@article{RueckertIbrarAhmedetal.2024, author = {R{\"u}ckert, Frank Ulrich and Ibrar, Burhan and Ahmed, Arslan and Allweyer, Benjamin and H{\"u}bner, Dirk and Klinger, Friedrich and Knaus, Hermann and Benim, Ali Cemal}, title = {Fluid flow and heat transfer of a novel passive cooling system for gearless wind turbines with a power range of 3-12 MW}, series = {Energy}, volume = {312}, journal = {Energy}, publisher = {Elsevier}, issn = {0360-5442}, doi = {10.1016/j.energy.2024.133478}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-46594}, year = {2024}, abstract = {Today, the gearless horizontal axis wind turbines are mainstream in wind energy industry. High demands of electric power led to bigger systems and active cooling reduces the overall efficiency of the turbines. Passive cooling systems have been examined for the first time for a gearless wind energy generator with power range of 3-12 MW. With further developed heat conductors, it is possible to operate a wind generator in a larger power class with passive cooling components. This is accompanied by enormous cost savings due to elimination of costs for active cooling elements such as the use of fans, pumps, and heat exchangers. An additional factor is the significant reduction in necessary maintenance due to the minimized incidence of corrosion and wear. Design of the cooling fins and an ideal position of the generator within the housing of the wind turbine has been objectives. Mandatory is that maximum temperatures of the generator fins should stay under 155 °C, which could be reached with several designs for different heat exchanger geometries.}, subject = {Windturbine}, language = {en} } @article{MandalBiswasMannaetal.2024, author = {Mandal, Dipak Kumar and Biswas, Nirmalendu and Manna, Nirmal K and Benim, Ali Cemal}, title = {Impact of chimney divergence and sloped absorber on energy efficacy of a solar chimney power plant (SCPP)}, series = {Ain Shams Engineering Journal}, journal = {Ain Shams Engineering Journal}, publisher = {Elsevier}, issn = {2090-4495}, doi = {10.1016/j.asej.2023.102390}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-42410}, year = {2024}, abstract = {A numerical study is carried out meticulously to scrutinize the impact of different shapes of chimneys like circular (outer dia, dc), convergent (outer dia, 0.5dc), divergent (outer dia, 1.5dc), sudden contraction (outer dia, 0.5dc), and sudden expansion (outer dia, 1.5dc) on the performance of an SCPP. Furthermore, the parametric impact with different chimney divergence angles (CDA, ϕ), and ground absorber slope angle (GSA, γ) on the SCPP performance is also scrutinized. Optimum divergence angle (ϕ=+0.75◦) enhances the power generation up to ~ 47\% (76 kW) with a horizontal ground absorber surface. An increase or decrease in CDA lessens the power generation. With a sloped ground absorber angle γ=0.6◦, the gain in power generation is 60\% (82 kW). The study of combination of ground sloped absorber (γ=0.6◦) and divergent chimney (ϕ=+0.75◦) shows enhancement of the power generation upto 80\% (92 kW) more than the classical Manzaranes plant.}, language = {en} } @article{BenimZinser1985, author = {Benim, Ali Cemal and Zinser, Walter}, title = {Investigation into the finite element analysis of confined turbulent flows using a κ-ε model of turbulence}, series = {Computer Methods in Applied Mechanics and Engineering}, volume = {51}, journal = {Computer Methods in Applied Mechanics and Engineering}, number = {1-3}, publisher = {Elsevier}, issn = {0045-7825}, doi = {10.1016/0045-7825(85)90045-3}, pages = {507 -- 523}, year = {1985}, subject = {Finite-Elemente-Methode}, language = {en} } @article{BenimZinser1986, author = {Benim, Ali Cemal and Zinser, Walter}, title = {A segregated formulation of Navier-Stokes equations with finite elements}, series = {Computer Methods in Applied Mechanics and Engineering}, volume = {57}, journal = {Computer Methods in Applied Mechanics and Engineering}, number = {2}, publisher = {Elsevier}, issn = {0045-7825}, doi = {10.1016/0045-7825(86)90015-0}, pages = {223 -- 237}, year = {1986}, subject = {Navier-Stokes-Gleichung}, language = {en} } @article{Benim1988, author = {Benim, Ali Cemal}, title = {A finite element solution of radiative heat transfer in participating media utilizing the moment method}, series = {Computer Methods in Applied Mechanics and Engineering}, volume = {67}, journal = {Computer Methods in Applied Mechanics and Engineering}, number = {1}, publisher = {Elsevier}, issn = {0045-7825}, doi = {10.1016/0045-7825(88)90065-5}, pages = {1 -- 14}, year = {1988}, subject = {Finite-Elemente-Methode}, language = {en} } @article{Benim1989, author = {Benim, Ali Cemal}, title = {Finite element solution of an enclosed turbulent diffusion flame}, series = {International Journal for Numerical Methods in Fluids}, volume = {9}, journal = {International Journal for Numerical Methods in Fluids}, number = {3}, publisher = {Wiley}, issn = {0271-2091}, doi = {10.1002/fld.1650090305}, pages = {289 -- 303}, year = {1989}, abstract = {A finite element formulation of enclosed turbulent diffusion flames is presented. A primitive variables approach is preferred in the analysis. A mixed interpolation is employed for the velocity and pressure. In the solution of the Navier-Stokes equations, a segregated formulation is adopted, where the pressure discretization equation is obtained directly from the discretized continuity equation, considering the velocity-pressure relationships in the discretized momentum equations. The state of turbulence is defined by a κ-ϵ model. Near solid boundaries, a wall function approach is employed. The combustion rates are estimated using the eddy dissipation concept. The expensive direct treatment of the integrodifferential equations of radiation is avoided by employing the moment method, which allows the derivation of an approximate local field equation for the radiation intensity. The proposed finite element model is verified by investigating a technical turbulent diffusion flame of semi-industrial size, and comparing the results with experiments and finite difference predictions.}, subject = {Finite-Elemente-Methode}, language = {en} } @article{BenimZinserSchnell1989, author = {Benim, Ali Cemal and Zinser, Walter and Schnell, Uwe}, title = {Investigation into the finite element analysis of enclosed turbulent diffusion flames}, series = {Applied Mathematical Modelling}, volume = {13}, journal = {Applied Mathematical Modelling}, number = {5}, publisher = {Elsevier}, issn = {0307-904X}, doi = {10.1016/0307-904X(89)90069-3}, pages = {258 -- 267}, year = {1989}, subject = {Finite-Elemente-Methode}, language = {en} } @article{SuhBenim1989, author = {Suh, S.-H. and Benim, Ali Cemal}, title = {The primitive variables formulation of the Navier-Stokes equations using the finite analytic method}, series = {Applied Mathematical Modelling}, volume = {13}, journal = {Applied Mathematical Modelling}, number = {9}, publisher = {Elsevier}, issn = {0307-904X}, doi = {10.1016/0307-904X(89)90066-8}, pages = {550 -- 554}, year = {1989}, subject = {Navier-Stokes-Gleichung}, language = {en} } @article{Benim1990, author = {Benim, Ali Cemal}, title = {Finite element analysis of confined turbulent swirling flows}, series = {International Journal for Numerical Methods in Fluids}, volume = {11}, journal = {International Journal for Numerical Methods in Fluids}, number = {6}, publisher = {Wiley}, issn = {0271-2091}, doi = {10.1002/fld.1650110602}, pages = {697 -- 717}, year = {1990}, abstract = {The finite element method is applied to incompressible and statistically steady confined turbulent swirling flows. A velocity-pressure formulation is employed. The momentum and continuity equations are solved using a segregated algorithm. Two turbulence models, namely the standard κ-ε model and the algebraic stress model, are considered. It is shown that the algebraic stress model leads to significantly more accurate results in swirling flows compared to the κ-ε model. A novel way of implementing the algebraic stress model is presented in which the stresses are coupled to the Navier-Stokes equations in such a way that they 'correct' the effective viscosity hypothesis. This formulation seems to provide a convenient approach for finite elements. In deriving the discretization equations, a streamline-upwind/Petrov-Galerkin method is employed. Comparisons performed between various upwind schemes show that the numerical solution may be substantially affected by the particular upwind procedure used. The analysis is extended to the prediction of particle motion in turbulent swirling flow fields. Here the fluid turbulence is modelled adopting a stochastic approach. The influence of turbulence modelling on particle movement is investigated.}, subject = {Finite-Elemente-Methode}, language = {en} } @article{BenimNeuhoff1993, author = {Benim, Ali Cemal and Neuhoff, H. G.}, title = {Analysis of erosion behaviour in a turbocharger radial turbine}, series = {International Journal for Numerical Methods in Fluids}, volume = {16}, journal = {International Journal for Numerical Methods in Fluids}, number = {4}, publisher = {Wiley}, issn = {0271-2091}, doi = {10.1002/fld.1650160402}, pages = {259 -- 285}, year = {1993}, abstract = {An analysis of the erosion behaviour of a turbocharger radial turbine is presented. The solution domain includes both sides of the radial turbine scroll with double intake and the rotor channel. In the analysis a dilute gas-particle flow assumption is employed. The gas turbulence is defined by the k-ε model. In solving the gas phase equation, the computer code Harwell-FLOW3D is employed, which is based on a finite volume formulation using non-orthogonal body-fitted structured gridding and a pressure correction method. The particle phase is described by a Lagrangian approach, while particle paths are computed deterministically, neglecting the turbulent dispersion. For the computation of particle trajectories the code PTRACK is employed, which has been developed at ABB. Computations are carried out for several particle size classes. The results show that particles are thrown back into the scroll by the rotor at high rates. This seems to be the main source of erosion effects in the scroll. It has been observed that particles are unequally distributed between the scroll sides on their re-entry, resulting in greater erosion on one of the scroll sides. The maximum erosion along the scroll is found to be likely to occur near the scroll end.}, subject = {Erosion}, language = {en} } @article{XiaSmithBenimetal.1997, author = {Xia, Jiliang and Smith, Brian L. and Benim, Ali Cemal and Schmidli, Jiirg and Yadigaroglu, George}, title = {Effect of inlet and outlet boundary conditions on swirling flows}, series = {Computers \& Fluids}, volume = {26}, journal = {Computers \& Fluids}, number = {8}, publisher = {Elsevier}, issn = {0045-7930}, doi = {10.1016/S0045-7930(97)00026-1}, pages = {811 -- 823}, year = {1997}, subject = {Numerische Str{\"o}mungssimulation}, language = {en} }