Mechanical Engineering Department
BS in Mechanical Engineering
The following report documents a California Polytechnic State University, Mechanical Engineering Senior Project sponsored by the gas turbine manufacturer, Solar Turbines. The senior project team consisted of four senior mechanical engineering students at Cal Poly, all with general concentrations; Ryan Bruce, Carolyn Honeycutt, Steve Oltrogge, and Emmett Ross. Kenneth Thomas sponsored the group and serves as the point of contact between the senior project team and Solar Turbines. He is a member of the Solar Turbines Mechanical Design Engineering Team and a Cal Poly graduate. Christoph Maurer served as the project team’s on-campus advisor.
A gas turbine uses internal combustion to produce output shaft work and can be broken down into a “cold” section and a “hot” section. The cold section is composed of the air inlet and the air compressor, while the hot section is composed of the burner, turbine, and diffuser. This project was focused on the compressor, specifically compressor blade installation. Solar Turbines’ T130, Mars, and T250 turbines all contain multi-stage compressors, meaning that many sets of compressor blades spin around a single shaft to continually compress the air as it nears the burner. Many of the compressor stages are installed using a ring method, where the compressor blades are slid into large slots around the compressor rotor, radially, and held into place, axially, by a large ring. These stages require additional hardware to restrain the blades radially. However, the first several stages of the compressor use axially installed fan blades, where each blade slides into an individual slot on the rotor disk and is held in place, radially by the geometry of the compressor. These stages therefore require additional hardware to restrain the axial movement of the blades. This is accomplished via small steel retainer tabs. This project focuses on the installation of these metal retainer tabs.
The current process for installing the early stage compressor blades, those requiring retainer tabs, involves several, individual, time-consuming steps. Additionally, there are numerous tools required for each of these steps and every individual installation technician can have an additional, personal set of installation tools. As a result compressor blade installation is a lengthy and imprecise process that leads to inconsistencies and risks damaging the compressor rotor. The task for the Cal Poly senior project group was to design a tool(s) and a corresponding standardized process to bend these retainer tabs into position. The sponsor, Solar Turbines, owns all Intellectual Property for the tools designed during the course of the project. In return, they provided funding for the project, access to necessary company proprietary information, manufacturing support (as needed), and general project guidance.
The overall aim of this project was to design a tool or set of tools that removed as much of the variation from compressor blade retainer tab installation as possible. As well as reduced the time spent installing blades, therefore reducing the risk of damage to the turbine blades and rotors from non-standardized processes and tooling. Additionally the team focused on minimizes the number of tools used in the overall process. The final tool design consisted of two tools, a “backing” and a “bending” tool. Each should decrease the installation time, increase consistency, are more ergonomic, and are safer than the current methods.