An Inverse Method of Designing the Cooling Passages of Turbine Blades Based on the Heat Adjoint Equation

A method of solution of the inverse problem in heat conduction is presented. The method, based on an adjoint optimization procedure, is applied to the design of the pattern of cooling passages inside turbine blades. For blade coating technologies, the general case of a non-homogeneous solid material is considered. The numerical solution of both the temperature field and of the adjoint problem is based on a finite element method. The new formulation of the adjoint thermal problem is deduced for three different parametric representation of the internal cooling passages. This allows the designer to select the most adequate blade parametrization, going from blades with circular coolant passages to modern multi-holed hollow blades. The mathematical method, the adjoint problem solution and the enforcement of geometric constraints are explained and the procedure is validated against theoretical, experimental data and numerical solution available in open literature

INVERSE DESIGN OF INTERNALLY COOLED TURBINE BLADES BASED ON THE HEAT ADJOINT EQUATION

A method of solution of the inverse problem in heat conduction is presented. The method, based on an adjoint optimization procedure, is applied to the design of the pattern of circular cooling passages inside coated turbine blades. The general case of a non-homogeneous solid material is considered. The numerical solution of both the temperature field and of the adjoint problem is based on a finite element method. The mathematical method is explained and the procedure is validated against theoretical and experimental data available in open literature

Simultaneous reconstruction of the spatially-distributed reaction coefficient, initial temperature and heat source from temperature measurements at different times

In many practical situations concerned with high temperatures/pressures/loads and/or hostile environments, certain properties of the physical medium, geometry, boundary and/or initial conditions are not known and their direct measurement can be very inaccurate or even inaccessible. In such situations, one can adopt an inverse approach and try to infer the unknowns from some extra accessible measurements of other quantities that may be available. However, the simultaneous identification of several non-constant physical properties along with initial and/or boundary conditions is very challenging, especially when it cannot be decoupled, as it combines both nonlinear as well as ill-posedness features. One such new inverse problem concerning the identification of the space-dependent reaction coefficient, the initial temperature and the source term from measured temperatures at two instants t1, t2 and at the final time T , where 0 < t1 < t2 < T , is investigated in this paper. Insight into the uniqueness of solution is gained by considering various particular cases. Moreover, as in practice the input temperature data are usually noise polluted due to the errors that are inherently present, their influence on the solution of inversion has to be assessed. As such, the least-squares objective functional modelling the gap between the measured and computed data is minimized to obtain the quasi-solution to the inverse problem, and the Fréchet gradients are obtained. The conjugate gradient method (CGM) with the Fletcher–Reeves formula is applied to estimate the three unknown coefficients numerically. Numerical examples are illustrated to show that accurate and stable numerical solutions are obtained using the CGM regularized by the discrepancy principle

Standards in semen examination: publishing reproducible and reliable data based on high-quality methodology

Biomedical science is rapidly developing in terms of more transparency, openness and reproducibility of scientific publications. This is even more important for all studies that are based on results from basic semen examination. Recently two concordant documents have been published: the 6th edition of the WHO Laboratory Manual for the Examination and Processing of Human Semen, and the International Standard ISO 23162:2021. With these tools, we propose that authors should be instructed to follow these laboratory methods in order to publish studies in peer-reviewed journals, preferable by using a checklist as suggested in an Appendix to this article