ingestion simulation and corresponding overall engine performance results. Such a model can initially support an analysis of rain ingestion during the predesign phase of engine development. Once components and engine models are validated and calibrated versus experimental data, they can then be used to support certification tests, the extrapolation of ground test results to altitude conditions, the evaluation of control or engine hardware improvements and eventually the investigation of in-flight events. In the present paper, component models of various levels of fidelity are first described. These models account for the scoop effect at engine inlet, the fan effect and the effects of water presence in the operation and performance of the compressors and the combustor. Phenomena such as velocity slip between the liquid and gaseous phases, droplet breakup, droplet–surface interaction, droplet and film evaporation as well as compressor stages rematching due to evaporation are included in the calculations. Water ingestion influences the operation of the components and their matching, so in order to simulate rain ingestion at engine level, a suitable multifidelity engine model has been developed in the Proosis simulation platform. The engine model's architecture is discussed, and a generic high bypass turbofan is selected as a demonstration test case engine. The analysis of rain ingestion effects on engine performance and operability is performed for the worst case scenario, with respect to the water quantity entering the engine. The results indicate that rain ingestion has a strong negative effect on high-pressure compressor surge margin, fuel consumption, and combustor efficiency, while more than half of the water entering the core is expected to remain unevaporated and reach the combustor in the form of film.

Comparison and Synthesis of Performance and Aerodynamic Modeling of a Pass-Off Turbofan Engine Test Cell

2015 ◽  
Author(s):  
Martin Marx ◽  
Michael Kotulla ◽  
André Kando ◽  
Stephan Staudacher
Keyword(s):  
Research Effort ◽  
Engine Performance ◽  
Cell System ◽  
Performance Model ◽  
Test Cell ◽  
Test Facility ◽  
Engine Test ◽  
Combined System ◽  
Installation Effects ◽  
Engine Testing

To ensure the quality standards in engine testing, a growing research effort is put into the modeling of full engine test cell systems. A detailed understanding of the performance of the combined system, engine and test cell, is necessary e.g. to assess test cell modifications or to identify the influence of test cell installation effects on engine performance. This study aims to give solutions on how such a combined engine and test cell system can be effectively modeled and validated in the light of maximized test cell observability with minimum instrumentation and computational requirements. An aero-thermodynamic performance model and a CFD model are created for the Fan-Engine Pass-Off Test Facility at MTU Maintenance Berlin-Brandenburg GmbH, representing a W-shape configuration, indoor Fan-Engine test cell. Both models are adjusted and validated against each other and against test cell instrumentation. A fast-computing performance model is delivering global parameters, whereas a highly-detailed aerodynamic simulation is established for modeling component characteristics. A multi-disciplinary synthesis of both approaches can be used to optimize each of the specific models by calibration, optimized boundary conditions etc. This will result in optimized models, which, in combination, can be used to assess the respective design and operational requirements.

Atlantic, Pacific, and world-wide features in English-lexicon contact languages

2001 ◽  
Vol 22 (2) ◽  
pp. 157-208 ◽  
Author(s):  
Philip Baker ◽  
Magnus Huber
Keyword(s):  
World Wide ◽  
Statistical Feature ◽  
The Pacific ◽  
Geographical Regions ◽  
Feature Based ◽  
The Individual ◽  
Shed Light

This article analyzes the earliest known attestations of 302 lexical, functional, and grammatical features in 13 English-lexicon contact languages in the Atlantic and the Pacific. The main aims are (i) to shed light on the historical relationships between the individual varieties, (ii) to learn about the mechanisms at work in their genesis and development, and (iii) to examine the significance of features common to both geographical regions. Overall, our intention is to demonstrate that a statistical feature-based approach as proposed here can yield valuable insights into the development and interrelationships between Pidgins and Creoles.

Analysis of Effect of Advanced Technique Configurations on Overall Performance of High Bypass Turbofan Engine

2014 ◽  
Author(s):  
Liu Jian Jun
Keyword(s):  
Air Flow ◽  
Engine Performance ◽  
Performance Model ◽  
Direct Drive ◽  
Nozzle Throat ◽  
Advanced Technique ◽  
Turbofan Engine ◽  
Overall Performance ◽  
Cooling Air Flow ◽  
Cooling Air

An analytical study was undertaken using the performance model of a two spool direct drive high BPR 300kN thrust turbofan engine, to investigate the effects of advanced configurations on overall engine performance. These include variable bypass nozzle, variable cooling air flow and more electric technique. For variable bypass nozzle, analysis on performance of outer fan at different conditions indicates that different operating points cannot meet optimal performance at the same time if the bypass nozzle area kept a constant. By changing bypass nozzle throat area at different states, outer fan operating point moves to the location where airflow and efficiency are more appropriate, and have enough margin away from surge line. As a result, the range of variable area of bypass nozzle throat is determined which ensures engine having a low SFC and adequate stability. For variable cooling airflow, configuration of turbine cooling air flow extraction and methodology for obtaining change of cooling airflow are investigated. Then, base on temperature analysis of turbine vane and blade and resistance of cooling airflow, reduction of cooling airflow is determined. Finally, using performance model which considering effect of cooling air flow on work and efficiency of turbine, variable cooling airflow effect on overall performance is analyzed. For more electric technique, the main characteristic is to use power off-take instead of overboard air extraction. Power off-take and air extraction effect on overall performance of high bypass turbofan engine is compared. Investigation demonstrates that power offtake will have less SFC.

Development and Validation of an On-Wing Engine Thrust Measurement System

2017 ◽  
Author(s):  
Marc Bauer ◽  
Jens Friedrichs ◽  
Detlev Wulff ◽  
Christian Werner-Spatz
Keyword(s):  
Measurement System ◽  
Standard Procedure ◽  
Flight Test ◽  
Engine Thrust ◽  
Thrust Measurement ◽  
Ground Test ◽  
Engine Maintenance ◽  
The Cost ◽  
Development And Validation ◽  
Engine Condition

Maintenance on aircraft engines is usually performed on an on-condition basis. Monitoring the engine condition during operation is an important prerequisite to provide efficient maintenance. Engine Condition Monitoring (ECM) has thus become a standard procedure during operation. One of the most important parameters, the engine thrust, is not directly measured, however, and can therefore not be monitored, which makes it difficult to distinguish whether deteriorating trends e.g. in fuel comsumption must be attributed to the engine (e.g. due to thermodynamic wear) or to the aircraft (e.g. due to increased drag). Being able to make this distinction would improve troubleshooting and maintenance planning and thus help to reduce the cost of ownership of an aircraft. As part of the research project APOSEM (Advanced Prediction of Severity effects on Engine Maintenance), Lufthansa Technik (LHT) and the Institute of Jet Propulsion and Turbomachinery of Technische Universität Braunschweig develop a method for direct measurement of engine thrust during the operation. In this paper, the design process of the On-Wing (OW) Measurement System is presented, including the validation in labratory tests, the mechanical and thermal calibration as well as the final ground test during an engine test run at LHT test cell and the work on the flight test certification.

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