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Item Metadata only Near field determination of the complex radiation efficiency and acoustic intensity distribution for a resonantly vibrating surface(Elsevier, 1979) Hansen, C.H.; Bies, D.A.An experimental procedure is described which allows both the resistive and reactive parts of the acoustic radiation efficiency of a resonantly vibrating surface to be determined from measurements in the acoustic near field. In addition, the procedure allows the precise quantitative location on the vibrating surfaces of acoustic sources which radiate energy to the far field. The method described here allows far greater detailed investigation of an acoustically radiating surface than is possible with alternative experimental procedures described in the literature.Item Metadata only Measurements of the radiation impedance presented to a source in a reverberant room containing a rotating diffuser(American Institute of Physics, 1979) Bies, D.A.; Hansen, C.H.Abstract not availableItem Metadata only Near field measurement of the complex radiation impedance presented to a vibrating plate in a reverberant room containing a rotating diffuser(Academic Press, 1980) Hansen, C.H.; Bies, D.A.The radiation impedance presented by the field of a reverberant room to a rectangular plate mounted in a large baffle and vibrating in its fundamental simply supported edge mode is experimentally investigated. It is shown that a large diffuser rotating at 30 rpm causes large variations in both the real and imaginary parts of the radiation impedance but the average values agree very well with values obtained in the free field of an anechoic room. The real part of the radiation impedance is in good agreement with theoretical prediction. The experimental method makes use of a time average hologram of the mode stored in computer memory, a single point acceleration measurement on the plate, and a surface pressure scan. The method allows investigation of side band frequencies generated by the plate in the presence of the rotating diffuser. It is shown that these side band frequencies contain negligible energy and that they are the result of the cyclic amplitude modulation of the power radiated by the plate.Item Metadata only Flow resistance information for acoustical design(Applied Science Publishers, 1980) Bies, D.A.; Hansen, C.H.The measurement and use of flow resistance information for the calculation of the acoustical properties of porous materials has been examined. It is demonstrated that flow resistance information provides a description of a porous material which is sufficient to characterise its acoustical performance for all common applications. Design charts are presented which facilitate the use of flow resistance information for the three most common applications: (1) the control of the reverberant sound field in an enclosure, (2) the improvement of the transmission loss through pipe wrappings and enclosure walls and (3) the attenuation of sound propagating in ducts. Measured values of flow resistance for fibrous and foamed products available in Australia are presented. Information is also presented for estimating the flow resistance of fibrous products of generally uniform fibre diameter. Alternatively, a means for the measurement of flow resistance is described.Item Metadata only Mixing enhancement by a self-exciting, asymmetric precessing flow-field(Elsevier Press, 1992) Nathan, G.; Luxton, R.Item Metadata only Reduced NOₓ emissions and enhanced large scale turbulence from a precessing jet burner(Elsevier, 1992) Nathan, G.; Luxton, R.; Smart, J.The performance characteristics of a Precessing Jet (PJ) burner, developed at the University of Adelaide, have been investigated in Furnace No. 1 of the International Flame Research Foundation firing natural gas with air pre-heated to 320°C. Results showed that the PJ burner, operating without air swirl, fuel staging or FGR, produces NOₓ emissions of about 57 ppm (dry, 3% O₂) which is comparable to the performance of a swirled flame operated at optimised conditions with either flue gas recirculation, FGR, or fuel staging. The emissions are significantly lower than the 134 ppm measured for the base-line swirl burner, but greater than the 37 ppm measured for the swirl burner operated with both FGR and fuel staging. The flame was investigated by means of in-flame measurement of temperature and species concentration using suction probes and by laser sheet visualisation and subsequently derived probability density functions of jet fluid concentration. These techniques show that the mixing and combustion processes are dominated by the presence of large scale structures. It is anticipated that a more complete understanding of the interaction between the large scale turbulence and the combustion process will lead to further improvements in the performance of the burner.Item Metadata only A low NOₓ gas burner with a radiant flame(Springer, 1993) Nathan, G.; Luxton, R.A Precessing Jet (PJ) burner has been developed which enhances large scale turbulence by means of a naturally occurring fluid-mechanical phenomenon. A highly stable gas flame is produced without air swirl, quarl or a bluff body stabiliser. The resulting natural gas flame is lower in temperature and is more luminous than flames from many conventional burners so that it reduces NO x emissions while achieving almost total burnout of combustibles. The high luminosity indicates potential for increased fuel utilisation efficiency in process industries where radiation heat transfer is important. For one configuration of the PJ burner firing natural gas in an 18MW industrial cement kiln, NO x emissions are shown to be reduced by 75% with a simultaneous reduction in CO when compared with the original turbulent jet burner. Photographs of these flames show that the PJ burner produces a more rapidly spreading and more luminous flame. For another configuration, firing natural gas in a 25kW laboratory furnace, the radiation spectra of the flame produced by the PJ burner are compared with a high quality commercial swirl burner. The mean radiation intensity produced by the PJ burner is some twenty times that of the commercial burner in the visible spectrum and the normalised fluctuating intensity is about 50%, some five times that of the commercial burner in the visible range. Good potential for flame detectability is therefore apparent. Mean intensity is shown to increase by a factor of three with the addition of swirl to the air.Item Metadata only Current research in active control of noise(Auburn University, 1994) Hansen, C.Item Metadata only The effect of residual stresses and weld geometry on the improvement of fatigue life(Elsevier, 1995) Nguyen, T. Ninh; Wahab, Muhammad AbdulItem Metadata only Study of a deterministic model in the theory of contagious disease(Wiley & Sons, 1995) Caldwell, James; Ram, Yitshak M.Item Metadata only Active control of vibration using a neural network(Institute of Electrical and Electronics Engineers, 1995) Snyder, Scott D.; Tanaka, NobuoItem Metadata only The final report on the improvement of the air conditioning system in CAPITA building(1995) Petrovic, V. M.; Luxton, R. E.Item Metadata only Refrigeration plant design(1995) Petrovic, V. M.; Luxton, R. E.Item Metadata only Burra: Copper, Green and Gold(Institution of Engineers Australia (SA Division), 1995) Pickles, J. M.; Orr, H. G.; Kemp, D. C.; Stewien, C. R.; Bock, R. J.; School of Mechanical EngineeringItem Metadata only Mathematical modelling of the internal bending moment at the top roll contact in multipass four-roll thin plate bending(Elsevier, 1995) Hua, Sansome; Baines, KeithItem Metadata only Reduction of radiated sound by use of actively controlled perforated panels(Elsevier, 1995) Burgemeister, K.; Hansen, C.Item Open Access Joint statistics between temperature and its dissipation rate components in a round jet(American Institute of Physics, 1995) Mi, Jianchun; Antonia, R. A.; Anselmet, F.Item Metadata only Thermal characteristics of turbulent vortices in the wake of a circular cylinder(Springer, 1995) Mi, Jianchun; Antonia, R. A.; School of Mechanical EngineeringItem Metadata only Testing of ENVIRON induction units with rockwool and perforated panels in use with multi lobe nozzles and profiled side wall(1995) Petrovic, V. M.; Luxton, R. E.Item Metadata only On mixing cement and the hot end of aerodynamics(Interline Publishing, 1995) Luxton, R. E.; School of Mechanical Engineering