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Towards a stochastic in-flight thrust determination process
Technical Paper
2007-01-2542
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Traditionally jet engines in-flight thrust determination is a deterministic process that starting from the fan and core measured pressures and temperatures calculates, by many different ways, the intermediate turbomachine parameters up to the exhaust nozzle pressure and temperature while iteratively search for the engine mass flow, attending simultaneously energy, mass and momentum conservation. With this data and the previously determined nozzle coefficients, the engine installed thrust is calculated. These methods are industry standards that are well documented on SAE reports AIR 1703A and AIR 5450. A new approach is proposed in this work, a more stochastic approach, which in fact estimates the engine fan and core pressures and temperatures from initial air mass flow and gross thrust values. Using the Output-Error Method the values of gross thrust and air mass flow are iteratively updated by a modified Newton-Raphson algorithm minimizing the error between the fan and core calculated and measured air pressures and temperatures. The new technique solves in fact, by optimization, the inverse formulation of the in-flight thrust determination problem. The advantages of the new technique over the traditional one is that it has stochastic properties allowing to process the noisy flight test data samples without previous averaging. This paper presents the new technique and demonstrates its application to a set of engine Deck data transformed to sampled data by application of noise.
Authors
Citation
Hoff, J., "Towards a stochastic in-flight thrust determination process," SAE Technical Paper 2007-01-2542, 2007, https://doi.org/10.4271/2007-01-2542.Also In
References
- SAE ARP 775C Gas Turbine Engine Performance Station Identification and Nomenclature SAE USA December 1997
- PART 25 - Airworthiness Standard: Transport Category Airplanes FAA, Department of Transport USA
- AC 25-7A - Flight Test Guide for Certification of Transport Category Airplanes FAA Department of Transport USA
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- SAE AIR 1703A In-Flight Thrust Determination SAE USA Feb. 20 2006
- SAE AIR 5450 Advanced Ducted Propulsor In-Flight Thrust Determination SAE USA
- Morelli, E., A. Klein, V. Determining the accuracy of Maximum Likelihood parameter estimates with colored residuals NASA Report 194893 1994