Adaptive and Passive Flow Control for Fan Broadband Noise Reduction Selected final results Lars Enghardt, DLR Berlin FLOCON project coordinator September 2008 August 2012
Introduction Motivation Air traffic is predicted to grow by 5% per year in the short and medium term. Technology advances are required to achieve his growth with acceptable levels of noise in particular at airport surroundings. Fan broadband noise is one of the most important aircraft noise sources at aircraft start and landing conditions. Objectives Design noise reduction concepts and associated devices able to reduce fan broadband noise at source. Assess the noise reduction concepts by conducting lab-scale experiments (to TRL 4). Complement the experiments by numerical simulations that are assessing the capability of currently available numerical tools to design low broadband noise treatments and configurations. Develop understanding of the mechanisms involved and extrapolate the results to the aero-engine environment using state-of-the-art numerical methods. Select the best concepts by balancing noise benefit and integration impact. 15.11.2015 2
Research centers: DLR - Deutsches Zentrum für Luft und Raumfahrt (DE) ONERA - Office National d Études et Recherches Aérospatiales (FR) ISVR - Institute of Sound and Vibration Research (UK) NLR - Nationaal Lucht- en Ruimtevaart Laboratorium (NL) Industrial partners: Snecma Moteurs (FR) Rolls-Royce plc (UK) EADS Innovation Works (DE) MTU Aero Engines (DE) VOLVO Aero Corporation (SW) AVIO SpA (IT) Universities: Ecole Centrale de Lyon (FR) Universität Siegen (DE) Chalmers University of Technology (SW) Technische Universität Berlin (DE) SME: Fluorem SAS (FR) Microflown Technologies BV (NL) Sandu M. Constantin PF (RO) EU FP7, 1 st Call, Level 1 Project Consortium Budget: 5.3 M (EU funding 3.5 M ) Project start: 1. September 2008 Duration: 4 years (12 months extension at no costs) Coordination: DLR Berlin 15.11.2015 3
Work Package 2: Airfoil treatments for low-noise Objective Development of leading edge and trailing edge treatments for reducing airfoil self-noise and interaction noise and for reducing the turbulence in the wake. Workplan Demonstration and validation of these treatments in an open jet wind tunnel facility (TRL 2) Down-selection of the best trailing edge treatments for testing in a cascade rig (TRL 3) and of the best leading edge treatments for testing in a fan rig in WP3(TRL 4). Modelling of these treatments using RANS and LES CFD simulations. 15.11.2015 4
ISVR open jet wind tunnel Airfoil to be investigated 15.11.2015 5
Leading edge treatment 20 40 U [m/s] 60 0 5 10 15 4 3.5 3 2.5 2 1.5 1 0.5 0-0.5-1 Geometrical AoA [degree] Down select of best LE treatment: ONERA wavy pattern OASWL reduction [dba] TE LE1 Treatments LE2 LE3 0 ONERA LE 5 10 15 20.0% 0.0% -20.0% -40.0% -60.0% -80.0% -100.0% AoA [degree] Geometrical angle of attack [degree] C L reduction CL reduction 15.11.2015 6
ONERA Euler computations on wavy-edge case Calculation : V. Clair 3D multi-bloc grid with 1 motif of 2S wing Acoustic pressure field (Pa) 15.11.2015 7
Trailing edge treatment 20 40 60 U [m/s] 0 5 10 15 2 1.5 1 0.5 0 3 2.5-0.5-1 4 3.5 OASWL reduction [dba] Geometrical AoA [degree] TE TE15 Treatments Down select of best TE treatment: ISVR serrated edge TE17 0 ISVR TE 10.0% C L reduction 8.0% 6.0% 4.0% CL reduction 2.0% 0.0% -2.0% 15 10 5 Geometrical angle of attack [degree] AoA [degree] 15.11.2015 8
AVIO 3D LES on Treated airfoils ROOT MID TIP ROOT MID TIP Velocity on a plane normal to the serration plate 15.11.2015 Slide 9 9
ISVR tandem experiment 15.11.2015 10
Work Package 3: Casing and airfoil treatments for low noise in a fan stage Objective Development of new and innovative technologies for fan broadband noise reduction focusing on airfoil treatments and the interaction between blade tip and fan casing. Workplan Demonstration and validation of these technologies (selected best concept from WP2, special overtip treatment) on a low speed laboratory rotating rig Demonstration of vane trailing edge treatment technology for fan broadband noise reduction under rotating rig flow conditions 15.11.2015 11
EADS low speed fan rig 15.11.2015 12
EADS - Overtip acoustic treatment Tuneable Overtip Acoustic Treatment 15.11.2015 13
OGV treatments OGV Treatment CFD / CAA Porous Trailing Edge Sinter metal spheres 15.11.2015 14
SN / FLU: Cavity Treatment 15.11.2015 15
Work Package 4: Flow Control in a Fan Stage Objective To develop and assess several broadband noise reduction concepts by means of flow control in a fan-ogv stage. To understand the physical influence of the flow control concepts on broadband noise. Workplan Support the assessment of each concept with numerical and experimental investigations. Achieve broadband noise reductions in experiments performed under representative conditions of a fan-stage. 15.11.2015 16
DLR laboratory scale fan rig microphone array mass flow meter duct section for suction continous circumferential slit at rotor LE radial blower DAQ system 15.11.2015 17
NLR: Source localization and azimuthal mode decomposition X-Noise EV FC Meeting, Lausanne 15.11.2015 18
Adaptation of stator vane loading TUB: Noise impact of Gurney flaps DLR: Stator with variable vane stagger angle TUB: Instantaneous spanwise vorticity and pressure time derivative X-Noise EV FC Meeting, Lausanne 15.11.2015 19
Trailing edge blowing MTU: Simulation of wake filling (different slit counts) USI: Rotor blade with internal channels X-Noise EV FC Meeting, Lausanne 15.11.2015 20
Wake filling Experimental assessment of the wake filling Supply of pressurized air 5 slots in the rotor trailing edge 15.11.2015 21
Wake filling Turbulence intensity: no wake filling with wake filling (blowing 142 g/s) Axial Velocity: 15.11.2015 22
ONERA: LES computation results comparison of baseline and blowing case Average relative velocity amplitude and streamlines near the trailing edge of the rotor 15.11.2015 23
Wake filling (post FLOCON) 15.11.2015 24
Wake filling (post FLOCON) 15.11.2015 25
Technology Evaluation Virtual platforms used for the in-flight noise transposition: The FLOCON technology is assessed on the Short-Medium Range (SMR) and Long-Range (LR) OPENAIR virtual aircraft platforms The SMR engine platform AP2-EP1b - is a turbofan BPR 9 engine - engine modelling provided by SN - The technology level of this engine is coherent with an initial EIS date in year 2012 15.11.2015 26
Technology Evaluation FLOCON technologies impacts EPNL total (engine + airframe) WP2 0 Delta EPNL total (engine+airframe) -0.05-0.1-0.15-0.2-0.25-0.3 Wavy LE Microfiber LE Porous LE Porous TE Saw-tooth serrations Butterfly TE -0.35 15.11.2015 27
Technology Evaluation 15.11.2015 28
Technology Evaluation FLOCON technologies impacts EPNL total (engine + airframe) WP4 0.15 Delta EPNL total (engine+airframe) 0.1 0.05 0-0.05-0.1-0.15-0.2-0.25 Gurney flaps T4.1 Suction of rotor vortex T4.2 Wake-filling T4.3 15.11.2015 29
Summary: Final results A wide range of concepts was considered and developed to Technology Readiness Level 4 (laboratory scale validation): Rotor trailing edge blowing Rotor tip vortex suction Rotor overtip treatments Rotor and Stator leading and trailing edge treatments Partly lined stator vanes Experiments were performed on 4 rigs: two rotating rigs, supported by more detailed measurements on a single airfoil and on a cascade. Numerical methods were used to optimize the concepts for experimental validation and to extrapolate the results from laboratory scale to real engine application. The potential benefit of each concept was assessed, including any associated penalties (weight, complexity, aerodynamic performance). Recommendations were made as to which concepts could be integrated into new engine designs or will require further validation at industrial rig or full engine-scale. 15.11.2015 30