Add power curve functionality #377
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- Until Firedrake issue #3368 is resolved
- Interested in scalar/vector/tensor not DOF structure - Also simplify to fs.value_shape - no need for ufl_element().value_shape
- If a power coefficient table is not provided, then behaviour defaults to the Martin-Short et al., 2015 equation as previously
- Fix the Thetis options for power curve functionality as well
| for i in range(len(cb_turbines_AR1500.variable_names)): | ||
| print_output(cb_turbines_AR1500.variable_names[i] + ': (' + str(cb_turbines_AR1500.get_turbine_coordinates[i][0]) | ||
| + ', ' + str(cb_turbines_AR1500.get_turbine_coordinates[i][1]) + ')') |
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| for i in range(len(cb_turbines_AR1500.variable_names)): | |
| print_output(cb_turbines_AR1500.variable_names[i] + ': (' + str(cb_turbines_AR1500.get_turbine_coordinates[i][0]) | |
| + ', ' + str(cb_turbines_AR1500.get_turbine_coordinates[i][1]) + ')') | |
| for i, name in enumerate(cb_turbines_AR1500.variable_names): | |
| print_output(f'{name}: ' '({cb_turbines_AR1500.get_turbine_coordinates[i][0]}, ' | |
| '{cb_turbines_AR1500.get_turbine_coordinates[i][1]})') |
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Not important, but these bla + ': (' + str(...) + ' , ' + str(...) + ') type of things are a little hard to parse so I prefer format strings there. Same in two more loops below.
thetis/turbines.py
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| class ConstantThrustTurbine(TidalTurbine): | ||
| def __init__(self, options, upwind_correction=False): | ||
| super().__init__(options, upwind_correction=upwind_correction) | ||
| self.C_T = options.thrust_coefficient | ||
| self.C_P = getattr(options, "power_coefficient", 0.5 * self.C_T * (1 + (1 - self.C_T) ** 0.5)) |
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It seems you are trying to make it such that if "power_coefficient" is not specified it uses the analytical formula (as before I guess). However "power_coefficient" will always be present in ConstantTidalTurbineOptions with a default value of 0.7. So if the user only sets the thrust coefficient, say to some low value of 0.5, then the power coefficient will still be set to 0.7. If you want to make setting of power_coefficient turbine optional - one way to do it would be to make it a PositiveFloat(None, allow_none=True, "explain default None in help") and then self.C_P = options.power_coefficient or 0.5 * self.C_T * (1 + (1 - self.C_T) ** 0.5)
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Yes, thank you! I've applied the same to the tabulated approach as well for consistency
thetis/turbines.py
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| # this assumes the velocity through the turbine does not change due to the support (is this correct?) | ||
| return 0.25*C_T*A_T*(1+sqrt(1-C_T))*uv3 | ||
| return 0.5*(physical_constants['rho0']/1000)*A_T*C_P*uv3 |
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This makes sense, but requires a comment. I presume we are outputting energy in kW then? Basically the random factor of a 1000 needs explaining. Also would be happy if you decide to change it to output in W instead (so we're consistently SI)
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Yes, I had kept it consistent with previously in case there was a reason for this. I agree with changing it to Watts. Inclusion of the density is necessary as most thrust and power curves expect it to be 1025-1026kg/m3, not 1000kg/m3.
thetis/options.py
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| thrust_coefficients = List([3.0], help='Table of thrust coefficients') | ||
| power_coefficients = List([2.7], help='Table of power coefficients') | ||
| thrust_speeds = List( | ||
| [0.8, 0.8], |
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It seems that the default values for these are wrong (were wrong already!) with speeds and coefficients swapped. Also they don't pass the new check that the list of thrust coefficients and speeds should be the same length.
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Thought they might have just been exaggerated to show the influence of the turbine more clearly, but this makes more sense.
- Farm power units to W (from kW) - Do not require C_P specification - Update print statement formatting
Adds the option to provide power curves alongside thrust curves. Previously the power coefficients would have been determined based on the thrust coefficients as per the Martin-Short et al., 2015 paper. However, if the power coefficient data is available, we will want to use it directly.
Also updated the tidal turbine array example to demonstrate how to use different turbine types, as that functionality had been added in #358 but not demonstrated.