Abstract
As the world’s demand for energy continues to grow, gas turbines are looked at as one of main options for power generation. Among the aero derivative and heavy-duty designs, designers are leaning towards aero derivative architecture due to advantage it offers in terms of performance, footprint, and weight. Gas turbine engineers identify “exhaust casing” as the casing which forms the hot gas path after the last stage of the turbine, to recover back pressure and thereby contributing the increased performance of the turbine. In the same way, in aero derivative engines this casing is called as “Turbine Rear Frame (TRF)”. By virtue of aero derivative design philosophy, TRF is exposed to hot gases on one side and colder ventilation air on other side, posing a challenge to designer in terms of thermo-mechanical design aspects. TRF also functions as a load bearing member by transferring loads from all other casings to foundation, using its support legs. The hollow struts of TRF forms a passage for all bearing piping and few secondary flows. All these piping and colder secondary flows have influence on the design of TRF. This paper presents a comparative study of how various configurations of TRF evolved under Baker Hughes Aero derivative portfolio, which concentrates on secondary flow circuit and thermal design aspects, and its impact on component design. This also covers improved aspects in thermal modeling to match the test data measurements. The impact of different thermal behavior on the component with respect to stress, deformation and stiffness are studied. It also captures the effect of secondary flow circuit modifications on the component interfaces. The aspect of design iterations considering the Ultimate load comparing various versions will also be highlighted.
