Versatile Fluid Measurement System for Aerospace Research

Meeting the UK's ambitious 2050 emissions targets will require ambitious research programmes capable of creating a step change in the efficiency of engineering systems. The aim of the Aerospace Engineering Research Centre (AERC), at the University of Bath, is to realise this goal through aerodynamically efficient aircraft and cleaner gas turbine engines. These traditionally separate research strands have grown increasingly interdisciplinary requiring greater collaboration and new research methodologies.

One of the principle challenges facing both these research fields is the measurement of velocity and species concentration; these quantities are invisible to the naked eye but vital in understanding the flow physics. To circumvent this problem the flow can be seeded and the material tracked thus making the invisible, visible. This proposal will provide the AERC with a Versatile Fluid Measurement System (VFMS) for concentration, velocity, temperature and deformation measurements that is unique worldwide. This capability is absolutely state of the art and will be further developed by the AERC to create new measurement possibilities in the fields of aerodynamics and gas turbine research.

An aircraft in turbulence is familiar to any passenger, however the problem associated with gusts and turbulence goes far beyond mere discomfort. The aircraft engineers must take account of these load scenarios during the aircraft design process. As the largest loads are experienced during gusts, turbulence and extreme manoeuvres these scenarios tend to dictate the aircraft's structure, and therefore its weight, even though they are very rare occurrences. In the AERC we are developing both improved gust alleviation strategies that will allow for lighter, more fuel efficient, aircraft and more accurate design tools that will reduce aircraft development time and encourage innovation in the design process.

Gas turbines are predominantly used for aircraft propulsion and industrial power generation. Previous research and development has resulted in gas turbines that operate at extremely high speeds and beyond the melting point of the components themselves. To control these extreme temperatures requires the bleeding of cold air from the low-temperature compressors to create a coolant film over the high-temperature turbine components. Efficient use of this coolant directly impacts on the efficiency of the turbine but its interaction with the mainstream gas path is still poorly understood. There is therefore great scope for improvement. This equipment will be used for world-first non-intrusive measurements to trace the three-dimensional secondary gas path and its interaction with the mainstream flow and to derive 2D temperature maps of the rotor surface. This information will be directly compared with computational simulations and be used to improve gas turbine efficiency.

Economic Impact
The primary economic impact is in the aerospace and industrial gas turbine sectors. The UK aerospace sector is the largest in Europe and second largest in the world. It supports 230,000 jobs across the UK and contributes £24.2bn p.a. to GDP and is forecast to grow substantially. To ensure this growth occurs in the UK, a recent policy document reported that a step change in technology is required to maintain our competitive advantage and achieve the 2050 efficiency targets. One of the four key areas described as critical is novel aerodynamics which fits exactly with research programmes A and B. The outcomes from these programmes will feed directly into Airbus UK. Airbus UK is one of the largest contributors to the aerospace sector, directly employing 13,000 and indirectly employing a further 87,000. The industrial gas turbine sector is represented by Siemens Industrial Turbomachinery in Lincoln which employs 1,600 to design, manufacture and maintain small gas turbines (5-15 MW) for the world market. In addition to the direct employment within Lincoln, where the high-value employment bring over £48M into the local economy, the business generated by Lincoln supports a supply chain providing goods and services worth over £160M to the UK as a whole.

Societal Impact
To meet the legally binding climate act targets the UK must reduce its CO2 emissions at a rate of approximately 2% p.a. To achieve this rate will require significant applied innovation in all sectors. Electricity supply is the largest sector at 35% of this total. Nevertheless it is also a sector experiencing significant reductions (1.25% p.a.) primarily due to the switch from 'dirty' coal to natural gas and growth in renewable energy. The current proposal will accelerate this reduction by enabling fundamental gas and wind turbine research. In the case of gas turbines, end-wall profiling has the potential to deliver a very significant increase in efficiency of 1.4%. In the case of wind power, high-frequency gust alleviation is a viable method of improving reliability for both on-shore and off-shore wind farms and has therefore been highlighted as a high-priority medium-term research action by the European Wind Energy Technology Platform. Given the growth forecasts for the UK gas turbine and wind energy sectors now is the time to make the investment in this novel research. By contrast aviation is a small contributor, 6%, but the only sector experiencing substantial growth: 100% increase in 20 years. How to curb this growth is currently in negotiation but is likely to require a 2% improvement every year until 2050. To achieve 2% p.a. will require radical rather than incremental improvements between generations of aircraft. There is therefore significant environmental, economic, and societal incentives for both the UK government and UK aerospace sector to take measures now to enable more efficient aircraft in the near future.

Industrial Impact
The AERC approach is to collaborate with major industrial aerospace partners, ensuring that the results of research are successfully integrated and have a positive impact on the future success of the sector. The programmes described in the case for support include Siemens UK, Airbus UK and the US Air Force Research Laboratory (AFRL) as partners. Siemens are likely to benefit through research programmes C and D. The simulated 1.4% improvement will be of significant benefit to Siemens UK and support UK jobs as described above. Airbus UK will benefit through research programme A and B. This research the potential to give the competitive edge in the drive for ever more efficient aircraft. The AFRL will benefit through canonical unsteady aeroelastic results for validation of novel CFD codes. As a government research body AFRL are primarily an academic partner but they do have a strong influence over the US aerospace sector and are a primary driver in the development of new Computational Fluid Dynamics codes.