System Identification of Jet Engines

1999 ◽  
Vol 122 (1) ◽  
pp. 19-26 ◽  
Author(s):  
N. Sugiyama
Keyword(s):  
System Identification ◽  
Jet Engines ◽  
Turbofan Engine ◽  
Jet Engine ◽  
Performance Change ◽  
Electric Control ◽  
Advanced Control ◽  
Identification Technique ◽  
Using Data ◽  
Engine Components

System identification plays an important role in advanced control systems for jet engines, in which controls are performed adaptively using data from the actual engine and the identified engine. An identification technique for jet engine using the Constant Gain Extended Kalman Filter (CGEKF) is described. The filter is constructed for a two-spool turbofan engine. The CGEKF filter developed here can recognize parameter change in engine components and estimate unmeasurable variables over whole flight conditions. These capabilities are useful for an advanced Full Authority Digital Electric Control (FADEC). Effects of measurement noise and bias, effects of operating point and unpredicted performance change are discussed. Some experimental results using the actual engine are shown to evaluate the effectiveness of CGEKF filter. [S0742-4795(00)00401-4]

scholarly journals System Identification of Jet Engines

1998 ◽  
Author(s):  
Nanahisa Sugiyama
Keyword(s):  
System Identification ◽  
Jet Engines ◽  
Turbofan Engine ◽  
Jet Engine ◽  
Performance Change ◽  
Electric Control ◽  
Advanced Control ◽  
Identification Technique ◽  
Using Data ◽  
Engine Components

System identification plays an important role in advanced control systems for jet engines, in which controls are performed adaptively using data from the actual engine and the identified engine. An identification technique for jet engine using the Constant Gain Extended Kalman Filter (CGEKF) is described. The filter is constructed for a two-spool turbofan engine. The CGEKF filter developed here can recognize parameter change in engine components and estimate unmeasurable variables over whole flight conditions. These capabilities are useful for an advanced Full Authority Digital Electric Control (FADEC). Effects of measurement noise and bias, effects of operating point and unpredicted performance change are discussed. Some experimental results using the actual engine are shown to evaluate the effectiveness of CGEKF filter.

Multiparameter Real-World System Identification using Iterative Residual Tuning

2021 ◽  
pp. 1-12
Author(s):  
Adam Allevato ◽  
Mitch W Pryor ◽  
Andrea L. Thomaz
Keyword(s):  
System Identification ◽  
Robot Control ◽  
Tracking Error ◽  
Nonlinear System Identification ◽  
Visual Observation ◽  
Free System ◽  
Proposed Model ◽  
Derivative Free ◽  
Identification Technique ◽  
Using Data

Abstract In this work we consider the problem of nonlinear system identification, using data to learn multiple and often coupled parameters that allow a simulator to more accurately model a physical system or mechanism and close the so-called reality gap for more accurate robot control. Our approach uses iterative residual tuning (IRT), a recently-developed derivative-free system identification technique that utilizes neural networks and visual observation to estimate parameter differences between a proposed model and a target model. We develop several modifications to the basic IRT approach and apply it to the system identification of a 5-parameter model of a marble rolling in a robot-controlled labyrinth game mechanism. We validate our technique both in simulation—where we outperform two baselines—and on a real system, where we achieve marble tracking error of 4% after just 5 optimization iterations.

Multiparameter Real-World System Identification Using Iterative Residual Tuning

2020 ◽  
Author(s):  
Adam Allevato ◽  
Mitch Pryor ◽  
Andrea L. Thomaz
Keyword(s):  
System Identification ◽  
Robot Control ◽  
Tracking Error ◽  
Nonlinear System Identification ◽  
Visual Observation ◽  
Free System ◽  
Proposed Model ◽  
Derivative Free ◽  
Identification Technique ◽  
Using Data

Abstract In this work we consider the problem of nonlinear system identification, using data to learn multiple and often coupled parameters that allow a simulator to more accurately model a physical system and close the so-called reality gap for more accurate robot control. Our approach uses iterative residual tuning (IRT), a recently-developed derivative-free system identification technique that utilizes neural networks and visual observation to estimate parameter differences between a proposed model and a target model. We develop several modifications to the basic IRT approach and apply it to the system identification of a 5-parameter model of a marble rolling in a robot-controlled labyrinth game mechanism. We validate our technique both in simulation — where we outperform two baselines — and on a real system, where we achieve marble tracking error of 4.02% after just 5 optimization iterations.

FLYLITE ZRE-1

Alloy Digest ◽  
1952 ◽  
Vol 1 (2) ◽  
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Base Alloy ◽  
Heat Treating ◽  
Jet Engine ◽  
Temperature Performance ◽  
Engine Components ◽  
Temperature Applications

Abstract Flylite ZRE-1 is a creep resistant magnesium-base alloy primarily designed for jet engine components and other high temperature applications. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive strength as well as creep. It also includes information on high temperature performance as well as casting, heat treating, machining, and joining. Filing Code: Mg-2. Producer or source: Howard Foundry Company.

A System Identification Method for Excitation-Frequency Dependent Rotordynamic Coefficients

2012 ◽  
Author(s):  
Timothy W. Dimond ◽  
Amir A. Younan ◽  
Paul Allaire
Keyword(s):  
System Identification ◽  
Measurement Uncertainty ◽  
Excitation Frequency ◽  
Frequency Dependent ◽  
Rotordynamic Coefficients ◽  
Adjoint Systems ◽  
Dynamic Coefficients ◽  
Backward Whirl ◽  
Identification Technique ◽  
Damped Systems

Experimental identification of rotordynamic systems presents unique challenges. Gyroscopics, generally damped systems, and non-self-adjoint systems due to fluid structure interaction forces mean that symmetry cannot be used to reduce the number of parameters to be identified. Rotordynamic system experimental measurements are often noisy, which complicates comparisons with theory. When linearized, the resulting dynamic coefficients are also often a function of excitation frequency, as distinct from operating speed. In this paper, a frequency domain system identification technique is presented that addresses these issues for rigid-rotor test rigs. The method employs power spectral density functions and forward and backward whirl orbits to obtain the excitation frequency dependent effective stiffness and damping. The method is highly suited for use with experiments that employ active magnetic exciters that can perturb the rotor in the forward and backward whirl directions. Simulation examples are provided for excitation-frequency reduced tilting pad bearing dynamic coefficients. In the simulations, 20 and 50 percent Gaussian output noise was considered. Based on ensemble averages of the coefficient estimates, the 95 percent confidence intervals due to noise effects were within 1.2% of the identified value. The method is suitable for identification of linear dynamic coefficients for rotordynamic system components referenced to shaft motion. The method can be used to reduce the effect of noise on measurement uncertainty. The statistical framework can also be used to make decisions about experimental run times and acceptable levels of measurement uncertainty. The data obtained from such an experimental design can be used to verify component models and give rotordynamicists greater confidence in the design of turbomachinery.

Practical Bypass Mixing Systems for Fan Jet Aero Engines

1966 ◽  
Vol 17 (2) ◽  
pp. 141-160 ◽  
Author(s):  
T. H. Frost
Keyword(s):  
Gas Turbines ◽  
Minimum Weight ◽  
Jet Engines ◽  
Metal Interface ◽  
Combustion Chambers ◽  
Propulsion Systems ◽  
Jet Engine ◽  
Aero Engines ◽  
Corrugated Metal ◽  
Constant Static Pressure

SummaryMixing systems have many applications in gas turbines and aircraft jet propulsion, e.g. mixing zones in combustion chambers, ejectors for jet lift thrust augmentors and supersonic propulsion systems. A further application similar to that of combustion chamber mixing is that of mixing the cold and hot exhausts of a bypass jet engine. These are both characterised by mixing at constant static pressure and approximately constant total pressure as opposed to the more general case of unequal pressures in ejector systems (Fig. 1).The exhaust mixing process as used in Rolls-Royce bypass jet engines, e.g. Spey and Conway, enables the potential of the bypass principle, in terms of minimum weight and fuel consumption, to be exploited by a simple practical device.This is achieved by mixing the two streams in a common duct of fairly short dimensions with a corrugated metal interface on the inlet side. The consideration of these practical systems forms the main topic of this paper.

Design and Analysis of an Intentional Mistuning Experiment Reducing Flutter Susceptibility and Minimizing Forced Response of a Jet Engine Fan

2017 ◽  
Author(s):  
Felix Figaschewsky ◽  
Arnold Kühhorn ◽  
Bernd Beirow ◽  
Jens Nipkau ◽  
Thomas Giersch ◽  
...  
Keyword(s):  
Computational Model ◽  
Paint Layer ◽  
Forced Vibrations ◽  
Forced Response ◽  
Operating Conditions ◽  
Jet Engines ◽  
Jet Engine ◽  
Aspect Ratios ◽  
Engine Order ◽  
Stall Flutter

Recent demands for a reduction of specific fuel consumption of jet engines have been opposed by increasing propulsive efficiency with higher bypass ratios and increased engine sizes. At the same time the challenge for the engine development is to design safe and efficient fan blades of high aspect ratios. Since the fan is the very first rotor stage, it experiences significant distortions in the incoming flow depending on the operating conditions. Flow distortions do not only lead to a performance and stall margin loss but also to remarkable low engine order (LEO) excitation responsible for forced vibrations of fundamental modes. Additionally, fans of jet engines typically suffer from stall flutter, which can be additionally amplified by reflections of acoustic pressure waves at the intake. Stall flutter appears before approaching the stall line on the fan’s characteristic and limits its stable operating range. Despite the fact that this “flutter bite” usually affects only a very narrow speed range, it reduces the overall margin of safe operation significantly. With increasing aspect ratios of ultra-high bypass ratio jet engines the flutter susceptibility will probably increase further and emphasizes the importance of considering aeromechanical analyses early in the design phase of future fans. This paper aims at proving that intentional mistuning is able to remove the flutter bite of modern jet engine fans without raising issues due to heavily increased forced vibrations induced by LEO excitation. Whereas intentional mistuning is an established technology in mitigating flutter, it is also known to amplify the forced response. However, recent investigations considering aeroelastic coupling revealed that under specific circumstances mistuning can also reduce the forced response due to engine order excitation. In order to allow a direct comparison and to limit costs as well as effort at the same time, the intentional mistuning is introduced in a non-destructive way by applying heavy paint to the blades. Its impact on the blade’s natural frequencies is estimated via finite element models with an additional paint layer. In parallel, this procedure is experimentally verified with painted fan blades in the laboratory. A validated SNM (subset of nominal system modes) representation of the fan is used as a computational model to characterize its mistuned vibration behavior. Its validation is done by comparing mistuned mode shape envelopes and frequencies of an experimental modal analysis at rest with those obtained by the updated computational model. In order to find a mistuning pattern minimizing the forced response of mode 1 and 2 at the same time and satisfying stability and imbalance constraints, a multi-objective optimization has been carried out. Finally, the beneficial properties of the optimized mistuning pattern are verified in a rig test of the painted rotor.

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