A descriptive account on the efficiency as well as robustness of gas turbines has been provided in this book. Various topics regarding the evaluation of gas turbines and their engineering operations are presented in the book. Methodical and experimental procedures are utilized to classify failures and quantify operating circumstances and efficiency of gas turbines. Some topics included in this book are gas turbine engine flaws, diagnosis and condition monitoring systems, operating conditions of open gas turbines, reduction of jet mixing noise, recovery of exhaust heat from gas turbines, apt substances and coatings, ultra micro gas turbines and operations of gas turbines. The exchange of scientific outcomes and ideas in this book will result in an advanced reliability on gas turbines.