The scope of this work was to develop a technique based on the regression method and apply it on a real cooled geometry for measuring its internal heat transfer distribution. The proposed methodology is based upon an already available literature approach. For implementation of the methodology, the geometry is initially heated to a known steady temperature, followed by thermal transient, induced by injection of ambient air to its internal cooling system. During the thermal transient, external surface temperature of the geometry is recorded with the help of infrared camera. Then, a numerical procedure based upon a series of transient finite element analyses of the geometry is applied by using the obtained experimental data. The total test duration is divided into time steps, during which the heat flux on the internal surface is iteratively updated to target the measured external surface temperature. The final procured heat flux and internal surface temperature data of each time step is used to find the convective heat transfer coefficient via linear regression. This methodology is successfully implemented on three geometries: a circular duct, a blade with U-bend internal channel, and a cooled high pressure vane of real engine, with the help of a test rig developed at the University of Florence, Italy. The results are compared with the ones retrieved with similar approach available in the open literature, and the pros and cons of both methodologies are discussed in detail for each geometry.

The current article focuses on the investigation of entropy generation effects in mixed convective magnetohydrodynamic nanofluid flow past a stretching surface. The effects of viscous and joule dissipation are also incorporated in the present problem. By utilizing suitable similarity variables, the equations that govern the transport phenomena are transformed into nonlinear ordinary differential equations. These converted equations are then solved numerically through fourth fifth order Runge-Kutta-Fehlberg method with shooting procedure. The obtained results are compared with the previously existing studies under certain limiting cases. A thermodynamical analysis of the problem has been carried out and the effects of variation in physical parameters on flow, heat transfer and nanoparticle concentration are discussed by using tables and graphs. Moreover, the influence of these parameters on entropy production is examined by plotting graphs of local entropy generation number and averaged entropy generation number. A detail comprehensive analysis of the problem has been done and the results are interpreted qualitatively.

The aim of this work is to present the development and application of a measurement technique that allows to record internal heat transfer features of real components. In order to apply this method, based on similar approaches proposed in previous literature works, the component is initially heated up to a steady temperature, then a thermal transient is induced by injecting cool air in the internal cooling system. During this process, the external temperature evolution is recorded by means of an infrared (IR) camera. Experimental data are then exploited to run a numerical procedure, based on a series of transient finite element analyses of the component. In particular, the test duration is divided into an appropriate number of steps and, for each of them, the heat flux on internal surfaces is iteratively updated as to target the measured external temperature distribution. Heat flux and internal temperature data for all the time steps are eventually employed in order to evaluate the convective heat transfer coefficient via linear regression. This technique has been successfully tested on a cooled high-pressure vane of a Baker Hughes heavy-duty gas turbine, which was realized thanks to the development of a dedicated test rig at the University of Florence, Italy. The obtained results provide sufficiently detailed heat transfer distributions in addition to allowing to appreciate the effect of different coolant mass flow rates. The methodology is also capable of identifying defects, which is demonstrated by inducing controlled faults in the component.

The present article aims to investigate the entropy impacts on boundary layer flow and heat transmission of a hydromagnetic viscous fluid past a contracting sheet. Similarity transmutations are utilized to transform the momentum and energy equations into ordinary differential equations. The expressions of velocity (V) and temperature (T) for different parameters are obtained to compute local entropy generation number (N_s) and Bejan number (Be). A profound study is performed to attain the exact solution for relevant parameters, and the outcomes are elucidated graphically. The solution is presented in the form of an incomplete Gamma function. Heat transfer entropy effects are dominant at contracting sheet surface while entropy effects due to fluid friction and magnetic field are significant in boundary layer region. The outcomes of current study illustrate that the optimal design and the efficient performance of a thermally designed system can be improved by selecting the appropriate values of the flow parameters. It will enable scientists and engineers to minimize the impacts of entropy generation and to construct an efficient and productive thermodynamical system.

The present paper examines the entropy effects in flow and heat transfer of viscous fluid in a porous medium between two infinite radially stretching surfaces. With the aid of suitable similarity transformations, the partial differential equations describing the flow and heat transfer phenomenon are converted into nonlinear ordinary differential equations. Analytical and numerical solutions of these equations are obtained using homotopy analysis method and shooting technique with Runge Kutta Fehlberg method. The effects of various dimensionless parameters such as permeability parameter K, Reynolds number Re, Prandtl number Pr and Brinkman number Br on flow and heat transfer characteristics as well as on entropy generation are discussed in detail through graphs and tables.