scholarly journals Optimal Control of a Compound Rotorcraft for Engine Performance Enhancement

2020 ◽  
Author(s):  
Calum Scullion ◽  
Stavros Vouros ◽  
Ioannis Goulos ◽  
Devaiah Nalianda ◽  
Vassilios Pachidis
Keyword(s):  
Optimal Control ◽  
Flight Control ◽  
Performance Enhancement ◽  
Engine Performance ◽  
Performance Model ◽  
Flight Speed ◽  
Gaseous Emissions ◽  
Fuel Burn ◽  
Redundant Control ◽  
The Impact

Abstract Demands for rotorcraft with increased flight speed, improved operational performance and reduced environmental impact have led to a drive in research and development of alternative concepts. Compound rotorcraft overcome the flight speed limitations of conventional helicopters with additional lifting and propulsive components. Further to operational benefits, these augmentations provide additional flight control parameters, resulting in control redundancy. This work aims to investigate the impact of optimal control strategies for a generic coaxial compound rotorcraft, equipped with turboshaft engines, targeting the minimization of mission fuel burn and gaseous emissions. The direct redundant controls considered are: (a) main rotor speed, (b) propeller speed, and (c), fuselage pitch attitude. A simulation tool for coaxial compound rotorcraft analysis has been developed and coupled to a zero-dimensional engine performance model and a stirred-reactor combustor model. Firstly, experimental and flight test data were used to provide extensive validation of the developed models. A parametric analysis was then carried out to gain insight into the effect of the redundant controls. This was followed by the derivation of a generalized set of optimal redundant control allocations using a surrogate-assisted genetic algorithm. Application of the optimal redundant control allocations during realistic operational scenarios has demonstrated reductions in fuel burn and NOX of up to 6.93% and 8.74% respectively. The developed method constitutes a rigorous approach to guide the design of control systems for future advanced rotorcraft.

scholarly journals Optimal Control of a Compound Rotorcraft for Engine Performance Enhancement

2020 ◽  
Author(s):  
Calum Scullion ◽  
Stavros Vouros ◽  
Ioannis Goulos ◽  
Devaiah Nalianda ◽  
Vassilios Pachidis
Keyword(s):  
Optimal Control ◽  
Flight Control ◽  
Performance Enhancement ◽  
Engine Performance ◽  
Performance Model ◽  
Flight Speed ◽  
Gaseous Emissions ◽  
Fuel Burn ◽  
Redundant Control ◽  
The Impact

Abstract Demands for rotorcraft with increased flight speed, improved operational performance and reduced environmental impact have led to a drive in research and development of alternative concepts. Compound rotorcraft overcome the flight speed limitations of conventional helicopters with additional lifting and propulsive components. Further to operational benefits, these augmentations provide additional flight control parameters, resulting in control redundancy. This work aims to investigate the impact of optimal control strategies for a generic coaxial compound rotorcraft, equipped with turboshaft engines, targeting the minimization of mission fuel burn and gaseous emissions. The direct redundant controls considered are: (a) main rotor speed, (b) propeller speed, and (c), fuselage pitch attitude. A simulation tool for coaxial compound rotorcraft analysis has been developed and coupled to a zero-dimensional engine performance model and a stirred-reactor combustor model. Firstly, experimental and flight test data were used to provide extensive validation of the developed models. A parametric analysis was then carried out to gain insight into the effect of the redundant controls. This was followed by the derivation of a generalized set of optimal redundant control allocations using a surrogate-assisted genetic algorithm. Application of the optimal redundant control allocations during realistic operational scenarios has demonstrated reductions in fuel burn and NOx of up to 6.93% and 8.74% respectively. The developed method constitutes a rigorous approach to guide the design of control systems for future advanced rotorcraft.

Impact of Engine Degradation on Optimum Aircraft Trajectories: Short Range

2019 ◽  
Author(s):  
R. Navaratne ◽  
V. Sethi ◽  
C. Lawson
Keyword(s):  
Short Range ◽  
Engine Performance ◽  
Performance Model ◽  
Gas Temperature ◽  
Fuel Burn ◽  
The Difference ◽  
Aircraft Trajectory ◽  
Aircraft Trajectories ◽  
The Impact ◽  
Trajectory Optimisation

Abstract This work aims to provide a methodology to enhance the conventional approach of the aircraft trajectory optimisation problem by including engine degradation and real aircraft flight paths within the optimisation framework; thereby the impact of engine degradation on optimum aircraft trajectories were assessed by quantifying the difference in fuel burn and emissions, when flying a trajectory which has been specifically optimised for an aircraft with degraded engines and flying a trajectory which has been optimised for clean engines. For the purpose of this study models of a clean and two degraded engines have been developed based on Exhaust Gas Temperature (EGT) margin deterioration. Aircraft performance model have been developed for short range aircraft with the capability of simulating vertical and horizontal flight profiles provides by the airlines. An emission prediction model was developed to assess NOx emissions of the mission. In addition, a multidisciplinary aircraft trajectory optimisation framework was developed to analyse short range flight trajectories under three cases. Case_1: Aircraft with clean engines, Case_2 and Case_3 were Aircraft with two levels of degraded engines. Two different multi objective optimisation studies were performed; (1) Fuel burn vs Flight time, and (2) Fuel burn vs NOx emission, Finally optimised trajectories generated with degraded engines were compared with the optimised trajectories generated with clean engines. The results have shown impact of engine degradation on optimum aircraft trajectories are significant and in order to reduce fuel burn and emissions aircraft need to fly on an optimised trajectory customised for the degraded engine performance.

Modeling Contra-Rotating Turbomachinery Components for Engine Performance Simulations: The Geared Turbofan With Contra-Rotating Core Case

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
A. Alexiou ◽  
I. Roumeliotis ◽  
N. Aretakis ◽  
A. Tsalavoutas ◽  
K. Mathioudakis
Keyword(s):  
Three Dimensional ◽  
Engine Performance ◽  
Performance Model ◽  
Speed Ratio ◽  
The Core ◽  
Fuel Burn ◽  
Core Concepts ◽  
Additional Table ◽  
Cooling Air Flow ◽  
Cooling Air

This paper presents a method of modeling contra-rotating turbomachinery components for engine performance simulations. The first step is to generate the performance characteristics of such components. In this study, suitably modified one-dimensional mean line codes are used. The characteristics are then converted to three-dimensional tables (maps). Compared to conventional turbomachinery component maps, the speed ratio between the two shafts is included as an additional map parameter and the torque ratio as an additional table. Dedicated component models are then developed that use these maps to simulate design and off-design operation at the component and engine levels. Using this approach, a performance model of a geared turbofan with a contra-rotating core (CRC) is created. This configuration was investigated in the context of the European program “NEW Aero-Engine Core Concepts” (NEWAC). The core consists of a seven-stage compressor and a two-stage turbine without interstage stators and with successive rotors running in the opposite direction through the introduction of a rotating outer spool. Such a configuration results in a reduced parts count, length, weight, and cost of the entire high pressure (HP) system. Additionally, the core efficiency is improved due to reduced cooling air flow requirements. The model is then coupled to an aircraft performance model and a typical mission is carried out. The results are compared against those of a similar configuration employing a conventional core and identical design point performance. For the given aircraft-mission combination and assuming a 10% engine weight saving when using the CRC arrangement over the conventional one, a total fuel burn reduction of 1.1% is predicted.

Modelling Contra-Rotating Turbomachinery Components for Engine Performance Simulations: The Geared Turbofan With Contra-Rotating Core Case

2012 ◽  
Author(s):  
A. Alexiou ◽  
I. Roumeliotis ◽  
N. Aretakis ◽  
A. Tsalavoutas ◽  
K. Mathioudakis
Keyword(s):  
Three Dimensional ◽  
Engine Performance ◽  
Performance Model ◽  
Speed Ratio ◽  
The Core ◽  
Fuel Burn ◽  
Core Concepts ◽  
Additional Table ◽  
Cooling Air Flow ◽  
Cooling Air

This paper presents a method of modelling contra-rotating turbomachinery components for engine performance simulations. The first step is to generate the performance characteristics of such components. In this study, suitably modified one-dimensional mean line codes are used. The characteristics are then converted to three-dimensional tables (maps). Compared to conventional turbomachinery component maps, the speed ratio between the two shafts is included as an additional map parameter and the torque ratio as an additional table. Dedicated component models are then developed that use these maps to simulate design and off-design operation at component and engine level. Using this approach, a performance model of a geared turbofan with a Contra-Rotating Core (CRC) is created. This configuration was investigated in the context of the European program NEWAC (NEW Aero-engine core Concepts). The core consists of a seven-stage compressor and a two-stage turbine without inter-stage stators and with successive rotors running in opposite direction through the introduction of a rotating outer spool. Such a configuration results in reduced parts count, length, weight and cost of the entire HP system. Additionally, the core efficiency is improved due to reduced cooling air flow requirements. The model is then coupled to an aircraft performance model and a typical mission is carried out. The results are compared against those of a similar configuration employing a conventional core and identical design point performance. For the given aircraft-mission combination and assuming a 10% engine weight saving when using the CRC arrangement over the conventional one, a total fuel burn reduction of 1.1% is predicted.

Sensitivity Analysis of an Aircraft Engine Model Under Consideration of Dependent Variables

2021 ◽  
Author(s):  
Julian Salomon ◽  
Jan Göing ◽  
Sebastian Lück ◽  
Matteo Broggi ◽  
Jens Friedrichs ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Engine Performance ◽  
Aircraft Engine ◽  
Interaction Effects ◽  
Performance Model ◽  
Engine Model ◽  
Overall Performance ◽  
Input Variables ◽  
The One ◽  
The Impact

Abstract In this work the impact of combined module variances on the overall performance of a high-bypass aircraft engine is investigated. Therefore, a comprehensive sensitivity analysis on the example of a turbofan engine performance model is provided by means of Kucherenko indices. Direct influences of selected model inputs on key model outputs as well as influences due to interaction effects between these input variables are identified. The selected input variables of the performance model are partly subject to considerable dependencies that are taken into account by the Kucherenko indices. The results confirm known direct influences of deterioration effects on the key performance parameters of the aircraft engine on the one hand, and provide profound insights into complex interaction effects between the components and their impact on the V2500-A1 aircraft engine performance on the other.

Optimizing the Operation of the Intercooled Turbofan Engine

2010 ◽  
Author(s):  
Tomas Gro¨nstedt ◽  
Konstantinos Kyprianidis
Keyword(s):  
Mechanical Design ◽  
Engine Performance ◽  
Turbine Rotor ◽  
Performance Model ◽  
Multidisciplinary Optimization ◽  
Turbofan Engine ◽  
Turbine Rotor Blade ◽  
Low Pressure Turbine ◽  
Fuel Burn ◽  
Exit Temperature

The performance of an intercooled turbofan engine is analysed by multidisciplinary optimization. A model for making preliminary simplified analysis of the mechanical design of the engine is coupled to an aircraft model and an engine performance model. A conventional turbofan engine with technology representative for a year 2020 entry of service engine is compared to a corresponding intercooled engine. A mission fuel burn reduction of 4.3% is observed. The results are analysed in terms of the relevant constraints such as compressor exit temperature, turbine entry temperature, turbine rotor blade temperature and compressor exit blade height. It is then shown that a separate variable exhaust nozzle mounted in conjunction with the intercooler together with a variable low pressure turbine may further improve the fuel burn benefit to 5.5%. Empirical data and a parametric CFD study is used to verify the intercooler heat transfer and pressure loss characteristics.

Impact of Operating and Health Conditions on a Helicopter Turbo-Shaft Hot Section Component Using Creep Factor

2012 ◽  
Vol 225 ◽  
pp. 239-244 ◽  
Author(s):  
Mohammad Fahmi Abdul Ghafir ◽  
Yi Guang Li ◽  
A.A. Wahab ◽  
Siti Nur Mariani Mohd Yunos ◽  
M.F. Yaakub ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Impact Analysis ◽  
Influencing Factor ◽  
Engine Performance ◽  
Performance Model ◽  
Health Conditions ◽  
Estimation Model ◽  
Creep Life ◽  
Life Consumption ◽  
The Impact

The paper investigates the effects of various gas turbine operating and health conditions on its hot section component’s creep life via a simple relative creep life parameter known as Creep Factor. Using the Creep Factor, the correlation between individual gas turbine operating and health parameter and component’s creep life was established and the weight of the impact was measured. Analytical-parametric-based creep life estimation model combined with the Creep Factor approach was developed and integrated with an existing engine performance model to allow the estimation of various hot section component creep lives and the computation of the Creep Factors. The impact analysis was carried out on the high pressure turbine blade of a model turbo-shaft helicopter engine. The results indicate that for a clean engine, the change in engine rotational speed was seen to provide the highest impact on changing the blade’s creep life consumption while for a degraded engine, the presence of compressor fouling has the highest threat in changing the blade’s creep life. The analysis also shows that the Creep Factor is a good indicator of creep life consumption and provides a good technique to rank the influencing factor according to the threat they imposed.

Evaluation of Interstage Water Injection Effect on Compressor and Engine Performance

2004 ◽  
Vol 128 (4) ◽  
pp. 849-856 ◽  
Author(s):  
I. Roumeliotis ◽  
K. Mathioudakis
Keyword(s):  
Performance Enhancement ◽  
Water Injection ◽  
Engine Performance ◽  
Performance Model ◽  
Injection Point ◽  
Effect Of Water ◽  
Compression Model ◽  
Compressor Inlet ◽  
Wet Compression ◽  
Injection Effect

The present paper examines the effect of water injection at the compressor inlet or between stages, on its operation. A wet compression model coupled with an engine performance model is used. The wet compression model produces the compressor performance map when water is present and consists of a one-dimensional stage stacking model, coupled with a droplet evaporation model. The effect of water injection on overall performance and individual stage operation is examined. The map-generation procedure is embedded in an engine performance model and a study of water injection effect on overall engine performance is undertaken. The possibility to evaluate the effect on various parameters such as power, thermal efficiency, surge margin, as well as the progression of droplets through the stages is demonstrated. The results indicate that water injection causes significant stage rematching, leading the compressor toward stall and that the performance enhancement is greater as the injection point moves towards compressor inlet.

Evaluation of Interstage Water Injection Effect on Compressor and Engine Performance

2005 ◽  
Author(s):  
I. Roumeliotis ◽  
K. Mathioudakis
Keyword(s):  
Performance Enhancement ◽  
Water Injection ◽  
Engine Performance ◽  
Performance Model ◽  
Injection Point ◽  
Effect Of Water ◽  
Compression Model ◽  
Compressor Inlet ◽  
Wet Compression ◽  
Injection Effect

The present paper examines the effect of water injection at the compressor inlet or between stages, on its operation. A wet compression model coupled with an engine performance model is used. The wet compression model produces the compressor performance map when water is present and consists of a one dimensional stage stacking model, coupled with a droplet evaporation model. The effect of water injection on overall performance and individual stage operation is examined. The map generation procedure is embedded in an engine performance model and a study of water injection effect on overall engine performance is undertaken. The possibility to evaluate the effect on various parameters such as power, thermal efficiency, surge margin, as well as the progression of droplets through the stages is demonstrated. The results indicate that water injection causes significant stage rematching, leading the compressor towards stall and that the performance enhancement is greater as the injection point moves towards compressor inlet.

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