Overview
A large role in the efficiency of the overall engine is played by the fan and bypass system. Lightweight, effective acoustic liners will be required to meet both the weight and noise emissions requirements. This presents an opportunity to develop the state of the art in intake liner acoustic and mechanical design and to test this liner in the engine environment.
This proposal partook in the acoustic optimization, mechanical design and manufacture of a novel aeroengine intake liner that aims to reduce the cost, weight, durability and improve acoustic attenuation performance.
Previous EU funded projects that Bombardier Aerospace Belfast (BAB) has been involved in, such as FANPAC and SILENCE(R), have identified the potential for superior acoustic performance with acoustic treatments having a Non Linearity Factor (NLF) in the range 2.0 to 2.5. Considering this as a design objective, BAB has been developing zero splice micro-perforate composite acoustic liner facing sheets.
This technology provides significant flexibility and benefits for acoustic liner design. These benefits include NLF covering the complete target range, and more (2.0 to 5.0), uniform or varying impedance in any direction without hard-wall splices, single or double degree of freedom acoustic treatments and zero-splice intake acoustic liner designs.
The objective of this proposal was to elevate micro-perforate acoustic liner technology from TRL4 to TRL6. This involved the manufacture of a full scale, zero-splice micro-perforate composite engine intake acoustic liner. This process addressed challenges such as tooling design, component manipulation for laser drilling and the application of the technology to large diameter nacelles.
[DoW Rev.1: Micro-perforate has been replaced with 1.2mm diameter mechanically drilled holes due to the results of the research showing that laser drilling was not currently feasible]
Complimentary studies were also performed to optimise the design through testing to evaluate the degradation of composite material properties due to UV degradation and experiments to determine rain erosion properties of micro-perforate acoustic treatments.
Funding
Results
Executive Summary:
The proliferation of air travel and its forecast of an ever increasing global trend brings many benefits in terms of business, trade and leisure for the world’s population, but is not without challenges which need to be overcome to ensure that the local community and greater population can prosper and succeed in the wider context of the advancing travel and transport industry.
A key design driver for the aviation industry is the improvement and refinement of aircraft efficiency and environmental impact which are increasing in importance as the industry grows. More stringent regulations are resulting in the industry developing new technologies and methodologies to ensure that these challenges are overcome. To comply with these requirements airlines and aerospace manufacturers are increasingly targeting noise reduction, weight and production costs to achieve these goals and are key parameters for this project.
Noise generated during aircraft take-off and approach operations is a particular issue for local communities that are in close proximity to airports. In turbofan engines, the ducts are lined wherever possible with acoustic panels, for the reduction of radiated noise. The advancement of engine technology has resulted in the noise produced from an engine, and in particular the main fan blades, being significantly different than previous generations of turbofan jet engines.
This has resulted in the need to better study, analyse and evaluate inlet acoustic liners for new and future generation large scale turbofans that will dominate aircraft in the decades to come and ensure that inlet acoustic liners can be adequately designed and optimised to meet current and future aircraft noise regulations.
The main objective of this project was to develop the design and manufacturing capability of advanced acoustic liner and inlet assembly technology in line with the need to achieve environmental and aircraft efficiency targets and provide an opportunity to progress a productionised solution for future applications.