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A computational study on the effects of active flow control to the evolution of the wingtip vortices of a three dimensional wing
Skarolek, Vilém ; Hradil, Jiří (oponent) ; Karampelas, Stavros (vedoucí práce)
In the present thesis, series of RANS calculations of the flow past a NACA 0015 wing at different angles of attack with active flow control have been performed. Active flow control configurations are applied on the wing's surface at a Mach number of M=0.21 and Re= 2500000. Several types and placements are examined in order to find the most powerful control configuration and energy efficient. The proposed concept in this study does not follow the conventional active control methods past wings. Large blowing surfaces and low velocity magnitudes at the slot's exits are considered and the energy efficiency is examined for a number of variants. Strategies for drag reduction and lift increase of the wing are demonstrated thoroughly by varying some of the actuation parameters. The active control when operating under some specific conditions could reach very high energy efficiency ratios at all angles of attack, while in the same time could be able to reduce significantly the total drag of the wing, increase the total lift or combine effectively those favorable effects for better flight performance. Maximum drag decrease could exceed 40% of the total drag at low angles of attack, with still positive energy income.
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Parametric study of casing treatment for turbine blade in aero engine application
Kníř, Jakub ; Popela, Robert (oponent) ; Karampelas, Stavros (vedoucí práce)
This present thesis addresses the question whether it is possible to obtain compressor’s performance increase with the aid of flow numerical simulations. The main objective is to extend the stable operating range of an axial single stage compressor by using passive flow control devices located on the compressor shroud. Firstly, it is examined the rotor’s tip leakage flow and after that, the overall performance without control. When reducing the mass flow rate, the simulation reveals an increased influence of tip vortex on the main flow. Additionally, large tip vortex is observed close to stall condition. Therefore, four different casing treatments are designed by implementing sinusoidal reshaping to control the tip vortex. Three out off four tested configurations showed ability to extend significantly the stall margin region. However, an increase in the operability had a penalty for the efficiency. On the end of the presented work recommendations are proposed for future research.
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Parametric study of casing treatment for turbine blade in aero engine application
Kníř, Jakub ; Popela, Robert (oponent) ; Karampelas, Stavros (vedoucí práce)
This present thesis addresses the question whether it is possible to obtain compressor’s performance increase with the aid of flow numerical simulations. The main objective is to extend the stable operating range of an axial single stage compressor by using passive flow control devices located on the compressor shroud. Firstly, it is examined the rotor’s tip leakage flow and after that, the overall performance without control. When reducing the mass flow rate, the simulation reveals an increased influence of tip vortex on the main flow. Additionally, large tip vortex is observed close to stall condition. Therefore, four different casing treatments are designed by implementing sinusoidal reshaping to control the tip vortex. Three out off four tested configurations showed ability to extend significantly the stall margin region. However, an increase in the operability had a penalty for the efficiency. On the end of the presented work recommendations are proposed for future research.
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A computational study on the effects of active flow control to the evolution of the wingtip vortices of a three dimensional wing
Skarolek, Vilém ; Hradil, Jiří (oponent) ; Karampelas, Stavros (vedoucí práce)
In the present thesis, series of RANS calculations of the flow past a NACA 0015 wing at different angles of attack with active flow control have been performed. Active flow control configurations are applied on the wing's surface at a Mach number of M=0.21 and Re= 2500000. Several types and placements are examined in order to find the most powerful control configuration and energy efficient. The proposed concept in this study does not follow the conventional active control methods past wings. Large blowing surfaces and low velocity magnitudes at the slot's exits are considered and the energy efficiency is examined for a number of variants. Strategies for drag reduction and lift increase of the wing are demonstrated thoroughly by varying some of the actuation parameters. The active control when operating under some specific conditions could reach very high energy efficiency ratios at all angles of attack, while in the same time could be able to reduce significantly the total drag of the wing, increase the total lift or combine effectively those favorable effects for better flight performance. Maximum drag decrease could exceed 40% of the total drag at low angles of attack, with still positive energy income.
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