Fluid flow modelling through an axial-flow microhydro turbine

U ovom je istraživanju analizirano trodimenzionalno polje fluida aksijalne mikrohidro turbine nazvane Agnew. Sve numeričke simulacije su izvedene pomoću OpenFOAM, računalnog koda dinamike fluida otvorenog izvora (CFD), kako bi se istražila interakcija rotor-stator i gubitci koji nastaju u turbini. Klizna dodirna ravnina korištena je da se poremećaj stacionarne domene prenese na rotacijsku domenu i obratno. Također je ispitano nekoliko modela turbulencije zajedno s funkcijom zida kako bi se uzela u obzir turbulencija u strujanju. Dobiveni rezultati pokazuju da schema advekcije visoke rezolucije, koja kombinira dodirnu ravninu za modeliranje interakcije rotor-stator zajedno s intenzitetom turbulencije I = 6 % na ulazu, najbolje odgovara eksperimentalnim rezultatima.In this study, a three-dimensional fluid field of axial-flow type microhydro named Agnew has been investigated. All numerical simulations were performed using OpenFOAM, an open source computational fluid dynamic (CFD) code, to investigate the rotor-stator interaction and losses occurring in the turbine. A sliding interface plane was used to pass the disturbance of stationary domain to rotary domain and vice versa. Several turbulence models were also examined together with wall function in order to take into account the turbulence in the flow. The obtained results show that a high resolution advection scheme, mixing plane to model the rotor-stator interaction together with a turbulence intensity of I = 6 % at the inlet, best matches with the experimental results

A smart load-speed sensitive cooling map to have a high- performance thermal management system in an internal combustion engine

Considering the fact that electrification is increasingly used in internal combustion engines, this paper aims at presenting a smart speed-load sensitive cooling map for better thermal management. For this purpose, first, thermal boundary conditions for the engine cooling passage were obtained by thermodynamic and combustion simulation. Next, the temperature distribution of the cooling passage walls was determined using conjugate heat transfer method. Then, the effect of engine load on wall temperature distribution was investigated, and it was observed that in the conventional mode where the cooling flow is only affected by the engine speed, the engine is faced with over-cooling and under-cooling. Therefore, the optimum flow for cooling the engine was achieved in such a way that the engine is hot enough and kept free from damage, while the engine has a more uniform temperature distribution. These calculations were performed by considering the boiling phenomenon. The results showed using the cooling map leads to a significant reduction in coolant flow, which in turn reduces the power consumption of the water pump and size of the radiator. Moreover, fuel consumption, hydrocarbon emission production, and the needed power of the coolant pump are enhanced by 2.1, 8.6, and 44.3%, respectively.Irankhodro Powertrain Company (IPCo)http://www.elsevier.com/locate/energy2022-04-22hj2021Mechanical and Aeronautical Engineerin

Sensitivity Analysis of the Artificial Neural Network Outputs in Friction Stir Lap Joining of Aluminum to Brass

Al-Mg and CuZn34 alloys were lap joined using friction stir welding while the aluminum alloy sheet was placed on the CuZn34. In addition, the mechanical properties of each sample were characterized using shear tests. Scanning electron microscopy (SEM) and X-ray diffraction analysis were used to probe chemical compositions. An artificial neural network model was developed to simulate the correlation between the Friction Stir Lap Welding (FSLW) parameters and mechanical properties. Subsequently, a sensitivity analysis was performed to investigate the effect of each input parameter on the output in terms of magnitude and direction. Four methods, namely, the “PaD” method, the “Weights” method, the “Profile” method, and the “backward stepwise” method, which can give the relative contribution and/or the contribution profile of the input factors, were compared. The PaD method, giving the most complete results, was found to be the most useful, followed by the Profile method that gave the contribution profile of the input variables