ECE AYLI

My Thesis: 

​

PhDThesis:DESIGN AND PARAMETER OPTIMIZATION OF FRANCIS TYPE TURBINES AND DEVELOPMENT OF SUBSTRUCTURE OF MODEL TESTS BY NUMERICAL METHODS

Abstract: In the first part, CFD based 3D numerical simulations of steady turbulent flow in a Francis turbine for an actual power plant, BUSKI HES in Turkey, is presented. Depending on the variation of the environmental factors, new and modernized hydropower systems can work at operating regions both full and part load conditions. Second part of this thesis presents hill chart prediction and flow characteristics of an entire Francis turbine (BUSKİ HEPP). The interactions between components especially between the stator and rotor are investigated for different head and guide vane openings. Loss analysis is carried out, as well. Designed Francis turbine can work with more than %90 efficiency in a wide range. Best efficiency point (BEP) and design point comparisons are shown as well. To obtain a reliable numerical Hill chart, forty-two full turbine analyses are performed for different head and guide vane openings using computational fluid dynamics (CFD) and the design is finalized accordingly.Most challenging component for the design process of a hydraulic turbine is the runner. There are several parameters which determine the turbine vii performance and cavitation characteristics during the design phase of the runner such as flow beta angle,flow alfa angle, blade beta angle, inlet and outlet diameter of the runner and blade height. In the optimum design of the runner, to ensure the necessary conditons for head, flow rate and power of the system are met, all the parameters must reach to appropriate values. The hydraulic designer, should allocate a long time to optimize the parameters, and should have experience about this iterative process. In the third part, some of the turbine runner parameters that affect turbine performance and cavitation characteristics are investigated in detail. Turbine rotational speed, runner geometry, system head and flow rate effects vary in each custom turbine design specifically made for a specific hydroelectric power plant. To eliminate this situation and to obtain universal results, the effects of design parameter are investigated for four different runners designed for four different hydroelectric power plants. To help the hydraulic designer, general influences of the parameters on the turbine performance are summarized; empirical formulations are derived for runner performance characterization.In the last two part, model turbine dimensions and operating conditions of the KEPEZ 1 HEPP, in Turkey is determined which will be tested at the Center of Hydro Energy Research at TOBB University of Economics and Technology. The model tests will be performed for verification purposes. The overall hydraulic characteristics of the prototype and the model are determined; several analyses are performed to be able to perform the CFD aided design and model tests of the designed turbine. Efficiency values over a wide range of operating conditions are obtained by CFD analyses for both prototype and model turbine by conducting eighty full turbine analyses and numerical hill charts for the prototype and model turbines are constructed. Scale effects between the model and prototype are investigated.

​

MSc Thesis:NUMERICAL ANAYSIS OF SUPERSONIC CAVITY FLOW

In this research, internal carriage of stores which is modeled by supersonic rectangular cavity is studied according to explain turbulent, unsteady and complex flow field in the cavity region. High speed flows over open cavities can produce complex unsteady flow fields that are important practical concern in aerospace applications. Therefore to understand the nature of the supersonic flow over an open cavity numerous numerical and experimental studies are performed.In this study, two and three dimensional simulations are performed. Unsteady, compressible and time dependent Reynolds-Averaged Navier-Stokes (URANS) equations are solved for supersonic cavity flow. The effects of numerical parameters and cavity length to depth ratio effects are investigated. The results of the CFD analyses are compared by using the experimental values which are obtained from the experiment with the same flow parameters, for sound pressure levels (SPL) and pressure coefficient distribution given in literature.Supersonic cavity flow physics and flow nature is analyzed. Two dimensional and three dimensional simulation results are compared with each other and it is stated that three dimensional effects cannot be neglected. High speed flow over the cavity creates complex, unsteady and difficult flow field. In this complex flow field, pressure fluctuations and resonance takes place. Cavity length has an important effect on the cavity flow.

​