William G. Sheridan

De-Oiler System for Improved Oil Containment

Oil containment is a critical design requirement that affects overall system safety and reliability of gas turbine engines. This paper examines a new method to enhance oil containment by use of an improved de-oiler that creates a favorable bearing compartment differential pressure environment even at low power settings. Typically gas turbine engines require seals to contain oil within the bearing compartment. These seals, both contacting and non-contacting configuration styles, rely on secondary airflow to buffer the sealing interface and force oil mist and droplets back into the compartment. This is not difficult to achieve at high or moderate power conditions since there is generally sufficient air flow and pressure available to meet the sealing requirements. However, at idle conditions, the engine low-pressure compressor (LPC) may not turn fast enough to produce sufficient airflow to buffer the seals. To address these concerns the authors propose a method where the de-oiler creates a vacuum at idle speed, which results in favorable compartment seal differential pressures and also acts as a restrictor at higher speeds, where limiting the contact pressure and increasing the service life of mechanical seals become desirable design goals. The paper will examine a specific case study with both analytical and experimental results.Copyright

Design Optimization Study of Isolation Mount Systems for Gas Turbine Engine Accessories

Design optimization has become increasingly important in today’s world. The ability to develop products that offer the best possible solution, distinguish industry leaders from those that lag behind. To reach this goal, optimization techniques are required which provide solutions in a timely and cost effective manner. This paper addresses a specific optimization process for designing isolation mount systems for gas turbine engine accessory components. This process enables the designer to quickly select an isolation system that will reduce the loads on components without the use of a time consuming Finite Element Analysis (FEA). Commercially available tools such as MATLAB [7] and MSC-WORKING MODEL 2D [6] are used to study a range of mount systems and help the designer focus his attention on the best choice of design variables. Gas Turbine engine accessory mount systems are generally sized by emergency conditions such as Fan Blade Out (FBO). These emergency conditions are rarely seen in service, but since they can drive the cost and weight of the mount system, an optimization process is needed to select the best configurations. References [8] through [10] discuss this in detail. Design Cycle time is just as important as cost and weight. The ability to size and package components quickly and accurately is vital to the design process. Poor utilization of space can drive cost and weight as much as poor component design. Knowing the correct size of the mount system in a rapid fashion offers further opportunities for surrounding components & systems to be optimized.© 2005 ASME