Numerical and Experimental Comparison of Surface Pressures around a Scaled Ship Wind-Assisted Propulsion System
Significant legislative changes are set to revolutionise the commercial shipping industry. Upcoming emissions restrictions will force operators to look at technologies that can improve the efficiency of their vessels -reducing fuel consumption and emissions. A device which may help in this challenge is the Ship Wind-Assisted Propulsion system (SWAP), an actively controlled aerofoil mounted vertically on the deck of a ship. The device functions in a similar manner to a sail on a yacht, whereby the aerodynamic forces generated by the sail reach an equilibrium with the hydrodynamic forces on the hull and a forward velocity results. Numerical and experimental testing of the SWAP device is presented in this study. Circulation control takes the form of a co-flow jet aerofoil, utilising both blowing from the leading edge and suction from the trailing edge. A jet at the leading edge uses the Coanda effect to energise the boundary layer in order to delay flow separation and create high lift with low drag. The SWAP concept has been originated by the research and development team at SMAR Azure Ltd. The device will be retrofitted to existing ships so that a component of the aerodynamic forces acts forward and partially reduces the reliance on existing propulsion systems. Wind tunnel tests have been carried out at the de Havilland wind tunnel at the University of Glasgow on a 1:20 scale model of this system. The tests aim to understand the airflow characteristics around the aerofoil and investigate the approximate lift and drag coefficients that an early iteration of the SWAP device may produce. The data exhibits clear trends of increasing lift as injection momentum increases, with critical flow attachment points being identified at specific combinations of jet momentum coefficient, Cµ, and angle of attack, AOA. Various combinations of flow conditions were tested, with the jet momentum coefficient ranging from 0 to 0.7 and the AOA ranging from 0° to 35°. The Reynolds number across the tested conditions ranged from 80,000 to 240,000. Comparisons between 2D computational fluid dynamics (CFD) simulations and the experimental data are presented for multiple Reynolds-Averaged Navier-Stokes (RANS) turbulence models in the form of normalised surface pressure comparisons. These show good agreement for most of the tested cases. However, certain simulation conditions exhibited a well-documented shortcoming of RANS-based turbulence models for circulation control flows and over-predicted surface pressures and lift coefficient for fully attached flow cases. Work must be continued in finding an all-encompassing modelling approach which predicts surface pressures well for all combinations of jet injection momentum and AOA.
[1] United Nations. (2018). Oceans and the Law of the Sea. Available: http://www.un.org/en/sections/issues-depth/oceans-and-law-sea/index.html. Last accessed 20th Jul 2018. W.-K. Chen, Linear Networks and Systems. Belmont, CA: Wadsworth, 1993, pp. 123–135.
[2] Organization, I.M. Sulphur 2020 – Cutting Sulphur Oxide Emissions. 2018 (cited 2018 6th June); Available from: http://www.imo.org/ en/MediaCentre/HotTopics/Pages/Sulphur-2020.aspx.
[3] Organization, I.M. UN body adopts climate change strategy for shipping. 2018 (cited 2018 5th June); Available from: http://www. imo.org/en/MediaCentre/PressBriefings/Pages/06GHGinitialstrategy.aspx
[4] Register, L.s., Low carbon pathways 2050, I. Sustainability, Editor. 2016: Online
[5] Shukla, P. C., Ghosh, K. (2009). Revival of the Modern Wing Sails for the Propulsion of Commercial Ships. World Academy of Science, Engineering and Technology International Journal of Physical and Mathematical Sciences. 3 (3)
[6] Smith, T. et al. (2013). Analysis techniques for evaluating the fuel savings associated with wind assistance. Low Carbon Shipping Conference.
[7] Carter, R., Boat remains and maritime trade in the Persian Gulf during the sixth and fifth millennia BC. Antiquity, 2006. 80(307): p. 52-63.
[8] Carter, W. E., & Carter, M. S. (2010). The Age of Sail: A Time when the Fortunes of Nations and Lives of Seamen Literally Turned with the Winds Their Ships Encountered at Sea. Journal of Navigation, 63(04), 717–731. doi:10.1017/s0373463310000263
[9] Michael Lang, The Journal of Modern History, Vol. 78, No. 4 (December 2006), pp. 899-931, Published by: The University of Chicago Press, DOI: 10.1086/511251, https://www.jstor.org/stable/10.1086/511251
[10] Chrzanowski, I. (1980). Shipping in the 1980s—a future with uncertainty? Maritime Policy & Management, 7(1), 1–8. doi:10.1080/03088838000000048
[11] Viola, I. M., Sacher, M., Xu, J., & Wang, F. (2015). A numerical method for the design of ships with wind-assisted propulsion. Ocean Engineering, 105, 33–42. doi: 10.1016/j.oceaneng.2015.06.009
[12] Copuroglu, H. I., & Pesman, E. (2018). Analysis of Flettner Rotor ships in beam waves. Ocean Engineering, 150, 352–362. doi:10.1016 /j. oceaneng.2018.01.004
[13] Searcy, T. (2017). Harnessing the wind: A case study of applying Flettner rotor technology to achieve fuel and cost savings for Fiji’s domestic shipping industry. Marine Policy, 86, 164–172. doi:10.1016/ j.marpol.2017.09.020
[14] Takayama, S., & Aoki, K. (2005). Flow characteristics around a rotating grooved circular cylinder with grooved of different depths. Journal of Visualization, 8(4), 295–303. doi:10.1007/bf03181548
[15] THOM, A. 1926 The pressure round a cylinder rotating in an air current. ARC R. & M. 1082
[16] Prandtl, L. (1925). Application of the "Magnus Effect" to the Wind Propulsion of Ships. Die Naturwissenschaft. 13, p93-108.
[17] Craft, T., Johnson, N., & Launder, B. (2013). Back to the Future? A Re-examination of the Aerodynamics of Flettner-Thom Rotors for Maritime Propulsion. Flow, Turbulence and Combustion, 92(1-2), 413–427. doi:10.1007/s10494-013-9486-4
[18] Suominen, T, 2015, Rotor pilot project on M/S Estraden of Bore fleet, Bachelor of Marine Technology, Satakunta University of Applied Sciences
[19] Airbus. (2018). High-flying Airbus technology comes down to Earth for use on ships. Available: https://www.airbus.com/newsroom/news /en/2018/09/high-flying-airbus-technology-comes-down-to-earth-for-use-on-shi.html. Last accessed 12th Sep 2018
[20] Kiteboat. (2018). Kiteboat Project. Available: https://project.kiteboat. com/design/. Last accessed 12th Sep 2018
[21] Kukner et al. (2016). Renewable Energy Options and an Assessment of Wind-Based Propulsion Systems for Small Crafts. Naval Academy Scientific Bulletin. 19
[22] Naaijen, Peter, and Vincent Koster. "Performance of auxiliary wind propulsion for merchant ships using a kite." 2nd International Conference on Marine Research and Transportation. 2007
[23] Traut, M., Gilbert, P., Walsh, C., Bows, A., Filippone, A., Stansby, P., & Wood, R. (2014). Propulsive power contribution of a kite and a Flettner rotor on selected shipping routes. Applied Energy, 113, 362–372. doi: 10.1016/j.apenergy.2013.07.026
[24] Yoshimura, Yasuo. (2002). A Prospect of Sail-Assisted Fishing Boats. Fisheries Science. 2, p1815-1818
[25] Charrier, B., Constans, J., Cousteau, J.-Y., Daïf, A., Malavard, L., & Quinio, J.-L. (1985). Fondation Cousteau and windship propulsion 1980 – 1985 system Cousteau - Pechiney. Journal of Wind Engineering and Industrial Aerodynamics, 20(1-3), 39–60. doi:10.1016/0167-6105(85)90011-x
[26] Hcini, C., Abidi, E., Kamoun, B., & Afungchui, D. (2016). Numerical prediction for the aerodynamic performance of Turbosail type wind turbine using a vortex model. Energy, 109, 287–293. doi: 10.1016/j.energy.2016.04.113
[27] Guerri, O.; Liberge, E.; Hamdouni, A. (2016). Numerical Simulation of the Turbulent Flow around an Oval-Sail. Journal of Applied Fluid Mechanics. 9 (4), p2009-2023
[28] Konstantinos, K. et al (2018). Foundations of Circulation Control Based Small-Scale Unmanned Aircraft: A Comprehensive Methodology from Concept to Design and Experimental Testing: Springer International Publishing
[29] Imants Reba. (1966). Applications of the Coanda Effect. Scientific American. 214, pp. 84-93.
[30] Rodman, L.C., Wood, N.J. and Roberts, L., 1989. Experimental investigation of straight and curved annular wall jets. AIAA journal, 27(8), pp.1059-1067.
[31] Newman, B.G., 1961. The deflection of plane jets by adjacent boundaries-Coanda effect. Boundary layer and flow control.
[32] Allery, C., Guerin, S., Hamdouni, A., & Sakout, A. (2004). Experimental and numerical POD study of the Coanda effect used to reduce self-sustained tones. Mechanics Research Communications, 31(1), 105–120. doi: 10.1016/j.mechrescom.2003.08.003
[33] Abdul Hamid, M. F. (2011). Numerical Simulation and Analysis of Coanda Effect Circulation Control for Wind Turbine Application Considerations IIUM Engineering Journal, 12(3). Retrieved from http://journals.iium.edu.my/ejournal/index.php/iiumej/article/view/68
[34] Storm, T., & Marshall, D. (2010). Assessing the v2-f Turbulence Models for Circulation Control Applications. 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition. doi:10.2514/6.2010-1054
[35] Rumsey, C., & Nishino, T. (2011). Numerical Study Comparing RANS and LES Approaches on a Circulation Control Airfoil. 49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition. doi:10.2514/6.2011-1179
[36] Swanson, R., Rumsey, C., & Anders, S. (2005). Progress Towards Computational Method for Circulation Control Airfoils. 43rd AIAA Aerospace Sciences Meeting and Exhibit. doi:10.2514/6.2005-89
[37] Swanson, R.C., Rumsey, C.L. and Anders, S.G., 2006. Aspects of numerical simulation of circulation control airfoils. Progress in astronautics and aeronautics, 214, p.469
[38] Zha, G.-C., and Paxton, D. C., “A Novel Flow Control Method for Airfoil Performance Enhancement Using Co-Flow Jet,” Applications of Circulation Control Technologies, edited by Joslin, R. D. and Jones, G.S., Progress in Astronautics and Aeronautics, Vol. 214, AIAA, Reston, VA, 2006, pp. 293–314, Chap. 10
[39] Zha, G., Gao, W., & Paxton, C. D. (2007). Jet Effects on Coflow Jet Airfoil Performance. AIAA Journal, 45(6), 1222–1231. doi:10.2514/1.23995
[40] Xu, H., Xing, S. and Ye, Z., 2015. Numerical simulation of the effect of a co-flow jet on the wind turbine airfoil aerodynamic characteristics. Procedia Engineering, 126, pp.706-710.
[41] Skinner, S.N. and Zare-Behtash, H., 2017. Semi-span wind tunnel testing without conventional peniche. Experiments in Fluids, 58(12), p.163.
[42] Barlow, J.B., Rae Jr, W.H. and Pope, A., 2015. Low speed wind tunnel testing. INCAS Bulletin, 7(1), p.133.
[43] Shankara, P. and Snyder, D., 2012, June. Numerical simulation of high lift trap wing using STAR-CCM+. In 30th AIAA Applied Aerodynamics Conference (p. 2920).
[44] Gualtieri, C., Jiménez, P.L. and Rodríguez, J.M., 2009, August. A comparison among turbulence modelling approaches in the simulation of a square dead zone. In Proceedings of the 19th Canadian Hydrotechnical Conference, Vancouver, BC, Canada (pp. 9-14).
[45] Yoon, G.H., 2016. Topology optimization for turbulent flow with Spalart–Allmaras model. Computer Methods in Applied Mechanics and Engineering, 303, pp.288-311.
[46] Siemens (2018). STAR-CCM+ Documentation Version 13.02: Siemens PLM Software
[47] Shur, M., Strelets, M., Travin, A. and Spalart, P., 1997. Turbulence modeling in rotating and curved channels-assessment of the Spalart-Shur correction term. In 36th AIAA Aerospace Sciences Meeting and Exhibit (p. 325).
[48] Asnaghi, A., Svennberg, U. and Bensow, R.E., 2019. Evaluation of curvature correction methods for tip vortex prediction in SST k− ω turbulence model framework. International Journal of Heat and Fluid Flow, 75, pp.135-152.
[49] Idelchik, I.E., 2017. Flow resistance: a design guide for engineers. Routledge.
[50] Wang, B., Haddoukessouni, B., Levy, J. and Zha, G.C., 2008. Numerical investigations of injection-slot-size effect on the performance of coflow jet airfoils. Journal of Aircraft, 45(6), pp.2084-2091.
[51] Wilde, D., 2010. Analysis of Curvature Effects on Boundary Layer Separation and Turbulence Model Accuracy for Circulation Control Applications.
[1] United Nations. (2018). Oceans and the Law of the Sea. Available: http://www.un.org/en/sections/issues-depth/oceans-and-law-sea/index.html. Last accessed 20th Jul 2018. W.-K. Chen, Linear Networks and Systems. Belmont, CA: Wadsworth, 1993, pp. 123–135.
[2] Organization, I.M. Sulphur 2020 – Cutting Sulphur Oxide Emissions. 2018 (cited 2018 6th June); Available from: http://www.imo.org/ en/MediaCentre/HotTopics/Pages/Sulphur-2020.aspx.
[3] Organization, I.M. UN body adopts climate change strategy for shipping. 2018 (cited 2018 5th June); Available from: http://www. imo.org/en/MediaCentre/PressBriefings/Pages/06GHGinitialstrategy.aspx
[4] Register, L.s., Low carbon pathways 2050, I. Sustainability, Editor. 2016: Online
[5] Shukla, P. C., Ghosh, K. (2009). Revival of the Modern Wing Sails for the Propulsion of Commercial Ships. World Academy of Science, Engineering and Technology International Journal of Physical and Mathematical Sciences. 3 (3)
[6] Smith, T. et al. (2013). Analysis techniques for evaluating the fuel savings associated with wind assistance. Low Carbon Shipping Conference.
[7] Carter, R., Boat remains and maritime trade in the Persian Gulf during the sixth and fifth millennia BC. Antiquity, 2006. 80(307): p. 52-63.
[8] Carter, W. E., & Carter, M. S. (2010). The Age of Sail: A Time when the Fortunes of Nations and Lives of Seamen Literally Turned with the Winds Their Ships Encountered at Sea. Journal of Navigation, 63(04), 717–731. doi:10.1017/s0373463310000263
[9] Michael Lang, The Journal of Modern History, Vol. 78, No. 4 (December 2006), pp. 899-931, Published by: The University of Chicago Press, DOI: 10.1086/511251, https://www.jstor.org/stable/10.1086/511251
[10] Chrzanowski, I. (1980). Shipping in the 1980s—a future with uncertainty? Maritime Policy & Management, 7(1), 1–8. doi:10.1080/03088838000000048
[11] Viola, I. M., Sacher, M., Xu, J., & Wang, F. (2015). A numerical method for the design of ships with wind-assisted propulsion. Ocean Engineering, 105, 33–42. doi: 10.1016/j.oceaneng.2015.06.009
[12] Copuroglu, H. I., & Pesman, E. (2018). Analysis of Flettner Rotor ships in beam waves. Ocean Engineering, 150, 352–362. doi:10.1016 /j. oceaneng.2018.01.004
[13] Searcy, T. (2017). Harnessing the wind: A case study of applying Flettner rotor technology to achieve fuel and cost savings for Fiji’s domestic shipping industry. Marine Policy, 86, 164–172. doi:10.1016/ j.marpol.2017.09.020
[14] Takayama, S., & Aoki, K. (2005). Flow characteristics around a rotating grooved circular cylinder with grooved of different depths. Journal of Visualization, 8(4), 295–303. doi:10.1007/bf03181548
[15] THOM, A. 1926 The pressure round a cylinder rotating in an air current. ARC R. & M. 1082
[16] Prandtl, L. (1925). Application of the "Magnus Effect" to the Wind Propulsion of Ships. Die Naturwissenschaft. 13, p93-108.
[17] Craft, T., Johnson, N., & Launder, B. (2013). Back to the Future? A Re-examination of the Aerodynamics of Flettner-Thom Rotors for Maritime Propulsion. Flow, Turbulence and Combustion, 92(1-2), 413–427. doi:10.1007/s10494-013-9486-4
[18] Suominen, T, 2015, Rotor pilot project on M/S Estraden of Bore fleet, Bachelor of Marine Technology, Satakunta University of Applied Sciences
[19] Airbus. (2018). High-flying Airbus technology comes down to Earth for use on ships. Available: https://www.airbus.com/newsroom/news /en/2018/09/high-flying-airbus-technology-comes-down-to-earth-for-use-on-shi.html. Last accessed 12th Sep 2018
[20] Kiteboat. (2018). Kiteboat Project. Available: https://project.kiteboat. com/design/. Last accessed 12th Sep 2018
[21] Kukner et al. (2016). Renewable Energy Options and an Assessment of Wind-Based Propulsion Systems for Small Crafts. Naval Academy Scientific Bulletin. 19
[22] Naaijen, Peter, and Vincent Koster. "Performance of auxiliary wind propulsion for merchant ships using a kite." 2nd International Conference on Marine Research and Transportation. 2007
[23] Traut, M., Gilbert, P., Walsh, C., Bows, A., Filippone, A., Stansby, P., & Wood, R. (2014). Propulsive power contribution of a kite and a Flettner rotor on selected shipping routes. Applied Energy, 113, 362–372. doi: 10.1016/j.apenergy.2013.07.026
[24] Yoshimura, Yasuo. (2002). A Prospect of Sail-Assisted Fishing Boats. Fisheries Science. 2, p1815-1818
[25] Charrier, B., Constans, J., Cousteau, J.-Y., Daïf, A., Malavard, L., & Quinio, J.-L. (1985). Fondation Cousteau and windship propulsion 1980 – 1985 system Cousteau - Pechiney. Journal of Wind Engineering and Industrial Aerodynamics, 20(1-3), 39–60. doi:10.1016/0167-6105(85)90011-x
[26] Hcini, C., Abidi, E., Kamoun, B., & Afungchui, D. (2016). Numerical prediction for the aerodynamic performance of Turbosail type wind turbine using a vortex model. Energy, 109, 287–293. doi: 10.1016/j.energy.2016.04.113
[27] Guerri, O.; Liberge, E.; Hamdouni, A. (2016). Numerical Simulation of the Turbulent Flow around an Oval-Sail. Journal of Applied Fluid Mechanics. 9 (4), p2009-2023
[28] Konstantinos, K. et al (2018). Foundations of Circulation Control Based Small-Scale Unmanned Aircraft: A Comprehensive Methodology from Concept to Design and Experimental Testing: Springer International Publishing
[29] Imants Reba. (1966). Applications of the Coanda Effect. Scientific American. 214, pp. 84-93.
[30] Rodman, L.C., Wood, N.J. and Roberts, L., 1989. Experimental investigation of straight and curved annular wall jets. AIAA journal, 27(8), pp.1059-1067.
[31] Newman, B.G., 1961. The deflection of plane jets by adjacent boundaries-Coanda effect. Boundary layer and flow control.
[32] Allery, C., Guerin, S., Hamdouni, A., & Sakout, A. (2004). Experimental and numerical POD study of the Coanda effect used to reduce self-sustained tones. Mechanics Research Communications, 31(1), 105–120. doi: 10.1016/j.mechrescom.2003.08.003
[33] Abdul Hamid, M. F. (2011). Numerical Simulation and Analysis of Coanda Effect Circulation Control for Wind Turbine Application Considerations IIUM Engineering Journal, 12(3). Retrieved from http://journals.iium.edu.my/ejournal/index.php/iiumej/article/view/68
[34] Storm, T., & Marshall, D. (2010). Assessing the v2-f Turbulence Models for Circulation Control Applications. 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition. doi:10.2514/6.2010-1054
[35] Rumsey, C., & Nishino, T. (2011). Numerical Study Comparing RANS and LES Approaches on a Circulation Control Airfoil. 49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition. doi:10.2514/6.2011-1179
[36] Swanson, R., Rumsey, C., & Anders, S. (2005). Progress Towards Computational Method for Circulation Control Airfoils. 43rd AIAA Aerospace Sciences Meeting and Exhibit. doi:10.2514/6.2005-89
[37] Swanson, R.C., Rumsey, C.L. and Anders, S.G., 2006. Aspects of numerical simulation of circulation control airfoils. Progress in astronautics and aeronautics, 214, p.469
[38] Zha, G.-C., and Paxton, D. C., “A Novel Flow Control Method for Airfoil Performance Enhancement Using Co-Flow Jet,” Applications of Circulation Control Technologies, edited by Joslin, R. D. and Jones, G.S., Progress in Astronautics and Aeronautics, Vol. 214, AIAA, Reston, VA, 2006, pp. 293–314, Chap. 10
[39] Zha, G., Gao, W., & Paxton, C. D. (2007). Jet Effects on Coflow Jet Airfoil Performance. AIAA Journal, 45(6), 1222–1231. doi:10.2514/1.23995
[40] Xu, H., Xing, S. and Ye, Z., 2015. Numerical simulation of the effect of a co-flow jet on the wind turbine airfoil aerodynamic characteristics. Procedia Engineering, 126, pp.706-710.
[41] Skinner, S.N. and Zare-Behtash, H., 2017. Semi-span wind tunnel testing without conventional peniche. Experiments in Fluids, 58(12), p.163.
[42] Barlow, J.B., Rae Jr, W.H. and Pope, A., 2015. Low speed wind tunnel testing. INCAS Bulletin, 7(1), p.133.
[43] Shankara, P. and Snyder, D., 2012, June. Numerical simulation of high lift trap wing using STAR-CCM+. In 30th AIAA Applied Aerodynamics Conference (p. 2920).
[44] Gualtieri, C., Jiménez, P.L. and Rodríguez, J.M., 2009, August. A comparison among turbulence modelling approaches in the simulation of a square dead zone. In Proceedings of the 19th Canadian Hydrotechnical Conference, Vancouver, BC, Canada (pp. 9-14).
[45] Yoon, G.H., 2016. Topology optimization for turbulent flow with Spalart–Allmaras model. Computer Methods in Applied Mechanics and Engineering, 303, pp.288-311.
[46] Siemens (2018). STAR-CCM+ Documentation Version 13.02: Siemens PLM Software
[47] Shur, M., Strelets, M., Travin, A. and Spalart, P., 1997. Turbulence modeling in rotating and curved channels-assessment of the Spalart-Shur correction term. In 36th AIAA Aerospace Sciences Meeting and Exhibit (p. 325).
[48] Asnaghi, A., Svennberg, U. and Bensow, R.E., 2019. Evaluation of curvature correction methods for tip vortex prediction in SST k− ω turbulence model framework. International Journal of Heat and Fluid Flow, 75, pp.135-152.
[49] Idelchik, I.E., 2017. Flow resistance: a design guide for engineers. Routledge.
[50] Wang, B., Haddoukessouni, B., Levy, J. and Zha, G.C., 2008. Numerical investigations of injection-slot-size effect on the performance of coflow jet airfoils. Journal of Aircraft, 45(6), pp.2084-2091.
[51] Wilde, D., 2010. Analysis of Curvature Effects on Boundary Layer Separation and Turbulence Model Accuracy for Circulation Control Applications.
@article{"International Journal of Mechanical, Industrial and Aerospace Sciences:79276", author = "James Cairns and Marco Vezza and Richard Green and Donald MacVicar", title = "Numerical and Experimental Comparison of Surface Pressures around a Scaled Ship Wind-Assisted Propulsion System", abstract = "Significant legislative changes are set to revolutionise the commercial shipping industry. Upcoming emissions restrictions will force operators to look at technologies that can improve the efficiency of their vessels -reducing fuel consumption and emissions. A device which may help in this challenge is the Ship Wind-Assisted Propulsion system (SWAP), an actively controlled aerofoil mounted vertically on the deck of a ship. The device functions in a similar manner to a sail on a yacht, whereby the aerodynamic forces generated by the sail reach an equilibrium with the hydrodynamic forces on the hull and a forward velocity results. Numerical and experimental testing of the SWAP device is presented in this study. Circulation control takes the form of a co-flow jet aerofoil, utilising both blowing from the leading edge and suction from the trailing edge. A jet at the leading edge uses the Coanda effect to energise the boundary layer in order to delay flow separation and create high lift with low drag. The SWAP concept has been originated by the research and development team at SMAR Azure Ltd. The device will be retrofitted to existing ships so that a component of the aerodynamic forces acts forward and partially reduces the reliance on existing propulsion systems. Wind tunnel tests have been carried out at the de Havilland wind tunnel at the University of Glasgow on a 1:20 scale model of this system. The tests aim to understand the airflow characteristics around the aerofoil and investigate the approximate lift and drag coefficients that an early iteration of the SWAP device may produce. The data exhibits clear trends of increasing lift as injection momentum increases, with critical flow attachment points being identified at specific combinations of jet momentum coefficient, Cµ, and angle of attack, AOA. Various combinations of flow conditions were tested, with the jet momentum coefficient ranging from 0 to 0.7 and the AOA ranging from 0° to 35°. The Reynolds number across the tested conditions ranged from 80,000 to 240,000. Comparisons between 2D computational fluid dynamics (CFD) simulations and the experimental data are presented for multiple Reynolds-Averaged Navier-Stokes (RANS) turbulence models in the form of normalised surface pressure comparisons. These show good agreement for most of the tested cases. However, certain simulation conditions exhibited a well-documented shortcoming of RANS-based turbulence models for circulation control flows and over-predicted surface pressures and lift coefficient for fully attached flow cases. Work must be continued in finding an all-encompassing modelling approach which predicts surface pressures well for all combinations of jet injection momentum and AOA.
", keywords = "CFD, circulation control, Coanda, wing sail, wind tunnel. ", volume = "13", number = "11", pages = "698-14", }
