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Click to edit Master title style For STAR South East Asian Conference 2015 Click to edit Master text styles Second level Prediction of noise emission from the NASA SR-2 Propeller Third level Fourth level Fifth level 8-9 June 2015 Mr Voo Keng Soon Mr Tan Chun Hern Mr Lim Nee Sheng Winson Dr Siauw Wei Long 1 Slide 1

Click to edit Master title style Click to edit Master text styles A big thank you to CD-adapco Second level Third level for the provision of technical assistance and advice! Fourth level Fifth level Dr Mark Farrall Dr Fred Mendonça Dr Amel Boudjir Dr Jason Fernandes 2 Slide 2

Motivation Click to edit Master title style • Fundamental study of noise emission from flow over propeller Click to edit Master text styles • Comparison of the usage of acoustics analogy and direct Second level measurement method for computational aeroacoustics Third level • Investigate the appropriate usage of Moving Reference Frame Fourth level Fifth level and Rigid Body Motion (sliding mesh) methodologies in the modelling of the propeller • Study the behaviour of the propeller tip vortices in the presence of a generic wing • NASA SR-2 propeller selected as validation case due to the availability of open source data 3 Slide 3

Overview Click to edit Master title style • Propeller Basics Click to edit Master text styles • Simulation Methodology Second level • Generation of SR-2 propeller CAD Third level Fourth level • Differences between CFD Setups Fifth level • CFD Setup of SR-2 propeller • SR-2: Analysis • Propeller in the Presence of Generic Wing • SR-2 + NACA0010: Analysis • Summary 4 Slide 4

Propeller Basics Click to edit Master title style • [1] held measured noise level and corresponding spectral representations on a Cessna 172N (two- Click to edit Master text styles blade propeller) while [2] tested the Cessna FR172F Second level (three-blade propeller) Third level • At high propeller RPM, noise at the blade passing Fourth level frequency (BPF) is the dominant noise Fifth level 2400rpm, 80Hz, 93.3dB 2400rpm, 120Hz, 91dB [1] D.Miljkovic, M.Maletic, M.Obad, 2007. “Comparative Investigation of Aircraft Interior Noise Properties” , 3 rd Congress of the Alps-Adria Acoustics Association. [2] D.Miljkovic, J. Ivosevic, T.Bucak, 2012. “Two vs Three Blade Propeller – Cockpit Noise Comparison ”, 5 th Congress of the Alps-Adria Acoustics Association. 5 Slide 5

Propeller Basics Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 6 Slide 6

Propeller Basics Click to edit Master title style http://static.thisdayinaviation.com Click to edit Master text styles Second level Third level Fourth level Fifth level [3] J.E. Marte, D.w. Kurtz, 1970. “A Review of Aerodynamic Noise From Propellers, Rotors, and Lift Fans ”, NASA CR107568. [4] E.L. Chuan-Tau, J. Roskam, 2008. “ Airplane Aerodynamics and Performance ”, DARcorporation, USA. 7 Slide 7

Propeller Basics Click to edit Master title style https://www.nas.nasa.gov/SC12/demos/demo1.html Click to edit Master text styles Second level Third level Fourth level Fifth level http://www.aircav.com [3] J.E. Marte, D.w. Kurtz, 1970. “A Review of Aerodynamic Noise From Propellers, Rotors, and Lift Fans ”, NASA CR107568. [4] E.L. Chuan-Tau, J. Roskam, 2008. “ Airplane Aerodynamics and Performance ”, DARcorporation, USA. 8 Slide 8

Propeller Basics Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level [3] J.E. Marte, D.w. Kurtz, 1970. “A Review of Aerodynamic Noise From Propellers, Rotors, and Lift Fans ”, NASA CR107568. [4] E.L. Chuan-Tau, J. Roskam, 2008. “ Airplane Aerodynamics and Performance ”, DARcorporation, USA. 9 Slide 9

Propeller Basics Click to edit Master title style Click to edit Master text styles Second level Third level D Fourth level Fifth level v a 10 Slide 10

Propeller Basics [4][5] Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level [4] E.L. Chuan-Tau, J. Roskam, 2008. “ Airplane Aerodynamics and Performance ”, DARcorporation, USA. [5] F.E. Weick, 1930. “ Aircraft Propeller Design”, McGraw-Hill Book Company, USA 11 Slide 11

Simulation Methodology Click to edit Master title style The following was employed for this aeroacoustics study of the NASA SR-2 propeller 1. Generation of propeller geometry, followed by meshing within the domain Click to edit Master text styles 2. Upon completion of volume meshing, simulation is setup to run steady state with Moving Second level Reference Frame (MRF) Third level 3. Converged steady solution is then used to calculate the propeller power coefficient, C p Fourth level 4. Calibration of blade angle through a series of steady state simulations at varied propeller Fifth level blade angle, so as to match the predicted C p to the experimental C p 5. Upon calibration of the propeller blade angle, the simulation is then setup to run transiently with rigid body motion (sliding mesh) 6. The transient simulation is allowed to run for at least 10 propeller rotations to transit to a “steady” condition 7. Simulation is subsequently ran for a further 10 propeller rotations in order to record the pressure signal at the receivers 8. Pressure data recorded at the receivers processed to acquire sound pressure levels at the blade passing frequency (BPF) 12 Slide 12

Simulation Methodology Click to edit Master title style The following was employed for the physics modelling Click to edit Master text styles Steady State Simulation Transient Simulation Second level Steady Implicit unsteady Third level Segregated flow Segregated flow Fourth level Fifth level Ideal gas Ideal gas Segregated fluid enthalpy Segregated fluid enthalpy K- Ω SST Detached Eddy Simulation (K- Ω based) All Y+ wall treatment All Y+ wall treatment Cell quality remediation Cell quality remediation • Time step of 2.5e-5 seconds utilized to capture propeller rotation rate of 1° per time-step • 10 inner iterations for convergence of time-step 13 Slide 13

Generation of SR-2 propeller CAD [6] Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level [6] G.L.Stefko, R.J.Jeracki, 1985. “ Wind Tunnel Results of Advanced High Speed Propellers in Takeoff, Climb & Landing Operating Regimes ”, AIAA-85-1259. 14 Slide 14

Generation of SR-2 propeller CAD Click to edit Master title style delta β Corrected β r/R t/b ¡Corrected b/D ¡Corrected CLD ¡Corrected 0.239 0.19804 0.14485 -­‑0.23259 23.325 82.325 0.250 0.16342 0.14521 -­‑0.18897 22.585 81.585 Click to edit Master text styles Root portion (r/R from 0.239 0.275 0.12503 0.14557 -­‑0.10860 20.851 79.851 to 0.367) of propeller utilized Second level 0.300 0.10005 0.14629 -­‑0.03922 18.979 77.979 modified NACA 65 series 0.325 0.08589 0.14702 0.00820 17.219 76.219 Third level airfoil profiles having a circular 0.350 0.07471 0.14774 0.04465 15.465 74.465 Fourth level 0.367 0.06898 0.14810 0.06392 14.355 73.355 arc mean camber line [7][8] Fifth level 0.449 0.05097 0.14990 0.12993 10.098 69.098 0.5 0.04377 0.15061 0.15401 8.185 67.185 0.55 0.03762 0.15058 0.16679 6.394 65.394 0.6 0.03279 0.14981 0.16665 4.726 63.726 0.65 0.02907 0.14831 0.16096 3.058 62.058 0.7 0.02625 0.14680 0.14789 1.483 60.483 0.75 0.02364 0.14529 0.12190 0.000 59.000 NACA 16 series airfoil 0.8 0.02234 0.14268 0.10144 -­‑1.405 57.595 profiles [4] are utilized at the 0.85 0.02083 0.13764 0.07729 -­‑3.243 55.757 outer portion (r/R from 0.449 0.9 0.02080 0.12896 0.05195 -­‑5.188 53.812 to 1.0) of the propeller. 0.95 0.02040 0.11304 0.02530 -­‑6.394 52.606 0.96 0.02003 0.10789 0.01973 -­‑6.600 52.400 0.97 0.02002 0.10051 0.01417 -­‑6.765 52.235 0.98 0.02002 0.09201 0.00860 -­‑6.935 52.065 0.99 0.02001 0.07792 0.00303 -­‑7.044 51.956 1 0.02000 0.05824 -­‑0.00582 -­‑7.083 51.917 [4] E.L. Chuan-Tau, J. Roskam, 2008. “ Airplane Aerodynamics and Performance ”, DARcorporation, USA. [7] N.A. Cumpsty, 1989. “ Compressor Aerodynamics”, Longman Scientific & Technical, USA [8] D.C. Mikkelson, B.J. Blaha, G.A. Mitchell, J.E. Wikete, 1977. “ Design and Performance of Energy Efficient Propellers for Mach 0.8 Cruise ”, NASA TM X-73612 . 15 Slide 15

Generation of SR-2 propeller CAD Click to edit Master title style Fine tuning of digitalized data a) Blade thickness ratio, t/b was fine-tuned, knowing t/b at tip is 2% [8] Click to edit Master text styles b) Blade width ratio, b/D was fine-tuned, knowing blade activity factor AF=203 [8][9] Second level Third level Fourth level Fifth level c) Blade design lift coefficient, C LD was fine-tuned, knowing integrated design lift coefficient C LI = 0.081 [8][9] d) Change in blade angle with respect to that at 75% blade radius, Δ β was fine-tuned, knowing Δ β =0 at 0.75 r/R [8][9] [8] D.C. Mikkelson, B.J. Blaha, G.A. Mitchell, J.E. Wikete, 1977. “ Design and Performance of Energy Efficient Propellers for Mach 0.8 Cruise ”, NASA TM X-73612. [9] G.L. Stefko, R.J. Jeracki, 1985. “ Wind-Tunnel Results of Advanced High-Speed Propellers at Takeoff, Climb, and Landing Mach Numbers ”, NASA TM 87030. 16 Slide 16

Generation of SR-2 propeller CAD Slide 17