Aerodynamic noise in aero-engine LP turbines - Application of CFD techniques

Introduction In the following, an introduction to the research performed in this thesis is provided. The motivation of the growing interest on aircraft and aero-engine noise is given, as well as a general overview of the techniques applied, in an industrial perspective, for turbomachinery acoustic design. I. Background and motivation Aircraft noise is a growing problem for communities near airports. Air traffic is constantly increasing and is expected to increase even faster over the next years. This implies the number of airports and the extension of airport areas will increase, as well as the number of flights from each airport. This means that the concern about airport noise will involve more people, and the demand for quieter aircrafts will keep increasing. Noise pollution associated with take-off and approach may cause physical or psychological harm and studies have associated excessive noise with sleep deprivation, high blood pressure, and poor learning habits of children. In some cases, airports are paying millions of dollars to soundproof school classrooms to avoid being sued. Residential real estate and other properties surrounding airports are seeing declines in value as a result of aircraft noise. To assist with the problems, airports are cooperating to change flight procedures for take-off and landing. For example, pilots can only use certain amounts of thrust at take off and they must be at certain altitudes to make certain manoeuvres. Nevertheless noise reduction targets cannot be reached by improving aircraft traffic management alone. Noise reduction at source has to be considered, and here aircraft and engine manufacturers will still play a fundamental role. This is still more evident, as one thinks that aircraft noise regulations are becoming even more stricter.