CATE has a proven track record of co-ordinating and executing field trials at airports. Integrating airside and landside measurements, successful campaigns have been run at large commercial airports such as Heathrow and Manchester. In addition, specialist field work aimed at establishing the physics of aircraft plume dispersion has been undertaken with FAAM at Cranfield, and on-the-wing engine emission testing has been undertaken in association with BAMC. With over 30 years of experimental field campaign expertise and proven experimental facilities, CATE is one of the leading groups in the UK for air transport research. Facilities include:
This fully autonomous, vehicle-mounted system is used to map exhaust emission plumes, providing detailed and time-sequenced cross-sections through the plume so that dispersion processes and the interaction with the ground may be studied. The system is built around a 30 Hz frequency-tripled Nd:YAG laser emitting radiation at a wavelength of 355 nm. This wavelength is well scattered by plume aerosols, but crucially it cannot penetrate the cornea and so eye-safe operation may be achieved.
Co-located with the Lidar is a 10 m instrumented meteorological mast to record wind speed, wind direction, temperature and relative humidity. Additionally, screen-height temperature, relative humidity and short wave insolation are measured and logged.
The Doppler Lidar system uses a heterodyne technique to measure the Doppler shift of an eye-safe infra-red beam (λ = 1.5 μm) scattered by ambient aerosol in the atmosphere. It thus provides radial profiles of turbulence and mean wind speeds along the line of fire of the beam. We also have access to a Scintec Model SFAS64 Doppler Sodar (an acoustic sounding system), which provides boundary -layer sounding.
The resolution of these particle counters is 0.01 μg m-3 for PM1 and PM2.5 and 0.1 μg m-3 for PM10 and TSP, with a sampling rate of 1 Hz on each channel and on-board logging. As the instruments are based on real-time counting and sizing of particles the resolution is invariant with respect to averaging time. Wind speed and direction are measured simultaneously.
. These point sampling systems are used to collect an atmospheric sample of sufficient size that it may be chemically characterized, e.g. for the analysis of PAH content, or by SEM-EDX (see below).
. With these detectors, chemical species with a first ionization potential of less than 10.2 eV (typically unsaturated hydrocarbons) are sampled at 50 Hz. This provides information on the small-scale structure of the plumes. Alternatively, the UVICs can be configured in an ion-only collection mode for the detection of chemi-ions in a plume.
The SEM instrument in the Dalton Research Institute is a state-of-the-art facility with ultimate beam size of 1 nm and electron energy down to 100 eV. Attached analytical facilities include micro-Raman and optical micro Raman for molecular analysis and wave dispersive and energy dispersive X-ray analysis for elemental imaging.
This is used for engine emissions testing. The sampling probe is typically positioned around one nozzle diameter from the exit plane of the engine. Computer-controlled transverse movement of the probe tip allows exhaust emissions from across the engine and bypass air exit plane to be sampled. Position sensing and feedback mechanisms are in place to allow for the movement of the aircraft at higher powers. The sampling rake is fitted with a heated probe head, tip dilution and heated sampling line to maintain the sample condition during transfer to the analysis instrumentation.
. Designed to be used in conjunction with the transverse sampling rake, the gas analysis lab collects and logs data includes smoke number, unburned hydrocarbons (UHC), carbon monoxide (CO), carbon dioxide (CO2), oxides of nitrogen (NOx) and of sulphur. In addition, soot samples are collected for later analysis.
. Modern analytical laboratory for the determination of fuel properties: aromatic / aliphatic fractions, fuel sulphur, etc.