National Laboratory of the Rockies (NLR) — Power Curve & Efficiency Modeling
Current status (TEAMER RFTS-15 with NLR):
Pterofin is currently collaborating with the U.S. Department of Energy’s National Laboratory of the Rockies (NLR, formerly NREL) through TEAMER RFTS-15 technical support to quantify and validate the performance of the Pterofin Skimmer. NLR’s team is well underway on a 3D modeling campaign designed to produce decision-grade outputs—most importantly a defensible power curve and clear efficiency trends across realistic flow conditions. This milestone bridges our earlier lab testing with rigorous, physics-based prediction so investors, partners, and future customers can evaluate the technology with confidence.
Background on technology:
The Pterofin Skimmer is a marine energy system designed to harness energy near the water surface using an oscillating hydrofoil. The foil oscillates about a driveshaft in a pendulum-like motion. Near the end of each swing, the foil also pitches about its spanwise axis so the leading edge remains oriented upstream in the relative flow. A counterbalance and control system regulate wing motion, and the powertrain converts oscillatory motion into single-direction rotation to drive a generator. The Skimmer is designed to perform in lower-flow environments and to operate in shallow or constrained deployment settings.
Background on problem being addressed:
Past work on the Skimmer combined experimental prototype testing with low-fidelity modeling. Prototype testing demonstrated the viability of the concept, but it limited the number of configurations and operating conditions that could be explored. Analytical modeling provided early estimates of performance, but it did not capture several important aspects of operation—such as induction effects, unsteady separation, and variable lift behavior—needed to predict output across a broad operating envelope. This project expands capability by simulating device performance across a wide range of parameters at higher levels of fidelity, revealing which configurations increase performance, which reduce loads or improve stability, and which design/control choices should be prioritized for further optimization.
Statement of intended outcomes and what metrics will be used:
The project’s intended outcomes are: (1) identify which geometric and operational parameters improve performance; (2) quantify performance for a defined set of design and operating conditions to support development of a power curve; and (3) estimate uncertainty by comparing mid-fidelity and high-fidelity modeling approaches. The following metrics will be evaluated: driveshaft torque and rotational speed, mechanical power, hydrofoil pitching torque, and overall system thrust/load trends. Computational fluid dynamics (CFD) results will be compared against available lab-scale experimental data, and reduced-order blade element momentum (BEM) results will be benchmarked against CFD predictions to characterize modeling error at relevant scales.
Overview of requested support:
Pterofin is requesting support to model Skimmer performance using a two-stage approach. First, NLR will run a broad parameter sweep using a reduced-order BEM model that is computationally efficient and well suited for rapidly exploring design and operating space. Because reduced-order assumptions can limit accuracy—particularly when unsteady separation dynamics become important—the sweep is used to identify the most promising (and most informative) cases to evaluate next. Second, selected cases will be simulated using higher-fidelity CFD to more accurately represent device performance, quantify loads, and estimate error in the reduced-order predictions. Where applicable, CFD accuracy will also be assessed through comparisons to prior experimental results.
Rationale for facility selection:
NLR (formerly NREL) brings deep expertise in hydrofoil and turbine-adjacent modeling, including the development and application of open-source engineering tools used broadly across renewable-energy industries. One such tool is OpenFAST, an aero-hydro-servo-elastic modeling framework originally developed for wind energy and increasingly leveraged across related energy-conversion systems. Because the Skimmer’s operation differs from traditional rotating turbines, the rotor aerodynamics/hydrodynamics module (AeroDyn) can be applied in a targeted way to support reduced-order performance estimation and sensitivity studies. NLR also has extensive experience with high-fidelity CFD for hydrofoils and marine energy devices, along with access to high-performance computing resources needed to run and iterate on complex simulations. Together, these capabilities make NLR a strong fit to deliver a credible power curve, efficiency trends, and uncertainty bounds that can guide next-phase prototype validation and commercialization planning.
Pterofin is currently collaborating with the U.S. Department of Energy’s National Laboratory of the Rockies (NLR, formerly NREL) through TEAMER RFTS-15 technical support to quantify and validate the performance of the Pterofin Skimmer. NLR’s team is well underway on a 3D modeling campaign designed to produce decision-grade outputs—most importantly a defensible power curve and clear efficiency trends across realistic flow conditions. This milestone bridges our earlier lab testing with rigorous, physics-based prediction so investors, partners, and future customers can evaluate the technology with confidence.
Background on technology:
The Pterofin Skimmer is a marine energy system designed to harness energy near the water surface using an oscillating hydrofoil. The foil oscillates about a driveshaft in a pendulum-like motion. Near the end of each swing, the foil also pitches about its spanwise axis so the leading edge remains oriented upstream in the relative flow. A counterbalance and control system regulate wing motion, and the powertrain converts oscillatory motion into single-direction rotation to drive a generator. The Skimmer is designed to perform in lower-flow environments and to operate in shallow or constrained deployment settings.
Background on problem being addressed:
Past work on the Skimmer combined experimental prototype testing with low-fidelity modeling. Prototype testing demonstrated the viability of the concept, but it limited the number of configurations and operating conditions that could be explored. Analytical modeling provided early estimates of performance, but it did not capture several important aspects of operation—such as induction effects, unsteady separation, and variable lift behavior—needed to predict output across a broad operating envelope. This project expands capability by simulating device performance across a wide range of parameters at higher levels of fidelity, revealing which configurations increase performance, which reduce loads or improve stability, and which design/control choices should be prioritized for further optimization.
Statement of intended outcomes and what metrics will be used:
The project’s intended outcomes are: (1) identify which geometric and operational parameters improve performance; (2) quantify performance for a defined set of design and operating conditions to support development of a power curve; and (3) estimate uncertainty by comparing mid-fidelity and high-fidelity modeling approaches. The following metrics will be evaluated: driveshaft torque and rotational speed, mechanical power, hydrofoil pitching torque, and overall system thrust/load trends. Computational fluid dynamics (CFD) results will be compared against available lab-scale experimental data, and reduced-order blade element momentum (BEM) results will be benchmarked against CFD predictions to characterize modeling error at relevant scales.
Overview of requested support:
Pterofin is requesting support to model Skimmer performance using a two-stage approach. First, NLR will run a broad parameter sweep using a reduced-order BEM model that is computationally efficient and well suited for rapidly exploring design and operating space. Because reduced-order assumptions can limit accuracy—particularly when unsteady separation dynamics become important—the sweep is used to identify the most promising (and most informative) cases to evaluate next. Second, selected cases will be simulated using higher-fidelity CFD to more accurately represent device performance, quantify loads, and estimate error in the reduced-order predictions. Where applicable, CFD accuracy will also be assessed through comparisons to prior experimental results.
Rationale for facility selection:
NLR (formerly NREL) brings deep expertise in hydrofoil and turbine-adjacent modeling, including the development and application of open-source engineering tools used broadly across renewable-energy industries. One such tool is OpenFAST, an aero-hydro-servo-elastic modeling framework originally developed for wind energy and increasingly leveraged across related energy-conversion systems. Because the Skimmer’s operation differs from traditional rotating turbines, the rotor aerodynamics/hydrodynamics module (AeroDyn) can be applied in a targeted way to support reduced-order performance estimation and sensitivity studies. NLR also has extensive experience with high-fidelity CFD for hydrofoils and marine energy devices, along with access to high-performance computing resources needed to run and iterate on complex simulations. Together, these capabilities make NLR a strong fit to deliver a credible power curve, efficiency trends, and uncertainty bounds that can guide next-phase prototype validation and commercialization planning.
