Understanding the Responses of a Metal and a CMCTurbine Blade during a Controlled Rub Event using a Segmented Shroud

Commercially available CMCs, or ceramic matrix composites, provide several benefits over metal blades including weight and increased temperature capability, which may save performance by significant reduction of the cooling flow bled from the compressor. The turbine inlet temperature has consistently increased over the past 70-years. Materials like CMC are typically used in areas such as the LPT, or low-pressure turbine, where reliability at high-temperatures beyond the capability of metal blades will be needed as the desire for higher performance capability increases. As part of a co-operative research program between GE Aviation and the OSU Gas Turbine Laboratory, the response of a CMC stage 1 LPT blade has been compared with the response of a comparable metal blade using the OSU GTL large spin pit facility, LSPF as the test vehicle. Load cell mounted on the casing wall, strain gages mounted on the airfoils, and other instrumentation is used to assess blade tip rub interactions with the stationary casing. The intent is to measure the dynamic response of both the CMC and the metal blades with the turbine disk operating at design speed and with representative incursion rates and depths. This thesis will explore these responses and compare the CMC results to typical metal blades to assess the operability of CMC blades during and after a tip rub.There are currently many papers being published related to the performance of ceramic matrix composites as this material seems to have the ability to cover both the high stresses and high temperatures of the ever complex engine environment. There are papers dealing with combustor liners, nozzles, casings, as well as blades. This thesis will focus on the mechanical behavior of the blade when operating at tight clearances ultimately resulting in a tip rub event.In summary, the tip rub event has been evaluated in this thesis showing a distinct comparison between the CMC blade and the conventional metal turbine blade. Shoe wear or casing wear and blade tip wear are both characterized for several types of rub conditions including a light, medium, and heavy rub. For each condition, the rub primary dynamic modes have been evaluated, as well as an approximation of the blade tip loads has been calculated.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor dc:publisher

The Ohio State University

Year dc:date

2013

Author dc:creator

• Langenbrunner, Nisrene A.

Contributors dc:contributor

• Dunn, Michael

• Aerospace Engineering
• Materials Science
• "tip rub"
• CMC
• OSU
• "Gas Turbine Lab:
• GTL
• "turbine blades"
• "turbine blade tip rub"

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: some rights reserved. It is licensed for use under a Creative Commons license. Specific terms and permissions are available from this document's record in the OhioLINK ETD Center.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=osu1366191740

OAI identifier oai:identifier

oai:etd.ohiolink.edu:osu1366191740