Shi, Weichao

English

World Maritime University

Biomimetic improvement of hydrodynamic performance  for tidal turbines Reporter:       Weichao Shi  Position:        Research assistant and PhD candidate Supervisors:  Prof. Mehmet Atlar & Dr. Rosemary Norman Presentation layout Ø  Introduction Ø  Aims and objectives Ø  Study for a representative hydrofoil  Ø  Study for tidal turbine models Ø  Conclusions “Humpback Whale” q  Giant marine mammal, 12~16m long q  Distinctive body shape, with unusually long fins Unusually long fins with leading-edge tubercles? Introduction-Understandings of the Unusual behaviour  Bubble net hunting: 1.  Swim circularly to drive ton of fish into a small circular zone 2.  Produce bubbles as a bubble net to prevent the fish from escaping 3.  All together open mouths to swallow tones of fish Replica of humpback whale fins  •  Test in wind tunnel  by Miklosovic et. al.  •  Increase lift  •  Decrease drag •  Delay the stall angle o  Open circle: the foil with leading-edge tubercles •  Closed circle: the smooth foil Introduction-Understandings of the Unusual behaviour  Wind	turbines	Sur-oards	Rudders	 Fans	Introduction-Applications	of	Tubercles	Introduction-Applications of Tubercles q Typical 3D foil application q Better efficiency q Better starting performance q More economical q More robust §  Objectives §  Stage I _ Hydrofoil study: Apply tubercle technology to hydrofoil to achieve basic understandings for the tubercles §  Stage II _ Tidal Turbine study: Redesign, optimise and test turbines with tubercles Aims and Objectives §  Aims §  To explore the feasibility of applying biomimetics via leading-edge tubercles to enhance the performance of tidal turbines. Experiment for a representative hydrofoil  Hydrofoil Based on a Tidal Turbine Blade•  a same chord length distribution •  a constant pitch angle 3D printed leading-edge sections •  4 wavy leading-edge sections •  4 smooth leading-edge sections Support base part •  CNC machined •  Carbon fibre reinforced plastic Configurations Labels Figures All with smooth leading-edge modules 0000 All with sinusoidal leading-edge modules 1111 One smooth leading-edge module at the root and the other three sinusoidal modules 0111 Two smooth leading-edge modules at the root and the other two sinusoidal modules 0011 Three smooth leading-edge modules at the root and the other one sinusoidal module 0001 Experiment for a representative hydrofoil  Experiment for a representative hydrofoil  q  The performance of the hydrofoil can be dramatically enhanced by the tubercles q  The lift coefficients were increased greatly q  The drag coefficients were maintained or lowered  q  Foil with the shortest tubercle application length (1/4 of the span) at tip region overall displayed the best performance. 	0.380.761.141.520.000.280.560.840 5 10 15 20 25 30 35 400.05.711.417.1  CL 0000_3 1111_3 0001_3Comparison of different configurations CD CL/CDANGLE OF ATTACK, AOA (Deg)Experiment for tidal turbine models  q  Three pitch adjustable model tidal turbines are currently under experimental test. q  Hydrodynamic Performance test: power coefficients and drag coefficients can be achieved to evaluate the efficiency of the turbine models. V TSR RPM Pitch angleTunnel pressureCav Re(m/s) (o) (mmhg) (0.7r) (0.7r)2 0.5 ~ 8 47 ~ 763 0 850 48.534 ~ 1.684 0.76E+05 ~ 2.24E+052 0.5 ~ 8 47 ~ 763 +4 850 48.534 ~ 1.684 0.76E+05 ~ 2.24E+052 0.5 ~ 8 47 ~ 763 +8 850 48.534 ~ 1.684 0.76E+05 ~ 2.24E+053 0.5 ~ 8 71 ~ 1145 0 850 21.571 ~ 0.748 1.15E+05 ~ 3.36E+053 0.5 ~ 8 71 ~ 1145 +4 850 21.571 ~ 0.748 1.15E+05 ~ 3.36E+053 0.5 ~ 8 71 ~ 1145 +8 850 21.571 ~ 0.748 1.15E+05 ~ 3.36E+054 0.5 ~ 8 95 ~ 1527 0 850 12.134 ~ 0.421 1.53E+05 ~ 4.48E+054 0.5 ~ 8 95 ~ 1527 +4 850 12.134 ~ 0.421 1.53E+05 ~ 4.48E+054 0.5 ~ 8 95 ~ 1527 +8 850 12.134 ~ 0.421 1.53E+05 ~ 4.48E+05Effect of blade pitch angle q  Three different pitch angles was tested: q  0 degree; q  +4 degree; q  +8 degree q  Tests under 2m/s q  Reference turbine §  Based on the test results the reference turbine had the best efficiency over the widest TSR when the blade pitch angle was set to +4o.  §  When the blade pitch angle was set to 0o the force on the blade contributed more in the thrust. §  For the case +8o the increased pitch angle resulted in a reduced angle of attack and hence lower thrust force on the turbine but also lower power. Effect of different leading-edge tubercle profiles §  Leading-edge tubercles can greatly enhance the performance on the lower range of TSRs, while the blade is operating under stall conditions.§  For the lower pitch angles, the improvement caused by the leading-edge tubercles is higher than the one for the higher pitch angle.§  The application of the leading edge tubercle concept does not compromise the maximum power coefficientCavitation observation and Noise measurement •  Effect on cavitation: •  Limit the cavitation in the crest region •  Trigger cavitation inception earlier Cavitation observation and Noise measurement •  Noise level can be lowered down because of the constrained cavitation development during cloud cavitation •  During the normal conditions, the performance is similar to the reference turbine Hydrofoil study •  Optimisation study for the design of tubercles  •  Experimental study on a tidal turbine blade based hydrofoil •  The performance of the hydrofoil can be dramatically enhanced by the tubercles Tidal turbine study •  The models with the leading-edge tubercles had a better performance in the lower tip speed ratios (TSRs) where the turbine blades were working under the stall conditions. •  The biomimetic concept did not compromise the maximum power coefficient value of the turbine but shifted the distribution of the coefficient over TSR Conclusions Leading-edge tubercles are very effective! Future Scope §  Potential application on marine propellers: §  High speed propellers §  CPPs §  Tip loaded propellers §  Ducted propellers §  Marine related applications ?	 Thank you! Q&A  

Biomimetic improvement of hydrodynamic performance for tidal turbines

https://commons.wmu.se/cgi/viewcontent.cgi?article=1050&amp;context=marener_conference

Biomimetic improvement of hydrodynamic performance for tidal turbines

Abstract

Similar works

Full text

Available Versions

World Maritime University