Computer based mathematical models describing the aircraft evacuation process have a vital role to play in aviation safety. However, such models have a heavy dependency on real evacuation data in order to (a) identify the key processes and factors associated with evacuation, (b) quantify variables and parameters associated with the identified factors/processes and finally (c) validate the models. The Fire Safety Engineering Group of the University of Greenwich is undertaking a large data extraction exercise from three major data sources in order to address these issues. This paper describes the extraction and application of data from one of these sources — aviation accident reports. To aid in the storage and analysis of the raw data, a computer database known as AASK (aircraft accident statistics and knowledge) is under development. AASK is being developed to store human observational and anecdotal data contained in accident reports and interview transcripts. AASK comprises four component sub-databases. These consist of the ACCIDENT (crash details), FLIGHT ATTENDANT (observations and actions of the flight attendants), FATALS (details concerning passenger fatalities) and PAX (observations and accounts from individual passengers) databases. AASK currently contains information from 25 survivable aviation accidents covering the period 4 April 1977 to 6 August 1995, involving some 2415 passengers, 2210 survivors, 205 fatalities and accounts from 669 people. In addition to aiding the development of aircraft evacuation models, AASK is also being used to challenge some of the myths which proliferate in the aviation safety industry such as, passenger exit selection during evacuation, nature and frequency of seat jumping, speed of passenger response and group dynamics. AASK can also be used to aid in the development of a more comprehensive approach to conducting post accident interviews, and will eventually be used to store the data directly.

A method for performing three-dimensional, multipoint, lift-constrained drag minimisation for complex aircraft configurations is presented. Parameters representing the aircraft geometry are the design variables used in the solution of an optimisation problem. The compressible Euler equations for the flow are discretised on automatically generated unstructured meshes, and the sensitivities of the objective function and the constraints with respect to the design parameters are efficiently calculated using the discrete adjoint method. In addition, the solution algorithm has been parallelised making the approach feasible for practical applications. Several constrained minimisation strategies are discussed and some numerical tests are carried out for a lift-constrained, two-dimensional problem. The strategy found to work best is demonstrated for the three-dimensional optimisation of a wing-body configuration operating in transonic and supersonic conditions. It is concluded that Euler-based optimisation can be useful as a first step in the design process but that most applications involving transonic flows do require viscous flow modelling to avoid unrealistic pressure distributions.

An experimental investigation has been performed into the free jet and wall jet characteristics of high pressure ratio coaxial jets operating with inverted velocity profiles and impinging onto a ground plane. Pitot-static probes have been used to record free jet properties at various distances from the jet exit plane, and wall jet properties of the impinging jets at various radial positions. Jet properties such as velocity decay and spreading rates were calculated and compared to published literature. Wall jet development was investigated and recorded. Inner and outer nozzle pressure ratio (NPR) were altered to give a range of jet exit conditions. The results obtained showed variations in the wall jet properties as jet exit conditions were altered, but wall jet self-similarity was found and varying either nozzle height above the ground plane or NPR did not alter this. Free jet data showed large variations in behaviour with changes in NPR. The inverted profile jets behaved similarly to annular jets, showing similar characteristics. Inner jet pressurisation was observed for inverted profile jets and also significant acceleration of the flow from the inner, lower NPR, jet when this was subcritical.

Experiments have been conducted to investigate the flowfield associated with two co-rotating vortices which represent the idealised vortex system associated with a novel rotor blade tip planform. These vortices were generated by two rectangular NACA 0015 half wings positioned upstream of the working section of a low speed windtunnel. Hot-wire measurements were conducted downstream of the generators using X-wire probes to document the strength, position and size of the vortices. A numerical model was utilised to provide an accurate means of determining vortex strength, position and size. Finally, the model was successfully extended to consider the rotation of the vortex system.

Reliable measurements of unsteady pressure on the surface of thin aerodynamic bodies in low subsonic, unsteady flows were made using small piezoelectric transducers. The hand-made transducers, calibrated against a B&K microphone for use in experiments, were used in two sets of low speed experiments. The first set involved a stationary aerofoil encountering a rotating, periodic gust as would be present in a rotor-stator interaction. The second set involved an instrumented propeller operating behind a stationary cyclic distortion as would be present behind stators or guide vanes. In both sets of experiments, reliable measurements of the small unsteady pressures on the body surfaces were made despite difficult experimental environments.

Inviscid and viscous computational models have been used to predict two-dimensional steady separated flow around an aerofoil with a spoiler. First, an attempt is made to construct an inviscid panel method in which piece-wise linear vortex panels are placed on the aerofoil and spoiler. The separated region is modelled with potential flow analysis by using free vortex sheets placed on the separation streamline from the spoiler tip and aerofoil trailing-edge. The shapes of the vortex sheets require an iteration to be established. The calculation is based on an assumption of the length of the free vortex sheets. Second, a viscous procedure based on a finite control volume scheme is used to solve the Navier-Stokes equations for turbulent flow by making used of the k-ε model. An algebraic pressure correction is incorporated in the calculation. The predictions from the two models are in reasonable agreement with experimental measurements.