Sumiu Uchida

A COMPARISON OF SINGLE AND DOUBLE LIP RIM SEAL GEOMETRIES

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Integrated Combustor and Vane Concept in Gas Turbines

This paper numerically investigates the interaction between multiple can combustors and the first vane in an industrial gas turbine with 16 can combustors and 32 vanes in order to find ways of reducing the overall cooling requirements. Two promising concepts for the overall cooling reduction are presented. In the first, by minimising the axial distance between the combustor wall and the vane, the stagnation region at the LE of every second vane can be effectively shielded from the hot mainstream gases. The LE shielding allows continuous cooling slots to be used (as an alternative to discrete cooling holes) to cool downstream parts of the vane using a portion of the saved LE showerhead cooling air. The second concept proposes a full combustor and first vane integration. In this novel concept the number of vanes is halved and the combustor walls are used to assist the flow turning. All remaining vanes are fully integrated into the combustor walls. In this way the total wetted area of the integrated system is reduced, and by shielding the LEs of the remaining vanes the total amount of cooling air can be reduced. The proposed combustor and first vane integration does not detrimentally affect the aerodynamics of the combustor and vane system. The concept also simplifies the design and should lower the manufacturing costs.Copyright

A New Experimental Facility to Investigate Combustor–Turbine Interactions in Gas Turbines With Multiple Can Combustors

This paper describes a new modular experimental facility that was purpose-built to investigate flow interactions between the combustor and first stage nozzle guide vanes (NGVs) of heavy duty power generation gas turbines with multiple can combustors. The first stage turbine NGV is subjected to the highest thermal loads of all turbine components and therefore consumes a proportionally large amount of cooling air that contributes detrimentally to the stage and cycle efficiency. It has become necessary to devise novel cooling concepts that can substantially reduce the coolant air requirement but still allow the turbine to maintain its aerothermal performance. The present work aims to aid this objective by the design and commissioning of a high-speed linear cascade, which consists of two can combustor transition ducts and four first stage NGVs. This is a modular nonreactive air test platform with engine realistic geometries (gas path and near gas path), cooling system, and boundary conditions (inlet swirl, turbulence level, and boundary layer). The paper presents the various design aspects of the high pressure (HP) blow down type facility, and the initial results from a wide range of aerodynamic and heat transfer measurements under highly engine realistic conditions.

A New Experimental Facility to Investigate Combustor-Turbine Interactions in Gas Turbines With Multiple Can Combustors

A New Experimental Facility to Investigate Combustor-Turbine Interactions in Gas Turbines With Multiple Can Combustors

Leading Edge Shielding Concept in Gas Turbines With Can Combustors

The remarkable developments in gas turbine materials and cooling technologies have allowed a steady increase in combustor outlet temperature and, hence, in gas turbine efficiency over the last half century. However, the efficiency benefits of higher gas temperature, even at the current levels, are significantly offset by the increased losses associated with the required cooling. Additionally, the advancements in gas turbine cooling technology have introduced considerable complexities into turbine design and manufacture. Therefore, a reduction in coolant requirements for the current gas temperature levels is one possible way for gas turbine designers to achieve even higher efficiency levels. The leading edges of the first turbine vane row are exposed to high heat loads. The high coolant requirements and geometry constraints limit the possible arrangement of the multiple rows of film cooling holes in the so-called showerhead region. In the past, investigators have tested many different showerhead configurations by varying the number of rows, inclination angle, and shape of the cooling holes. However, the current leading edge cooling strategies using showerheads have not been shown to allow a further increase in turbine temperature without the excessive use of coolant air. Therefore, new cooling strategies for the first vane have to be explored. In gas turbines with multiple combustor chambers around the annulus, the transition duct walls can be used to shield, i.e., to protect, the first vane leading edges from the high heat loads. In this way, the stagnation region at the leading edge and the showerhead of film cooling holes can be completely removed, resulting in a significant reduction in the total amount of cooling air that is otherwise required. By eliminating the showerhead the shielding concept significantly simplifies the design and lowers the manufacturing costs. This paper numerically analyzes the potential of the leading edge shielding concept for cooling air reduction. The vane shape was modified to allow for the implementation of the concept and nonrestrictive relative movement between the combustor and the vane. It has been demonstrated that the coolant flow that was originally used for cooling the combustor wall trailing edge and a fraction of the coolant air used for the vane showerhead cooling can be used to effectively cool both the suction and the pressure surfaces of the vane.