Abstract:
Gas turbine engines encompass a wide range of applications ranging from electricity production to aircraft propulsion. The air is raised to a high temperature and pressure which then is fed to a turbine where it expands to a lower pressure thereby imparting rotational energy to the turbine blades. The air at exhaust produces a thrust which is utilized in applications such as a turbojet engine. The turbine may comprise of several stages depending on the intake pressure such as a high-pressure turbine stage (HPT) or a low-pressure turbine stage (LPT). The purpose of an LPT is to extract the energy remnants from the exhaust air leaving the HPT. Since the LPT intakes air at a lower pressure and a higher volume, this ultimately results in the LPT being larger in size and weight. The turbine blade therefore being larger is more prone to vibrate. These vibrations along with the combined effect of centrifugal stresses and high temperature can make the blade susceptible to failure. A solution to this problem can be achieved if the vibrational characteristics of the blade are known. This is accomplished through modal analysis that basically is a measure of structure’s inherent response when subjected to vibrations. The goal of this project is to analyze the modal parameters (natural frequency, mode shape) of various materials. The analysis will be carried out computationally using a commercial FEA package such as ANSYS and the results will be validated by the values obtained from the mathematical model. The obtained values of natural frequency relate to the material stiffness and mass. These results will help us in finalizing our choice regarding the blade materials suitable for operation that not only possess high stiffness but are also light in weight thus reducing the overall turbine weight.
