Gas turbines engine designers are leaning towards aircraft engine architectures due to their footprint, weight, and performance advantages. Such engines need some modifications to both the combustion system, to comply with emission limits, and turbine rotational speed. Aero derivative engines maintain the same legacy aircraft engine architecture, and replace the fan and booster with higher speed compressor booster driven by a single stage intermediate turbine. A multistage free power turbine (FPT) sits on a separate shaft to drive compressors for Liquefied Natural Gas (LNG) applications or generators. The intermediate power turbine (IPT) design is important for the engine performance as it drives the booster compressor and sets the inlet boundary conditions to the downstream power turbine. This paper describes the experience of Baker Hughes, a GE company (BHGE) in the design of the intermediate turbine that sits in between a GE legacy aircraft engine core exhaust and the downstream power turbine. This paper focuses on the flow path of the TCF/intermediate turbine and the associated design, as well as on the 3D steady and unsteady CFD assisted design of the IPT stage to control secondary flows in presence of through flow curvature induced by the upstream TCF.

Additive Manufacturing (AM) in turbine technology enables the manufacture of complex and detailed shapes such as optimized cooling channel designs. However, the AM components are usually produced with high surface roughness. The ability to predict the pressure loss and heat transfer during the AM components’ design phase gives the designer an extra edge to arrive at a better design. In this paper, numerical prediction for the effect of roughness on pressure loss (friction factor) and heat transfer (Nusselt number) for flow in the internal channel is discussed. Numerical simulations were performed using the commercial computational fluid dynamics (CFD) tool by ‘Siemens Star-CCM+’. Initially, the best practices for the CFD process were arrived at by comparing the CFD results with the theoretical correlations for a fully developed channel flow. Further, these best practices were invoked to validate the two test cases from the open literature. From the first test case, three test coupons with the lowest, intermediate, and the highest level of roughness were selected for the validation. From the second test case, in-line and stagger configurations were selected for validation. To reduce the simulation time, modeling the full channel domain as a single channel was explored. The single-channel results were found to be matching well with the full channel results at the two Reynold’s numbers simulated. For all the cases, the friction factor predictions are close to the theoretical and test data, whereas the Nusselt number predictions show a consistent trend with the theoretical data but over-predicts when compared to the test data.

Gas turbines engine designers are leaning toward aircraft engine architectures due to their footprint, weight, and performance advantages. Such engines need some modifications to both the combustion system, to comply with emission limits, and turbine rotational speed. Aeroderivative engines maintain the same legacy aircraft engine architecture and replace the fan and booster with a higher speed compressor booster driven by a single-stage intermediate turbine. A multistage free power turbine (FPT) sits on a separate shaft to drive compressors for liquefied natural gas (LNG) applications or generators. The intermediate-power turbine (IPT) design is important for the engine performance as it drives the booster compressor and sets the inlet boundary conditions to the downstream power turbine. This paper describes the experience of Baker Hughes, a GE company (BHGE) in the design of the intermediate turbine that sits in between a GE legacy aircraft engine core exhaust and the downstream power turbine. This paper focuses on the flow path of the turbine center frame (TCF)/intermediate turbine and the associated design, as well as on the 3D steady and unsteady computational fluid dynamics (CFD)-assisted design of the IPT stage to control secondary flows in presence of through flow curvature induced by the upstream TCF.