REal-GAs effects on Loss mechanisms of ORC turbine flows – REGAL-ORC

Wall-resolved and wall-modelled LES methods for organic vapor flows in turbomachinery will be developed in this project based on a combined numerical-experimental approach employing high-accurate numerical solvers, a new organic vapor wind tunnel test facility and a new generation of hot-film surface sensors.
Two primary test configurations will be investigated, namely, the flow over a flat plate and though a simplified turbine cascade vane. Flow properties, including turbulence quantities, will be measured by means of hot-wire anemometry, conventional and focusing Schlieren systems, Pitot and five-hole-probes, laser-based anemometry, and by a new generation of miniaturized hot-film surface sensors tailored to the very special needs of organic vapor flows.

Thanks to the close collaboration between a theoretical/numerical research group (Paris, France) and an experimental group (Muenster, Germany) and the support by a microsystem technology group (Ilmenau, Germany), the project will enable, for the very first time for organic vapors, several significant advances: 1) characterization of transitional and turbulent flow behavior via simulations and experiments; 2) insight into blade vane loss mechanisms and assessment of the capability of numerical models to capture them; 3) development of innovative high-fidelity CFD tools specifically tailored for ORC turbomachinery; 4) development and release of new thermal surface sensors for measuring flow and turbulence quantities in the very thin wall region for real-gases.

The new experimental and CFD data and the outcomes of the present research will constitute benchmark cases for the scientific community and the interested public.

• Cinnella, P., Matar, C., Gloerfelt, X., Reinker, F. & aus der Wiesche, S., 2022, Investigation
of non-ideal gas flows around a circular cylinder, Energy in second revision.
• Hake, L., Sundermeier, S., Cakievski, L., Bäumer, J., aus der Wiesche, S., Matar, C., Cinnella,
P. & Gloerfelt, X., 2022, Hot-wire anemometry in high subsonic organic vapor flows, Journal
of Turbomachinery, submitted. ASME.
• Cinnella, P., Matar, C., Gloerfelt, X., Reinker, F. & aus der Wiesche, S., 2021, High subsonic
organic vapor flow past a circular cylinder, in 6th International Seminar on ORC Power Systems,
number 84, p. 1–9, Munich, Germany, October 11-13.
• Bienner, A., Gloerfelt, X. & Cinnella, P., 2022, Numerical study of boundary-layer transition in
a high-subsonic organic vapor flow, in 56th 3AF International Conference AERO2022, Toulouse, France,
March 28-30. AAAF.
• Hake, L., Sundermeier, S., Cakievski, L., Bäumer, J., aus der Wiesche, S., Matar, C., Cinnella,
P. & Gloerfelt, X., 2022, Hot-wire anemometry in high subsonic organic vapor flows, in ASME Turbo
Expo 2022 Turbomachinery Technical Conference and Exposition, number GT2022-81686, Rotterdam, The
Netherlands, June 13-17. ASME.
• Bienner, A., Gloerfelt, X., Cinnella, P., Hake, L., aus der Wiesche, S. & Strehle, S., 2022,
Study of bypass transition in dense-gas boundary layers, TSFP12, Osaka, Japan, July 19-22.
• Bienner, A., Gloerfelt, X. & Cinnella, P., 2022, Assessment of a high-order implicit residual smoothing
time scheme for multiblock curvilinear meshes, ICCFD11, Maui, USA, July 11-15.
• Sundermeier, S., C., Matar, aus der Wiesche, S., Cinnella, P., Hake, L. & Gloerfelt, X.,
2022, Experimental and numerical study of transonic flow of an organic vapor past a circular cylinder,
NICFD2022, London, United
Kingdom, November 3-4.
• Hake, L., aus der Wiesche, S., Bienner, A., Cinnella, P. & Gloerfelt, X., 2022, Grid-generated
decaying turbulence in an organic vapour flow, NICFD2022, London, United Kingdom, November 3-4.
• Hake, L., Sundermeier, S., aus der Wiesche, S., Bienner, A., Gloerfelt, X., Matar, C. & Cinnella,
P., 2022, CFD-supported data reduction of hot-wire anamometry signals for compressible organic
vapor flows, in XXVI Biennial Symposium on Measuring Techniques in Turbomachinery (Transonic and
Supersonic Flow in Cascades and Turbomachines), Pisa, Italy, September 28-30.
• Bienner, A., Gloerfelt, X. & Cinnella, P., 2022, Leading-edge effects in freestream turbulence induced
transition in a dense gas flow, in Workshop Direct and Large-Eddy Simulation (DLES13), Udine,
Italy, October 26-29.
• Matar, C., Cinnella, P., Gloerfelt, X., Sundermeier, S., Hake, L. & aus der Wiesche, S., 2022,
Numerical investigation of the transonic non-ideal gas flow around a circular cylinder at high Reynolds
number, in Workshop Direct and Large-Eddy Simulation (DLES13), Udine, Italy, October 26-29.

Organic Rankine Cycle (ORC) power systems offer a great potential for waste heat recovery and environmental-friendly power generation but relatively little is known regarding the impact of real-gas effects on loss mechanisms in ORC turbine expanders. A further increase of ORC turbine efficiencies can only be achieved if relevant non-ideal compressible fluid dynamical phenomena are better understood and modeled. Computational fluid dynamics (CFD) tools currently used in ORC design, based on Reynolds-averaged Navier-Stokes (RANS) models, are affected by many notorious flaws and uncertainties, and large-eddy-simulation (LES) or direct-numerical-simulation (DNS) methods are a promising tool for improving our fundamental understanding of these flows. The application of LES and DNS methods for real-gas flows in turbomachinery configurations is an open challenge, due to the high Reynolds numbers and the complex thermophysical models required and requires high-quality experimental data for their validation that are not available so far.
Wall-resolved and wall-modelled LES methods for organic vapor flows in turbomachinery will be developed in this project based on a combined numerical-experimental approach employing high-accurate numerical solvers, a new organic vapor wind tunnel test facility and a new generation of hot-film surface sensors. The project will explicitly identify and quantify real-gas effects on laminar-to-turbulent transition, flow separation, shock-wave-boundary layer interactions and wake development and, ultimately, their impact on loss mechanisms in the transonic flow regime. Two primary test configurations will be investigated, namely, the flow over a flat plate and though a simplified turbine cascade vane. Flow properties, including turbulence quantities, will be measured by means of hot-wire anemometry, conventional and focusing Schlieren systems, Pitot and five-hole-probes, laser-based anemometry, and by a new generation of miniaturized hot-film surface sensors tailored to the very special needs of organic vapor flows. Thanks to the close collaboration between a theoretical/numerical research group (Paris, France) and an experimental group (Muenster, Germany) and the support by a microsystem technology group (Ilmenau, Germany), the project will enable, for the very first time for organic vapors, several significant advances: 1) characterization of transitional and turbulent flow behavior via simulations and experiments; 2) insight into blade vane loss mechanisms and assessment of the capability of numerical models to capture them; 3) development of innovative high-fidelity CFD tools specifically tailored for ORC turbomachinery; 4) development and release of new thermal surface sensors for measuring flow and turbulence quantities in the very thin wall region for real-gases. The new experimental and CFD data and the outcomes of the present research will constitute benchmark cases for the scientific community and the interested public.