One serious challenge of energy systems design, wind turbines in particular, is the need to match the system operation to the variable load. This is so because system efficiency drops at off-design load. One strategy to address this challenge for wind turbine blades and obtain a more consistent efficiency over a wide load range, is varying the blade geometry. Predictable morphing of wind turbine blade in reaction to wind load conditions has been introduced recently. The concept, derived from fish locomotion, also has similarities to spoilers and ailerons, known to reduce flow separation and improve performance using passive changes in blade geometry. In this work, we employ a fully coupled technique on CFD and FEM models to introduce continuous morphing to desired and predetermined blade design geometry, the NACA 4412 profile, which is commonly used in wind turbine applications. Then, we assess the aerodynamic behavior of a morphing wind turbine airfoil using a two-dimensional computation. The work is focused on assessing aerodynamic forces based on trailing edge deflection, wind speed, and material elasticity, that is, Young's modulus. The computational results suggest that the morphing blade has superior part-load efficiency over the rigid NACA blade. Copyright © 2013 John Wiley & Sons, Ltd.

Two-dimensional CFD modeling of the heat and mass transfer process during sewage sludge drying in a solar dryer: The paper presents key assumptions of the mathematical model which describes heat and mass transfer phenomena in a solar sewage drying process, as well as techniques used for solving this model with the Fluent computational fluid dynamics (CFD) software. Special attention was paid to implementation of boundary conditions on the sludge surface, which is a physical boundary between the gaseous phase - air, and solid phase - dried matter. Those conditions allow to model heat and mass transfer between the media during first and second drying stages. Selection of the computational geometry is also discussed - it is a fragment of the entire drying facility. Selected modelling results are presented in the final part of the paper.

Mathematical modelling of the drying process enables predicting results of adopted process parameters, providing information on the course of drying in different conditions. Obtained information may be used as a basis for optimisation of the design and operating regime of such a system. The paper presents essential assumptions of the created mathematical model of a solar sewage sludge drying system and its implementation in Ansys Fluent environment. Special attention was paid to the solutions of equation of mass and heat transfer in the dried matter – the sewage sludge. The proposed solution uses additionally defined scalar parameters, i.e. sludge temperature and moisture content. The paper also presents a method for taking into account cyclic sludge shuffling. Operation of the shuffling device mechanically interferes with the layer of dried sludge and thus considerably disturbs heat and mass transfer processes in the material. Developed model was subsequently used for analysing influence of selected design and operating parameters on efficiency of the facility. The paper gives exemplary results of simulations aimed at determining impact of shuffling frequency and elevation of air blower on the drying facility's efficiency