This thesis is concerned with the airborne noise reduction of agricultural tractor cabs. The characteristics of the noise radiated from a non-cab-equipped tractor have been evaluated and used in conjunction with the classical theories of airborne sound transmission loss to predict the airborne noise reductions of tractor cabs. An experimental cab has beep constructed and used to evaluate these predictions. The theoretical and experimental airborne noise reductions do not show a good agreement. This has been shown to be due to two ressons. Firstly, there are anomalies in the classical airborne sound transmission loss theory whereby the theoretical and experimental sound transmission loss spectra do not show good agreement. Secondly, one-dimensional standing wave resonances in the cab cavity have been shown to give rise to an irregular plateau in the experimental airborne noise reduction spectra. Anomalies have been shown to exist between airborne sound transmission loss theory and reverberant room transmission loss measurements. These have arisen because the theory has not hitherto considered panel flexure. Modifications have been introduced which take account of panel flexure and these show that the dependence of classical theory on the angle of incident excitation is false and angular dependence occurs on the transmitted side of the panel, giving rise to a coincidence effect on the transmitted side which is independent of the angle of incidence. These modifications give rise to complete qualitative explanation of the shape of empirical airborne sound transmission loss spectra. Quantitative modifications have not been introduced because of lack of information regarding the angular nature of the transmitted waves.

No description available.

The Climatic Wind Tunnel (CWT) is a facility used by the motor industry to test vehicles under climatic extremes without the need for expensive overseas test programs. This work focuses on the application of computer simulation to the Heating Ventilation and Air Conditioning (HVAC) plant that makes up a CWT facility. The objective being to reduce its operational costs through the identification of energy saving operational strategies. When in operation the CWT has a peak power consumption of 3MW. The implementation of any measures that would reduce this peak load would give rise to considerable savings in the operating costs of the facility. Computer simulation is an accepted technique for the study of systems operating under varying load conditions. Simulation allows rapid analysis of different strategies for operating plant and the effectiveness of achieving the desired effect without compromising the buildings performance. Models for the components of the CWT have been developed and coded in Neutral Model Format. These models have then been linked together in a modular simulation environment to give a model of the complete plant. The CWT plant naturally decomposesin to four major subsystems these being the test chamber, the soakroom, air make-up and refrigeration system. Models of all the primary and secondary HVAC plant are described as is how they constitute the systems that make up the CWT. Validation tests for individual components as well as for the systems have been carried out. To illustrate the potential of the application of computer simulation into finding improved modes of operation that would reduce the energy consumption of the facility, four studies have been carried out. The studies involve the possibility of scheduling the operation of condenser fans as a function of refrigeration load and outside ambient temperature, methods for the pre-test conditioning of a vehicle, a reduction in the secondary refrigerant flow temperature and an increase in the thickness of the insulated panels from which the facility is constructed. The studies carried out showed that there was potential for moderate energy savings to be made in the operation of the facility and that extended simulation runs would allow for the in-depth assessment of a large range of possible modes of plant operation in order to identify the areas where the greatest savings are possible.

The work presented in this thesis attempts to provide a deeper understanding of the physical phenomena associated with the dynamic stall process on finite wing planforms. The work involves the analysis of data from the Glasgow University unsteady aerodynamics database that has been built up over a number of years through contributions from a range of researchers. Analysis focuses on two finite wing models; one a rectangular wing of aspect ratio three and the other with the same overall dimensions but with 60o swept tips. However, as most research to date has focused on nominally two-dimensional data, the results are referenced to measurements made on a nominally two-dimensional NACA 0015 aerofoil model. This is appropriate as this aerofoil was used as the wing section of both of the three-dimensional wing models. Flow visualisation images collected in a previous study also provide valuable information to supplement the pressure analysis. It is shown that, although the flow at the mid span sections of the finite wings exhibit many of the features of the two-dimensional case, there are some significant differences. In particular, the three-dimensional flow is dominated by the downwash from the wing tips. This causes the normal force response during pitching to lag the static normal force curve. This is in complete contrast to the two-dimensional case where the shed vorticity induces the opposite effect. The downwash also influences the incidence of lift stall but it does so in a manner that is dependent on the reduced pitch rate. Despite these effects, it is established that the flow behaviour in the mid-span region is almost two-dimensional prior to vortex inception. This provides an opportunity to examine the relationship between the generation of vorticity, or vorticity flux, in the leading edge region and the origins of the dynamic stall vortex at specific span locations in location. The vorticity flux distributions around the leading edges of the nominally two-dimensional NACA 0015 aerofoil and the two finite wings are then examined for pitching cases. On this basis a link is established between the peak vorticity flux and the dynamic stall vortex formation. This is confirmed by comparison of the vorticity flux measurements with a previous dynamic stall vortex detection method. The two methods are shown to five almost identical results in situations where the flow may be considered nominally two-dimensional. This suggests that monitoring vorticity flux may provide a practical method of dynamic stall vortex detection. In regions of the finite wings that exhibit strong three-dimensional flow effects, i.e. away from the mid-span, the peak vorticity flux is achieved after the dynamic stall vortex forms. This suggests that vortex formation is triggered by interference from adjacent sections of the wing. To examine this possibility, the vorticity flux is compared to a criterion used to detect the initial instability of the boundary layer at the leading edge. It is shown that the relationship between this criterion and the peak vorticity flux is the same along the span of the wing. This is a significant result as it demonstrates that, although the leading edge response determines the incidence of vortex onset near the mid-span, the formation of the vortex on sections of the wing closer to the tips occurs before the leading edge becomes critical. The implications of this for dynamic stall modelling of two-dimensional dynamic stall predictors with lifting line formulations will not capture this effect.

Non-linear unsteady aerodynamic effects present major modelling difficulties in the analysis of aeroelastic response and in the subsequent design of appropriate controllers. As the direct use of the basic fluid mechanic equations is still not practical for aeroelastic applications, approximate models of the non-linear unsteady aerodynamic response are required. A rigorous mathematical framework, that can account for the complex non-linearities and time-history effects of the unsteady aerodynamic response, is provided by the use of functional representations. A recent development, based on functional approximation theory, has provided a new functional form; namely, multi-layer functionals. Moreover, the multi-layer functional representation for time-invariant, infinite memory systems is shown to be realisable in terms of temporal neural networks. In this work, a multi-layer functional representation of non-linear motion-induced unsteady aerodynamic response is presented. A discrete-time, finite memory temporal neural network, in the form of a finite impulse response (FIR) neural network, is used as a practical realisation of a multi-layer functional. This model form permits the identification of parametric input-output models of the non-linear motion-induced unsteady aerodynamic response. Identification of an appropriate FIR neural network model is facilitated by means of a supervised training process using multiple sets of motion-induced unsteady aerodynamic response. The training process is based on a conventional genetic algorithm to optimise the FIR neural network architecture, and is combined with a simplification of the simulated annealing algorithm to update weight and bias values.

Trailing edge flaps may provide a mechanism for alleviating retreating blade stall. In the present investigation numerical simulations were conducted involving a NACA 0015 aerofoil section fitted with a plain trailing edge (TE) flap. All simulations were conducted using DIVEX, a tool being developed at the University of Glasgow, Department of Aerospace Engineering. In summary, the code uses a surface shedding discrete vortex method (DVM) for the simulation of 2-D incompressible flows around pitching aerofoils. The aero-foil is oscillating in pitch about its quarter chord axis and the clap undergoes negative pitch inputs, i.e. upward. An interesting feature appears to be that the cause of the severe nose down pitching movement introduced during dynamic stall is due to the cortical pair of the DSV and TEV where it is shown that the former feeds the latte in the case of the clean aerofoil for the range of reduced frequencies varying between k = 0.128 and k = 0.180. This fact suggests that manipulation of the vorticity in the vicinity of the trailing edge may be a mechanism for modification of the dynamic stall vortex (DSV) trajectory. This was found to relieve the aerofoil from severe pitching moment undershoot occurring during dynamic stall under appropriately phased flap actuations. Results obtained so far encourage the employment of a flap with fairly small size, 15% of the aerofoil chord. A parametric study is described which identifies the proper aerodynamic and actuation parameters for the current problem. In addition a simple open loop control scheme is developed based purely on rotor and flap related quantities.

Here both S-shaped and singly curved (here classified as S-shaped) duct diffusers for intakes in aeronautical propulsion systems are studied. The results are applicable in other situations where similar ducts occur; for example on V/STOL aircraft employing re-direction of thrust, intercomponent ducting in high bypass ratio engines, etc. An open circuit static test rig, capable of mass flow rates of 5 kg/s, and three-dimensional instrumentation were established. Flow measurements were made in S-shaped intake duct diffusers for rear mounted gas turbine engines in both aircraft and air-breathing missiles. These designs are intended for ventral type inlet installation. These ducts possess cross-sectional shape transitions, from oblate to circular, with area increase and annular ducts at the engine face. The work was aimed at both fundamental understanding of the flows and at establishing test data for the prediction methods. Tests were performed at throat Mach numbers of nominally 0.15 and 0.6 and in the unit Reynolds number range of 3x10_6/m - 2x10_7/m for three different ducts each having different upstream bends but common downstream bends. Detailed boundary layer surveys were made to establish plane of symmetry growth of the viscous region and the extent of three-dimensionality away from the plane of symmetry. Data are presented in the form of velocity profiles, streamwise and cross-flow, integral thicknesses and surface pressure fields. Engine face distortion is assessed from full outlet flow surveys. Flow visualization was recorded using surface oil flow techniques. Evidence is presented of a trend towards three-dimensional separation as the upstream bend increases in severity. For the most extreme case large regions of complex three-dimensional separated flow occur and topological analysis of the recorded surface oil flow pattern allows reconstruction of the separating flow. Clear correlations are established between flow visualization results and flow measurements yielding better understanding. Finally, results were compared with a three-dimensional compressible prediction method.

The classification of vehicle types and their attributes for various traffic modelling exercises is a common occurrence. The increasing use of microsimulation packages, which are based on modelling individual vehicles through the road network, points to the importance of having proper vehicle attributes specified in order to achieve the modelling results that match real-life conditions. / The use of a customised vehicle fleet instead of the default types that are usually built into microsimulation software will allow more accurate estimation of traffic performance indicators, such as speeds, travel times, capacity, fuel consumption etc. Most notably the accurate classification of vehicles is essential for reliable vehicle emissions modelling to occur, since the type and fuel used by vehicles has a significant effect on their emissions performance. To this end there are a number of databases that can be used for vehicle classification, these include but are not limited to: Australian Bureau of Statistics Motor Vehicle Census Data; Austroads Vehicle Classifications; Fleet composition models produced by Bureau of Transport Economics. / This thesis describes the development of the customised vehicle fleet to be used in Paramics microsimulation modelling package by Quadstone in the UK. Vehicle fleet profiles were developed for South Australian urban and rural conditions based on Australian Bureau of Statistics Motor Vehicle Census data and supplemented with other sources of vehicle kinematics and physical characteristics. / Thesis (MEng(TransportSystemsEng))--University of South Australia, 2005

Thesis (PhD)--University of South Australia, 1997

The classification of vehicle types and their attributes for various traffic modelling exercises is a common occurrence. The increasing use of microsimulation packages, which are based on modelling individual vehicles through the road network, points to the importance of having proper vehicle attributes specified in order to achieve the modelling results that match real-life conditions. / The use of a customised vehicle fleet instead of the default types that are usually built into microsimulation software will allow more accurate estimation of traffic performance indicators, such as speeds, travel times, capacity, fuel consumption etc. Most notably the accurate classification of vehicles is essential for reliable vehicle emissions modelling to occur, since the type and fuel used by vehicles has a significant effect on their emissions performance. To this end there are a number of databases that can be used for vehicle classification, these include but are not limited to: Australian Bureau of Statistics Motor Vehicle Census Data; Austroads Vehicle Classifications; Fleet composition models produced by Bureau of Transport Economics. / This thesis describes the development of the customised vehicle fleet to be used in Paramics microsimulation modelling package by Quadstone in the UK. Vehicle fleet profiles were developed for South Australian urban and rural conditions based on Australian Bureau of Statistics Motor Vehicle Census data and supplemented with other sources of vehicle kinematics and physical characteristics. / Thesis (MEng(TransportSystemsEng))--University of South Australia, 2005