Abstract Title

Preliminary Optimization Study of Conventional Rib Turbulators for Cooling in Gas Turbine Blades

group

Authors' Class Standing

Isheeta Ranade, Junior Jaime Gutierrez, Senior

Lead Presenter's Name

Isheeta Ranade

Faculty Mentor Name

Dr. Mark Ricklick

Abstract

Preliminary Optimization Study of Conventional Rib Turbulators for Cooling in Gas Turbine Blades

Gas turbines are largely used to power most passenger aircrafts today and are considered to be a solution to the power requirement issues we face today. The efficiency levels of gas turbines has increased continuously over the years, thus contributing to their success. Research suggests that as the turbine inlet temperature increases, the overall thermal efficiency and power output of the engine increases. Gas turbines nowadays are capable of producing inlet temperatures in the range of 1500-1700 °C. However, the materials that the blades are made out of cannot handle such high temperatures and start melting around 1300 °C. This creates a need for developing cooling technologies that will effectively cool the blades without damaging them. The focus of this study is to optimize the existing internal cooling designs in order to further improve the thermal efficiency and power output of gas turbines. There are various ways in which turbine blades are internally cooled. Some of the methods include the use of pin- fins, impingement, and rib turbulators. This study focusses on internal cooling using rib turbulators.

Method

A single rectangular parameterized rib was created and analyzed using STAR-CCM+, and it served as a baseline model. The thermal efficiency in terms of pressure loss was analyzed for this model. Since the purpose was to optimize a single rib, the model consisted of a single rectangular rib. Next, parameterized rectangular and triangular geometries were created such that the lengths of the rectangle and triangle could be varied over a specified range. For the triangle, besides the lengths, the angles and the pitch angle could also be varied. Using an optimization software called Optimate+, both the geometries were optimized and the three best performing designs were chosen to be tested in the wind tunnel.

Results

A total of 17 designs were obtained without error. Thermal efficiency was calculated using Dittus Boelter method and comparing the results with a conventional rectangular rib. A maximum of 1.4 efficiency was obtain for the best design. Some of the features that improved the thermal efficiency were bottom pockets as well as the rib not being in contact with the side wall. Pockets in V shape in the center of the rib also improved the flow mixing behind the rib and reduced the flow separation distance.

Conclusion

This preliminary study helped prove that single parameterized ribs can indeed be optimized to obtain better performing designs with improved thermal efficiencies. On analyzing the designs it was realized that they performed better than the baseline model due to their various new features such as gaps, side pockets, and V- pockets, among others. The next step in this study is to manufacture these optimized designs using 3D printing and validate them experimentally by carrying out wind tunnel tests.

Did this research project receive funding support (Spark or Ignite Grants) from the Office of Undergraduate Research?

Yes

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Preliminary Optimization Study of Conventional Rib Turbulators for Cooling in Gas Turbine Blades

Preliminary Optimization Study of Conventional Rib Turbulators for Cooling in Gas Turbine Blades

Gas turbines are largely used to power most passenger aircrafts today and are considered to be a solution to the power requirement issues we face today. The efficiency levels of gas turbines has increased continuously over the years, thus contributing to their success. Research suggests that as the turbine inlet temperature increases, the overall thermal efficiency and power output of the engine increases. Gas turbines nowadays are capable of producing inlet temperatures in the range of 1500-1700 °C. However, the materials that the blades are made out of cannot handle such high temperatures and start melting around 1300 °C. This creates a need for developing cooling technologies that will effectively cool the blades without damaging them. The focus of this study is to optimize the existing internal cooling designs in order to further improve the thermal efficiency and power output of gas turbines. There are various ways in which turbine blades are internally cooled. Some of the methods include the use of pin- fins, impingement, and rib turbulators. This study focusses on internal cooling using rib turbulators.

Method

A single rectangular parameterized rib was created and analyzed using STAR-CCM+, and it served as a baseline model. The thermal efficiency in terms of pressure loss was analyzed for this model. Since the purpose was to optimize a single rib, the model consisted of a single rectangular rib. Next, parameterized rectangular and triangular geometries were created such that the lengths of the rectangle and triangle could be varied over a specified range. For the triangle, besides the lengths, the angles and the pitch angle could also be varied. Using an optimization software called Optimate+, both the geometries were optimized and the three best performing designs were chosen to be tested in the wind tunnel.

Results

A total of 17 designs were obtained without error. Thermal efficiency was calculated using Dittus Boelter method and comparing the results with a conventional rectangular rib. A maximum of 1.4 efficiency was obtain for the best design. Some of the features that improved the thermal efficiency were bottom pockets as well as the rib not being in contact with the side wall. Pockets in V shape in the center of the rib also improved the flow mixing behind the rib and reduced the flow separation distance.

Conclusion

This preliminary study helped prove that single parameterized ribs can indeed be optimized to obtain better performing designs with improved thermal efficiencies. On analyzing the designs it was realized that they performed better than the baseline model due to their various new features such as gaps, side pockets, and V- pockets, among others. The next step in this study is to manufacture these optimized designs using 3D printing and validate them experimentally by carrying out wind tunnel tests.