Swirling main flow effects on film cooling: Time resolved adiabatic effectiveness measurements in a gas turbine combustor model. (January 2023)

• Record Type: Journal Article
• Authors: Lenzi, T.; Picchi, A.; Becchi, R.; Andreini, A.; Facchini, B.
• Is Part Of: International journal of heat and mass transfer. Volume 200(2023)
• Publication Date: 2023-01
• Subjects: Effusion cooling -- Combustor cooling -- Pressure sensitive paint -- PSP -- Adiabatic effectiveness; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2022.123554
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: The effectiveness of effusion system for liner is influenced by the swirling flows generated by the swirler injectors A non-reactive single-sector linear combustor has been designed to investigate the impact of Swirl number. Film effectiveness was acquired using fast response pressure sensitive paint (FPSP) technique at 1kHz The time-resolved analysis allowed to track the impact of swirling flow on the effusion cooling system Abstract: Lean burn swirl stabilized combustors represent the key technology to reduce NOx emissions in modern aircraft engines. The high amount of air admitted directly trough the injection system and the higher levels of pressure and temperature requested by the engine cycle make the design of even more efficient cooling systems and the correct estimation of combustor liners heat load a crucial task for the combustor durability. One of the technologies used for the cooling of these components is the effusion cooling, which promotes the formation of a cold layer to protect the liner walls, whose cooling capabilities are described with the adiabatic effectiveness parameter. The effectiveness of these systems is severely influenced by the swirling flows generated by the swirler injectors which promote the mixing between cold and the hot gases of the combustion process. The development of the swirling flow structures inside the combustor chamber and the grade of interaction between swirling flow and the liner walls can be described by the swirl number ( S N ). In order to investigate the impact of the effects of the S N parameter on the adiabatic film effectiveness, a dedicated non-reactive single-sector linear combustor test rig was designed and equipped with three different axial injectors ( S N = 0.6 − 0.8 − 1.0 ) and a cylindrical holes effusion plate to simulate the liner cooling system. Film effectiveness was acquired using Fast response Pressure Sensitive Paint (FPSP) technique; the scale of the model and the acquisition frequency of 1 kHz allowed to track the effusion jets and main flow interactions. The collected results show the importance of using an unsteady analysis to perform an in-depth characterization of the mixing phenomena between the main flow and the coolant which are significantly affected by the swilring characteristics.