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Bypass Ratio

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Pericles Pilidis – 1st expert on this subject based on the ideXlab platform

  • Thrust Reverser for a Separate Exhaust High Bypass Ratio Turbofan Engine and its Effect on Aircraft and Engine Performance
    Volume 1: Aircraft Engine; Ceramics; Coal Biomass and Alternative Fuels; Wind Turbine Technology, 2011
    Co-Authors: Tashfeen Mahmood, Anthony Jackson, Vishal Sethi, Pericles Pilidis

    Abstract:

    This paper discusses thrust reversing techniques for a separate exhaust high Bypass Ratio turbofan engine and its effect on aircraft and engine performance. Cranfield University is developing suitable thrust reverser performance models. These thrust reverser performance models will subsequently be integrated within the TERA (Techno-economic Environmental Risk Analysis) architecture thereby allowing for more detailed and accurate representations of aircraft and engine performance during the landing phase of a typical civil aircraft mission. The turbofan engine chosen for this study was CUTS_TF (Cranfield University Twin Spool Turbofan) which is similar to the CFM56-5B4 engine and the information available in the public domain is used for the engine performance analysis along with the Gas Turbine Performance Software, ‘GasTurb 10’ [1]. The CUTEA (Cranfield University Twin Engine Aircraft) which is similar to the Airbus A320 is used alongside with the engine model for the thrust reverser performance calculations. The aim of this research paper is to investigate the effects on aircraft and engine performance characteristics due to the pivoting door type thrust reverser deployment. The paper will look into the overall engine performance characteristics and how the engine components get affected when the thrust reversers come into opeRation. This includes the changes into the operating point of fan, booster, HP compressor, HP turbine, LP turbine, Bypass nozzle and core nozzle. Also, thrust reverser performance analyses were performed (at aircraft/engine system level) by varying the reverser exit area by ± 5% and its effect on aircraft deceleRation rate, deceleRation time and landing distances were observed.

  • thrust reverser for a mixed exhaust high Bypass Ratio turbofan engine and its effect on aircraft and engine performance
    Volume 1: Aircraft Engine; Ceramics; Coal Biomass and Alternative Fuels; Controls Diagnostics and Instrumentation, 2011
    Co-Authors: Tashfeen Mahmood, Pericles Pilidis, Anthony Jackson, Syed Muhammad Hassan Rizvi, Mark Savill, Vishal Sethi

    Abstract:

    This paper discusses thrust reversing techniques for a separate exhaust high Bypass Ratio turbofan engine and its effect on aircraft and engine performance. Cranfield University is developing suitable thrust reverser performance models. These thrust reverser performance models will subsequently be integrated within the TERA (Techno-economic Environmental Risk Analysis) architecture thereby allowing for more detailed and accurate representations of aircraft and engine performance during the landing phase of a typical civil aircraft mission. The turbofan engine chosen for this study was CUTS_TF (Cranfield University Twin Spool Turbofan) which is similar to the CFM56-5B4 engine and the information available in the public domain is used for the engine performance analysis along with the Gas Turbine Performance Software, ‘GasTurb 10’ [1]. The CUTEA (Cranfield University Twin Engine Aircraft) which is similar to the Airbus A320 is used alongside with the engine model for the thrust reverser performance calculations. The aim of this research paper is to investigate the effects on aircraft and engine performance characteristics due to the pivoting door type thrust reverser deployment. The paper will look into the overall engine performance characteristics and how the engine components get affected when the thrust reversers come into opeRation. This includes the changes into the operating point of fan, booster, HP compressor, HP turbine, LP turbine, Bypass nozzle and core nozzle. Also, thrust reverser performance analyses were performed (at aircraft/engine system level) by varying the reverser exit area by ± 5% and its effect on aircraft deceleRation rate, deceleRation time and landing distances were observed.Copyright © 2011 by ASME

  • investigating the emissions and performance of high Bypass Ratio aero engines
    Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering, 2008
    Co-Authors: S Sorato, Daniele Pascovici, S O T Ogaji, Pericles Pilidis

    Abstract:

    AbstractIn the last decades the development of new technologies and methods of analysis has brought a continuous improvement of the performance of aeronautical jet engines among which are reductions of polluting substances and noise. In this vein, and in accordance with the general attention given environmental issues by the scientific community and governments, a first analysis has been conducted to assess the potential of new types of engines to meet the green environmental expectations. The objects of the study are two powerplants, one with Bypass Ratio (BPR) 5, used as baseline, and the other with BPR 12. A parametric analysis of the performance and the emissions of these engines was performed using software which directly coupled models of engine performance, emissions, and aircraft opeRations. Design-point (take-off) and off-design (whole of flight-mission) cases have been considered in order to show the different scenarios and information they could present. Lefebvre equations were used and calibra…

Victor Mileshin – 2nd expert on this subject based on the ideXlab platform

  • Computational Investigation Of Aerodynamic And Acoustic Characteristics Of Counter Rotating Fan With Ultra High Bypass Ratio
    12th European Conference on Turbomachinery Fluid Dynamics and hermodynamics, 2020
    Co-Authors: Iaroslav Druzhinin, Anton Rossikhin, Victor Mileshin

    Abstract:

    A computational investigation of aerodynamic characteristics of model counter-rotating fan with BPR=20, developed in CIAM in the framework of European Project COBRA (Innovative Counter rotating fan system for high Bypass Ratio Aircraft engine), is presented in the work. Unsteady nature of the flow in counter-rotating fan has been studied including analysis of rotor-rotor interaction intensity and unsteady viscous wakes propagation through the axial gap and second rotor blade passages. The results of numerical investigation of the fan tone noise in approach opeRational conditions are also presented. The acoustic calculations were performed using in-house CIAM aeroacoustic code 3DAS. Directivity diagrams for the first 16 harmonics of tone noise in the forward hemisphere, obtained in the calculation, are shown. Comparison between these results and analogous results for model HBR counter-rotating fan with BPR=10 (designed in VITAL project) is performed. Additionally results were compared with experimental results for HBR fan.

  • Numerical and Experimental Investigation of Acoustic Characteristics of Model Ultra High Bypass Ratio Counter Rotating Fan
    Volume 2B: Turbomachinery, 2018
    Co-Authors: Anton Rossikhin, Iaroslav Druzhinin, Iurii Khaletskii, Victor Mileshin

    Abstract:

    A computational investigation of acoustic characteristics of model ducted counter-rotating fan COBRA-1 with ultra-high Bypass Ratio BPR = 20, developed in CIAM in the framework of European Project COBRA (Innovative Counter rOtating fan system for high Bypass Ratio Aircraft engine), is presented in the paper. Calculations of acoustic characteristics of the fan were performed at five opeRational conditions. For three of them the sums of rotation frequencies of rotors corresponded to those expected for approach conditions, and they differed from each other by relations between frequencies of rotors, and for other two the sums of rotation frequencies corresponded to cutback and sideline opeRational conditions. Numerical investigations were conducted using the method of 3D numerical calculation of interaction between fan rows implemented in 3DAS (3 Dimensional Acoustics Solver) CIAM in-house solver. The data were compared with the results of the experiments conducted in the CIAM test rig C-3A. The results of comparison show satisfactory qualitative and, in some positions of microphones, quantitative agreement between the results of the simulation and the experiment. Both results demonstrate strong influence of relation between rotation frequencies of rotors on acoustic characteristics and significant dominance of noise radiated from the nozzle over the noise radiated from the inlet.

  • Numerical and Experimental Investigation of Aerodynamic Characteristics of Model Ultra High Bypass Ratio Counter Rotating Fan
    Volume 2A: Turbomachinery, 2018
    Co-Authors: Iaroslav Druzhinin, Victor Mileshin, Vladimir Korzhnev

    Abstract:

    One of the perspective schemes of air breathing engine is a scheme with Ultra High Bypass Ratio (BPR 16…25) Counter Rotating Fan. This solution potentially allows significant increase of fuel efficiency compared to modern conventional turbofans.
    The model UHBR counter rotating fan named COBRA-1 was developed by CIAM within the framework of European Project COBRA (Innovative Counter rOtating fan system for high Bypass Ratio Aircraft engine). The fan was designed using up-to-date 1D, 2D and 3D methods. COBRA-1 is a 0.7 m diameter model of counter rotating fan driven by a planetary reduction gearbox. The Bypass Ratio of COBRA-1 is 20. The R2/R1 torque Ratio was chosen to obtain 1.42-muliple prevalence in power for 2nd row. The blade numbers are 8/12 for R1/R2 correspondingly. Final geometry of airfoils was defined by 3D profiling process to achieve required aerodynamics and acoustic parameters. Application of control-diffusion airfoils allows reaching high integral performances: specific mass flow equals 211 kg/(s*m^2) and isentropic efficiency at design point is higher than 0.93.
    The paper presents results of computational simulation of the flow in UHBR fan COBRA-1 based on 3D steady RANS method, 3D URANS and Non-Linear Harmonic method for different opeRation conditions in comparison with experimental data. Numerical simulation was carried out using Numeca FINE TURBO software package. Steady RANS approach was used during design process to make quick estimation of performances at different rpm. 3D URANS simulation was conducted to analyze unsteady wake-blade and shock-wave interaction and to make a decision about sufficient value of axial gap between rotors.
    The COBRA-1 fan was tested in CIAM at C3-A test facility which allows conducting a wide range of measurements of local and integral parameters including acoustics of ducted counter rotating fan at different operating conditions.
    Experimental results demonstrate a high level of integral performances and good agreement with computed values.
    Significant part of numerical and experimental investigation is devoted to effect of gear-box requirements on aerodynamics. C3-A rig allows to set rotational speed of rotors independently and measure torques at each shaft to achieve required torque Ratio and study the influence of small (3–5%) deviation in rpm on aerodynamic characteristics.

P G Tucker – 3rd expert on this subject based on the ideXlab platform

  • les rans of installed ultra high Bypass Ratio coaxial jet aeroacoustics with flight stream
    AIAA Journal, 2019
    Co-Authors: James Tyacke, Zhongnan Wang, P G Tucker

    Abstract:

    Using large-eddy simulation–Reynolds-averaged Navier–Stokes (LES–RANS), this paper studies a round coaxial nozzle with an ultra-high Bypass Ratio of 15, with and without a wing-flap geometry. Depen…

  • large eddy simulation of serRation effects on an ultra high Bypass Ratio engine exhaust jet
    Comptes Rendus Mecanique, 2018
    Co-Authors: Zhongnan Wang, James Tyacke, P G Tucker

    Abstract:

    Abstract Serrated jet nozzles are considered to be an efficient and practical passive control approach for jet noise. However, some fundamental mechanisms of serRation effects on jet noise are not fully understood, especially in terms of the sound source. In this paper, a high-fidelity simulation framework using large-eddy simulation (LES) is demonstrated to predict near-field turbulence and far-field acoustics from an ultra-high-BypassRatio engine with round and serrated nozzles. Far-field sound is predicted using Ffowcs Willams–Hawkings (FWH) integRation. The results show that the serrated nozzle increases mixing near the nozzle and hence the turbulence decay rate, reducing the turbulence level downstream. The serRations shift the energy from the low frequencies to the high frequencies and decrease overall sound pressure levels by about 3 dB over the low-frequency range. Sound sources are analysed based on fourth-order space–time correlations. There are six major source components ( R 1111 , R 2222 , R 3333 , R 1313 , R 1212 , and R 2323 ) inside the jet shear layers. The serRations are able to reduce the amplitude of these source terms, causing them to decay rapidly to a level below the round nozzle jet within 2D downstream of the nozzle.

  • les rans of installed ultra high Bypass Ratio coaxial jet aeroacoustics with a finite span wing flap geometry and flight stream part 1 round nozzle
    AIAA CEAS Aeroacoustics Conference, 2017
    Co-Authors: James Tyacke, Zhongnan Wang, P G Tucker

    Abstract:

    © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. The jet noise produced by aeroengines is a critical topic in engine design. Large-Eddy Simulation (LES) and hybrid LES-Reynolds-Averaged Navier-Stokes (LES-RANS), provides a method to increase understanding of influences on the noise produced. Installed jet noise modelling has received less attention than isolated jet noise yet is becoming more important for design. Here, using LES-RANS, a coaxial nozzle with an ultra-high BypassRatio of 15 is studied with and without a wing-flap geometry. The Bypass Ratio leads the nozzle to become extremely close to the wing-flap geometry introducing strong installation effects. Two different flap deflections of 8 and 14 degrees are contrasted with an isolated round nozzle. A flight stream is applied and an FWH surface placement procedure for installed jets is proposed. The installed cases generate more directional noise at mid-low frequencies as the presence of the flap trailing edge produces a strong dipole source. Second order space-time correlations reveal length and time scales in the flow. Fourth order space-time correlations indicate increasing magnitudes of the dominant noise source components with in increasing flap angle and may lead to improved acoustics models.