Matching Items (2)
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Description
This thesis is concerned with off-design performance of gas turbines using the program GasTurb12. The thesis provides basic background research into gas turbine performance and an extensive discussion about off-design performance. The program GasTurb12 is used to perform design point calculations to verify the program against known textbook results and

This thesis is concerned with off-design performance of gas turbines using the program GasTurb12. The thesis provides basic background research into gas turbine performance and an extensive discussion about off-design performance. The program GasTurb12 is used to perform design point calculations to verify the program against known textbook results and to perform a detailed off-design analysis based on a formulated problem statement. The results in GasTurb12 showed good correlation with the textbook results and the detailed off-design analysis provides valuable information about gas turbine design. An implementation strategy has been suggested to not only research further uses of GasTurb12, but also to incorporate it into undergraduate curriculum. It is recommended to further evaluate the capabilities of GasTurb12 to verify the program with real gas turbine systems.
ContributorsMartinjako, Jeremy Chey (Author) / Trimble, Steven (Thesis director) / Takahashi, Timothy (Committee member) / Middleton, James (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2013-05
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Description
Gas turbine efficiency has improved over the years due to increases in compressor

pressure ratio and turbine entry temperature (TET) of main combustion gas, made viable

through advancements in material science and cooling techniques. Ingestion of main

combustion gas into the turbine rotor-stator disk cavities can cause major damage to the

gas turbine. To

Gas turbine efficiency has improved over the years due to increases in compressor

pressure ratio and turbine entry temperature (TET) of main combustion gas, made viable

through advancements in material science and cooling techniques. Ingestion of main

combustion gas into the turbine rotor-stator disk cavities can cause major damage to the

gas turbine. To counter this ingestion, rim seals are installed at the periphery of turbine

disks, and purge air extracted from the compressor discharge is supplied to the disk

cavities. Optimum usage of purge air is essential as purge air extraction imparts a penalty on turbine efficiency and specific fuel consumption.

In the present work, experiments were conducted in a newly constructed 1.5-stage

axial flow air turbine featuring vanes and blades to study main gas ingestion. The disk

cavity upstream of the rotor, the 'front cavity', features a double seal with radial clearance

and axial overlap at its rim. The disk cavity downstream of the rotor, the 'aft cavity', features a double seal at its rim but with axial gap. Both cavities contain a labyrinth seal radially inboard; this divides each disk cavity into an 'inner cavity' and a 'rim cavity'.

Time-averaged static pressure at various locations in the main gas path and disk

cavities, and tracer gas (CO2) concentration at different locations in the cavities were

measured. Three sets of experiments were carried out; each set is defined by the main air flow rate and rotor speed. Each of the three sets comprises of four different purge air flow rates, low to high.

The mass flow rate of ingested main gas into the front and aft rim cavities is

reported at the different purge air flow rates, for the three experiment sets. For the present stage configuration, it appears that some ingestion persisted into both the front and aft rim cavities even at high purge air flow rates. On the other hand, the front and aft inner cavity were completely sealed at all purge flows.
ContributorsMichael, Mukilan Sebastiraj (Author) / Roy, Ramendra P (Thesis advisor) / Mignolet, Marc P (Thesis advisor) / Phelan, Patrick (Committee member) / Arizona State University (Publisher)
Created2015