A Non-Dimensional Consideration in Combustor Axial Stress Computations
Thermal stresses in the combustor of gas-turbines are computed using non-dimensional parameters. Buckingham pi theorem was used to arrange the listed relevant parameters into non-dimensional groups. In testing the validity of the functional relation of the non-dimensional independent parameters, use is made of the prevailing temperatures of the combustor in operation. A computer program was used to enhance computations. The results showed an interesting way of influencing the axial stresses. To reduce stresses in gas-turbine combustors, a method of varying the independent parameter that is of radius ratio oriented and thickness dependent was adopted. This showed a reduction of the axial stresses to minimal levels using the parameters. Plots were made and a point of inflection that manifested itself in the presentation of the axial stress function was further investigated upon. It turned out to be a point of abnormal stress level and out-of-trend temperature profile. The use of non-dimensional consideration proved adequate in the computation of axial stresses. The results showed a 2 percent difference from existing values of stresses got from a transient thermal loading of a combustor.
Influence of Convection Heat Transfer Coefficient on Heat Transfers and Wall Temperatures of Gas-turbine Combustors
The effect of convection heat transfer coefficient on the combustor liner surface temperatures and the amount of heat that is transferred through the combined effect of radiation, convection and conduction at the surface is investigated. A computer program using pertinent parameters as input was used to handle the heat transfer computations. The results were impressive, showing how the internal and external surface temperatures are affected by varying the coefficient of convective heat transfer. The higher the coefficient, the higher the quantity of heat transferred. Higher wall temperatures are achieved with higher coefficients. But temperature difference between liner outer and inner wall surface temperatures gets larger with increased coefficients. The quantity of heat that could be expected by variation of the convection heat transfer coefficient is in the range of 70,000- 85,000KJ.
Mechanical and thermal stresses of a functionally graded circular hollow cylinder with finite length
By using a multi-layered approach based on the theory of laminated composites, the solutions of temperature, displacements, and thermal/mechanical stresses in a functionally graded circular hollow cylinder are presented in this paper. The cylinder has finite length and is subjected to axisymmetric thermal and mechanical loads. The material properties are assumed to be temperature-independent and radially dependent, but are assumed to be homogeneous in each layer. As an illustration, the numerical results for a mullite/molybdenum functionally graded circular hollow cylinder are also presented.