COUPLED SIMULATION OF THE SECONDARY AIR FLOW, HEAT TRANSFER, AND STRUCTURAL DEFLECTION OF A GAS TURBINE ENGINE

In secondary air flow in gas turbines, labyrinth seals are used to control the flow to and from each cavity and to the rotor blades for cooling purposes. Those components and the final flow rate are very sensitive to gap clearance and displacement due to structural and thermal loads during operation, therefore designing those seals and knowing the resultant flow rates in each part of the circuit during the design phase is not an easy task, and tuning those gap values may bring significant increase in turbine efficiency. This paper describes the application of coupled commercial codes for secondary air flow and structural simulation for better evaluating temperature profiles and labyrinth seal behavior during operation. Flowmaster V7 was used for building a one dimensional model of the complete secondary air flow path including swirl effects and heat transfer phenomena, and ANSYS was used for building a structural model, taking into account both rotational and thermal loads. The labyrinth seals clearances, and thermal interactions between solid and fluid were coupled bi-directionally between the two simulation software. This simulation focused in the system, including the effects of each region, passage, seal and cavity in the calculations. The turbine model simulated was a VSE's gas turbine under development, having a nominal rotation of 22600 rpm. This paper presents the numerical characteristics of each model, the details about the ID fluid and 3D structural coupling, and the results obtained.