Stochastic field models for jet engine component responses

Author(s):  
Dan Ghiocel
2000 ◽  
Author(s):  
Dan M. Ghiocel

Abstract The paper addresses significant aspects of stochastic modeling for jet engine component life prediction. Probabilistic life prediction for gas turbine engine components represents a very difficult engineering problem involving stochastic modeling of multiple, complex random phenomena. A key aspect for developing a probabilistic life prediction tool is to incorporate, and to be open to modeling advances related to dynamic complex random phenomena, including space-time random variabilities of mission environment and material parameters, aero-elastic interactions, friction at contact interfaces, multi-site fatigue, progressive damage mechanism, including loading interactions, etc.. The paper addresses the main aspects involved in stochastic modeling of component fatigue life prediction for jet engine rotating components, specifically fan blades. The paper highlights the need of the use of stochastic process and field models for including space-time varying random aspects. Mission speed profiles produced by pilot’s random maneuvers are modeled by pulse non-Gaussian stochastic processes. These pulse processes are approximated using linear recursive models when the cluster effects are not significant. A more general approach, useful when cluster effects are significant, based on a combination of two pulse processes is used. Aero-pressure distribution on blade as well as blade surface geometry deviations due to manufacturing are idealized by using factorable stochastic field models. Also, stochastic field models are used for modeling strain-life and damage accumulation curves. Stochastic damage accumulation models are based on randomized stress-dependent models (nonlinear damage rule models). The paper also addresses mathematical modeling of stochastic nonlinear responses in multidimensional parameter spaces. Stochastic response surface techniques based on factorable stochastic fields or optimum stochastic models are suggested. An illustrative example of a jet engine blade is used for discussion and to show the consequences of different modeling assumptions.


2019 ◽  
Vol 25 (S2) ◽  
pp. 2534-2535
Author(s):  
HM Gardner ◽  
A Radecka ◽  
D Rugg ◽  
DEJ Armstrong ◽  
MP Moody ◽  
...  

2016 ◽  
Vol 138 (09) ◽  
pp. 76-77
Author(s):  
Lee S. Langston

This article throws light on details of jet engine thrust. The momentum flux of the engine exiting flow is greater than that which entered, brought about by the addition of the energy input from combusted fuel, and giving rise to engine thrust. Thrust arises from pressure and frictional forces on these surfaces, e.g., blades, vanes, endwalls, ducts, etc. This interior force view of thrust is easy to visualize but quite another thing to actually measure. In doing research on secondary flow in gas turbine passages, researchers have measured both steady-state momentum changes and surface forces, in the much simpler case of a turbine blade cascade. The thrust values for each component in the Rolls-Royce single spool engine have been shown in this paper. It has been noted that from the compressor, gas path flow enters the engine case diffuser, where a pressure gain produces another component of forward thrust of 2,186 lbt. Newton’s second law of motion allows us to examine engine component behavior that exhibits both forward and rearward propelling forces, which results in the net thrust our airline passengers have purchased.


Author(s):  
M. Lichtsinder ◽  
Y. Levy

Engine component and transducer degradation/fault diagnosis, are analyzed. The analysis is performed using an aero-thermodynamic nonlinear inverse jet-engine model while using data acquired during transient engine operation. A shortened inverse jet-engine model (without one or more engine component maps) was recently proposed by the authors for real-time simulations and for fast evaluation of engine component maps. The algorithm for the engine component’s fault diagnosis is significantly simplified using shortened inverse engine models. A diagnostic example of combined faults of a single transducer and a single engine component for a single spool jet engine is described using different combinations of shortened inverse jet engine models. In the present paper it is assumed that only a single transducer (out of the seven transducers) and /or a single engine component (compressor or turbine) fault could be present in the engine at a given time.


2006 ◽  
Vol 129 (4) ◽  
pp. 970-976 ◽  
Author(s):  
C. Romessis ◽  
Ph. Kamboukos ◽  
K. Mathioudakis

A method is proposed to support least square type of methods for deriving health parameters from a small number of independent gas path measurements. The method derives statistical information using sets of solutions derived from a number of data records, to produce sets of candidate solutions with a lesser number of parameters. These sets can then be processed to derive an accurate component fault diagnosis. It could thus be classified as a new type of "concentrator" approach, which is shown to be more effective than previously existing schemes. The method's effectiveness is demonstrated by application to a number of typical jet engine component faults.


1975 ◽  
Vol 12 (4) ◽  
pp. 293-295 ◽  
Author(s):  
Michael L. Parin ◽  
David I. G. Jones

Author(s):  
Dan M. Ghiocel

The paper proposes a refined stochastic fault classifier for jet engine vibration diagnostic based on advanced stochastic concepts. The statistical data to be analyzed are the spectrum profiles of vibration measured at different locations in the engine. The statistical spectrum profiles are idealized by non-homogeneous stochastic fields with non-Gaussian probability distributions. The proposed stochastic classifier is based on the decomposition of the statistical correlation matrix of spectrum profiles using a Karhunen-Loeve (KL) expansion. Two stochastic classifiers are proposed, namely a “global” and a “specific” fault classifier. The “global” KL classifier, which is a scalar quantity, is an efficient anomaly/novelty detection tool for identifying incipient fault diagnosis with small amplitude fluctuations. The “specific” KL classifier, which is a vector quantity, is a refined diagnostic tool for identifying the engine malfunction causes. An illustrative example of a turbofan engine is included.


2020 ◽  
Vol 6 ◽  
Author(s):  
Michael Poznic ◽  
Martin Stacey ◽  
Rafaela Hillerbrand ◽  
Claudia Eckert

Designing complex products involves working with uncertainties as the product, the requirements and the environment in which it is used co-evolve, and designers and external stakeholders make decisions that affect the evolving design. Rather than being held back by uncertainty, designers work, cooperate and communicate with each other notwithstanding these uncertainties by making assumptions to carry out their own tasks. To explain this, the paper proposes an adaptation of Kendall Walton’s make-believe theory to conceptualise designing as playing games of make-believe by inferring what is required and imagining what is possible given the current set of assumptions and decisions, while knowing these are subject to change. What one is allowed and encouraged to imagine, conclude or propose is governed by socially agreed rules and constraints. The paper uses jet engine component design as an example to illustrate how different design teams make assumptions at the beginning of design activities and negotiate what can and cannot be done with the design. This often involves iteration – repeating activities under revised sets of assumptions. As assumptions are collectively revised, they become part of a new game of make-believe in the sense that there is social agreement that the decisions constitute part of the constraints that govern what can legitimately be inferred about the design or added to it.


1997 ◽  
Vol 13 (5) ◽  
pp. 665-674 ◽  
Author(s):  
G. Sieros ◽  
A. Stamatis ◽  
K. Mathioudakis

Author(s):  
Benjamin Gal-Or

Abstract, jet-engine researchers, designers and operators should follow changing uses of small and large jet engines, especially those anticipated to be used by/in the next generation,In addition, some diminishing returns from isolated, non-integrating, jet-engine component studies, vs. relevant, supersonic, shock waves control inThe central roles of the jet engine as primary or backup flight controller also constitute key relevant issues, especially under post stall conditions involving induced engine-stress while participating in crash prevention or minimal path-time maneuvers to target. [are anticipated to overcome US legislation red-tape that obstructs JES-add-on-emergency-kits-use. [


Sign in / Sign up

Export Citation Format

Share Document