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This is the final version. Available on open access from Elsevier via the DOI in this record ; The formation and evaporation of nanodroplets in steam ejectors is neglected in many numerical simulations. We analyse the influence of a primary nozzle on steam ejector performances considering phase change processes. The numerical model is validated in detail against experimental data of supersonic nozzles and steam ejectors available in the literature. The results show that the first nonequilibrium condensation is observed within the primary nozzle, while under-expanded supersonic flow causes a second nucleation-condensation process to achieve a large liquid fraction of 0.26 in the steam ejector. The compression process of the supersonic flow results in a steep decrease of the degree of subcooling leading to droplet evaporations. The condensation and evaporation processes repeat alternatively depending on the flow behaviour in the mixing section. The increasing area ratio leads to the transition of the flow structure from under-expanded flows to over-expanded flows in the mixing section. The droplet diameter is about 7 nm in the constant section and the entrainment ratio can reach approximately 0.75 for an area ratio of 8, which achieves a good performance of the steam ejector. ; European Union Horizon 2020 ; Independent Research Fund Denmark ; Innovation Fund of Denmark ; MAN Energy Solutions ; National Natural Science Foundation of China

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record ; Data availability: Data will be made available on request. ; This research develops the non-equilibrium condensation model with sliding mesh technology to solve the unsteady condensing flow inside a 3D wet steam stage of steam turbine with transient rotor-stator interaction. The maximum fluctuation of time-dependent condensation parameters is predicted. The condensation loss and entropy generation considering the off-design operation and rough blades are also evaluated quantitatively. The results showed that the secondary expansion and condensation occur near the rotor trailing edge. At design operation, the time-dependent subcooling fluctuates from −9.81 K to 8.06 K at the maximum fluctuation location. The frozen rotor method over-predicts the expansion and condensation characteristics in the steam turbine stage. Moreover, the maximum relative fluctuation of time-dependent wetness is 37.14% when it changes from 0.022 to 0.048. At off-design operation, the p-T diagram is applied to compare the expansion and condensation processes. The inlet subcooling increases by 40 K, resulting in an increase of 110.34% in outlet wetness. The phase of condensation loss with high off-design inlet subcooling is ahead of that with low off-design inlet subcooling. The fluctuation of time-dependent condensation loss with off-design inlet subcooling is about 102.28 kW. In addition, the back pressure ratio changes from 0.55 to 0.10, resulting in an increase of 190.91% in outlet wetness. The fluctuation of time-dependent condensation loss with off-design back pressure ratio can reach 112.3 kW. Besides, the maximum time-averaged entropy generation and exergy destruction due to the increase of surface roughness can reach 9.37 kJ kg−1 K−1 and 5.71 kW. ; National Natural Science Foundation of China ; European Union Horizon 2020

7 pags., 4 figs., 3 pags. ; The Dzyaloshinskii-Moriya interaction (DMI) is an antisymmetric exchange interaction that stabilizes chiral spin textures. It is induced by inversion symmetry breaking in noncentrosymmetric lattices or at interfaces. Recently, interfacial DMI has been found in magnetic layers adjacent to transition metals due to the spin-orbit coupling and at interfaces with graphene due to the Rashba effect. We report direct observation of strong DMI induced by chemisorption of oxygen on a ferromagnetic layer at room temperature. The sign of this DMI and its unexpectedly large magnitude—despite the low atomic number of oxygen—are derived by examining the oxygen coverage–dependent evolution of magnetic chirality. We find that DMI at the oxygen/ ferromagnet interface is comparable to those at ferromagnet/transition metal interfaces; it has enabled direct tailoring of skyrmion's winding number at room temperature via oxygen chemisorption. This result extends the understanding of the DMI, opening up opportunities for the chemisorption-related design of spin-orbitronic devices. ; This work has been supported by the NSF (DMR-1610060 and DMR-1905468) and the UC Office of the President Multicampus Research Programs and Initiatives (MRP-17- 454963). Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under contract no. DE-AC02- 05CH11231. Work at GU has been supported, in part, by SMART (2018-NE-2861), one of seven centers of nCORE, a Semiconductor Research Corporation program, sponsored by the National Institute of Standards and Technology (NIST). A.M. and M.A.G.B. acknowledge support from MINECO (Spain) under the project no. MAT2017-87072-C4-2-P and from Comunidad de Madrid under the project no. S2018/NMT4321. The Jülich team acknowledges financial support from the DARPA TEE program through grant MIPR (# HR0011831554) from the DOI, the European Union H2020-INFRAEDI-2018-1 program (grant no. 824143, project "MaX— Materials at the exascale"), the Deutsche Forschungsgemeinschaft (DFG) through SPP 2137 "Skyrmionics" (project BL 444/16), the Collaborative Research Centers SFB 1238 (project C01), and computing resources at the supercomputers JURECA at Juelich Supercomputing Centre and JARA-HPC from RWTH Aachen University (projects jias1f and jara0197). R.L.C., A.K.S., and R.W. acknowledge financial support from the European Union via an International Marie Curie Fellowship (grant no. 748006). H.D. acknowledges the support of the National Key R&D Program of China (grant no. 2017YFA0303202) and the National Natural Science Foundation of China (grant nos. 11734006 and 51571109). E.G.M. acknowledges support from MINECO (Spain) under grants MAT2014-52477 and FIS2017-82415-R and from MECD (Spain) under grant PRX17/00557