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.

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.

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.

scholarly journals A Simple and Effective Protein Folding Activity Suitable for Large Lectures

2006 ◽  
Vol 5 (3) ◽  
pp. 264-269 ◽  
Author(s):  
Brian White
Keyword(s):  
Protein Folding ◽  
Noncovalent Interactions ◽  
Three Dimensional ◽  
College Biology ◽  
The Core ◽  
Large Lecture ◽  
Hands On ◽  
Core Concepts ◽  
Large Lecture Classes

This article describes a simple and inexpensive hands-on simulation of protein folding suitable for use in large lecture classes. This activity uses a minimum of parts, tools, and skill to simulate some of the fundamental principles of protein folding. The major concepts targeted are that proteins begin as linear polypeptides and fold to three-dimensional structures, noncovalent interactions drive this folding process, and the final folded shape of a protein depends on its amino acid sequence. At the start of the activity, students are given pieces of insulated wire from which they each construct and fold their own polypeptide. This activity was evaluated in three ways. A random sample of student-generated polypeptides collected after the activity shows that most students were able to create an appropriate structure. After this activity, students (n = 154) completed an open-ended survey. Their responses showed that more than three-quarters of the students learned one or more of the core concepts being demonstrated. Finally, a follow-up survey was conducted seven weeks after the activity; responses to this survey (n = 63) showed that a similar fraction of students still retained these key concepts. This activity should be useful in large introductory-level college biology or biochemistry lectures.

Advanced Exhaust Performance Modelling of Mixed Turbofan Engines: Less is More

2009 ◽  
Author(s):  
J. Wachter ◽  
F. Ko¨pf
Keyword(s):  
Three Dimensional ◽  
Flow Characteristics ◽  
Exhaust System ◽  
Performance Model ◽  
Performance Modelling ◽  
Less Is More ◽  
Turbofan Engines ◽  
Test Execution ◽  
Fuel Burn ◽  
Forced Mixing

Forced mixing devices are commonly used to augment exhaust performance for turbofan engines with low and intermediate bypass ratios as emerging effects like noise and fuel burn reduction associated with the mixing of core and bypass gas streams outbalance the detrimental impacts like additional drag and weight for this engine size. However, the highly three-dimensional flow characteristics cause major challenges for a proper accounting in a simplified one-dimensional thermodynamic performance model of the mixer and nozzle component, which impact the overall engine cycle significantly. It is especially crucial for the determination of fan working lines as well as the generated gross thrust to feed the model with accurate input values. The present paper introduces the usage of stringent flow separated exhaust system models and its impact on rig-test execution and engine analysis. Benefits concerning off-design modeling as well as challenges arising with the outlined methodology are discussed in detail. Furthermore its capability as analysis pretest model is demonstrated by means of sea level testing of a midsized turbofan engine.

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.

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.

Aircraft Engine Performance Improvement by Active Clearance Control in Low Pressure Turbines

2009 ◽  
Author(s):  
Christian Knipser ◽  
Wolfgang Horn ◽  
Stephan Staudacher
Keyword(s):  
Fuel Consumption ◽  
Performance Improvement ◽  
Engine Performance ◽  
Aircraft Engine ◽  
Low Pressure ◽  
Performance Model ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Cooling Air ◽  
Clearance Control

In order to minimize fuel consumption, resulting in reduced operating costs and lower environmental impact, turbofan engines must be of high overall efficiency. The design of the low pressure turbine (LPT) plays a significant role in the development of such engines. During a flight mission changing operating conditions (spool speeds, temperatures, pressures, etc.) cause altering magnitudes of the LPT tip clearance, leading to a decrease in LPT performance. As minimum clearances usually do not occur in steady state cruise condition — the major flight condition concerning fuel consumption — active measures to minimize radial tip clearance (ACC – active clearance control) must be incorporated to achieve a considerable reduction in fuel consumption over the whole flight mission. Actively minimizing radial tip clearance by manipulating the turbine casing requires energy in terms of cooling air (thermal ACC), electrical or hydraulical power (mechanical ACC). The cooling air or the power respectively must be provided by the engine itself, thus partly compensating the benefit gained through the improved LPT behavior. This paper investigates the potential of ACC systems from a whole engine perspective. The approach uses a performance model of a state-of-the-art high bypass turbofan engine with a thermal LPT-ACC system to assess the different benefits and detriments of an enhanced ACC. The overall benefit in TSFC for the simulated engine is compared to measured data of other engines indicating an increase of ACC effectiveness with increasing bypass ratios. To compensate deterioration losses due to single rub-in events, closed-loop controls are required. A tip clearance sensor allows the ACC to adapt to an individual engine. As thermal ACC systems show an optimum benefit with a corresponding optimum ACC cooling air flow, the additional TSFC benefit by compensating deterioration is limited. The achievable overall performance improvement is evaluated for different control loops. Mechanical ACC systems bear the highest potential of eliminating clearance losses, while only minor improvements can be made for thermal ACC systems.

Numerical Simulation of Propulsion System Integration for Very High Bypass Ratio Engines

2012 ◽  
Author(s):  
Thierry Sibilli ◽  
Mark Savill ◽  
Vishal Sethi ◽  
David MacManus ◽  
Andrew M. Rolt
Keyword(s):  
System Integration ◽  
New Technologies ◽  
Engine Performance ◽  
Aircraft Design ◽  
Aircraft Engine ◽  
Fuel Burn ◽  
Active Core ◽  
Core Concepts ◽  
Work Programme ◽  
Bypass Ratio

Due to a trend towards Ultra High Bypass Ratio engines, confirmed in projects like NEWAC (New Aero Engine Core Concepts, an European Sixth Frame Work Programme) the corresponding engine/airframe interference is becoming a key aspect in aircraft design. Therefore detailed aerodynamic investigations are required to evaluate the real benefits of these new technologies. The work presented in this paper is to perform these investigations for two typical twin-engine/low-wing transports, using Computational Fluid Dynamics, in order to create a useful integration module for the in-house aircraft/engine performance software TERA2020 (Techno-economic Environmental and Risk Assessment for 2020). The paper presents results for two NEWAC engines: Intercooled Core Long Range (IC L/R) and the Active Core Short Range (AC S/R). The main results show that the engine horizontal positioning can influence mission fuel burn by up to 6.4% for AC S/R and 3.7% for IC L/R respectively.

Identifying Key Technology Areas to Fundamentally Reduce Risk in Engine Performance and Noise for Future Commercial Applications

2013 ◽  
Author(s):  
Brian K. Kestner ◽  
Hernando Jimenez ◽  
Christopher A. Perullo ◽  
Jeff S. Schutte ◽  
Dimitri N. Mavris
Keyword(s):  
Noise Suppression ◽  
Performance Metrics ◽  
Power Transmission ◽  
Technology Development ◽  
Engine Performance ◽  
Performance Goals ◽  
The Core ◽  
Fuel Burn ◽  
Reduce Risk ◽  
Engine Cycle

There have been many studies in the past which have evaluated the potential fuel savings benefits of various engine technologies applied simultaneously to a gas turbine engine. Coupled with the inclusion of new engine technology is almost always a change to the engine cycle design in order to maximize the full benefits of the technology. Current research focuses on the trends in benefits due to potential technologies and cycle design changes and identifies which specific technology areas can be targeted to reduce risk relative to meeting performance goals. The results are used to identify high priority technologies that increase the chances of meeting performance metrics. Such investigations can add value to government and industry entities that are engaging in aviation technology development programs attempting to simultaneously meet reduction goals for noise and fuel burn. Jet and fan noise are primary sources of noise on current engine architectures. Noise suppression technologies can be applied to current engine designs to suppress sources of noise thereby reducing the noise impact of the engine. Similarly, the engine cycle can be changed to reduce noise and fuel burn. The critical link is that feasible engine cycles are tightly coupled to the subsystem technologies applied to various engine components. This leads to two critical questions. First, what part of the engine cycle is key to simultaneously meeting noise and fuel burn goals? This inevitably leads to one of three areas, the propulsor (BPR), the core (OPR), or the transmission mechanism between the core and propulsor. The other question is: which subsystem technologies are crucial to achieve the necessary core, propulsor, or power transmission improvements? To answer these questions, this study examines and quantifies the potential benefits in technologies developed for both noise source reduction and thermal / propulsive efficiency increases. Trade studies on the potential impacts of each of the technologies are performed to capture the sensitivity on fuel burn and noise from changes to assumed benefits of the engine cycle and applied subsystem technologies. It will be demonstrated that a geared transmission is the primary enabler to simultaneously meeting performance goals. Should the geared transmission fall short, other areas of improvement simply cannot overcome the shortfall in fuel burn and noise.

scholarly journals Thermal Characteristics Study of the Bump Foil Thrust Gas Bearing

2021 ◽  
Vol 11 (9) ◽  
pp. 4311
Author(s):  
Xiaomin Liu ◽  
Changlin Li ◽  
Jianjun Du ◽  
Guodong Nan
Keyword(s):  
Gas Flow ◽  
Three Dimensional ◽  
Thermal Characteristics ◽  
Rotor Speed ◽  
External Cooling ◽  
Deformation Equation ◽  
Simulation And Experiment ◽  
Cooling Air Flow ◽  
Cooling Air ◽  
Gas Bearing

In this paper, a thermo-hydrodynamic model of the bump foil thrust gas bearing is developed, which solves the coupled gas film three-dimensional energy equation, non-isothermal Reynolds equation, and the foil deformation equation. The effects of bearing speed, thrust load, and external cooling gas on the bearing temperature field are calculated and analyzed. The test rig of foil thrust gas bearing was built to measure the bearing temperature under different working conditions. Both simulation and experiment results show that there exist temperature gradients on the top foil both in the circumferential and radial directions. The simulation results also shows that the top foil side of the gas film has the highest temperature value in the entire lubrication field, and the position of highest temperature moves radially inward on the thrust plate side as the rotor speed increases. The gas film temperature increases with the increasing rotor speed and bearing static load, and rotor speed has greater effects on the temperature variation. Cooling air flow passing through the bump foil is also considered in the simulations, and the cooling efficiency decreases as the mass of gas flow increases.

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