Influence of operating conditions on thermal requirements in gas turbine blades

<div class="section abstract"><div class="htmlview paragraph">Gas turbines are thermal machines with applications in various areas, such as in the transportation and power generation sector, and in various engineering fields. The overall performance of such equipment can be improved by increasing the allowable thermal limit on the blades of its rotors through internal cooling technologies. By means of a thermodynamic modeling of the process and the use of the finite difference method, it was possible to evaluate how the mass flow of air diverted from the compressor, pressure ratio, environmental conditions, the efficiencies and conditions of the equipment that compose the turbine, affect the thermal demands of gas turbines. With the study in question, it was possible to estimate the maximum temperature at which turbine blades will be subjected and at what locality this fact will occur. The maximum temperature of the gas turbine is one of the factors limiting the maximum power that the turbine can offer. Higher values for compression ratio are desirable in gas turbine, since they allow higher efficiencies, however, higher becomes the average blade temperature, causing an increase of thermal load on the components of the expansion turbine, especially in the blades of the first stage, because they are in direct contact with the hot gases leaving the combustion chamber. On the other hand, by varying the cooling flow, from 10% to 20% of the incoming mass flow of the compressor, it was possible to verify that the blade obtained a cooling of up to 130K. In addition, excess air and its inlet thermal conditions, as well as the type of fuel used, have a major influence on turbine thermal requirements. These results are therefore of great value, when what is desired for the gas turbines are intelligent cooling techniques, lower maintenance costs and longer service life.</div></div>