Influence of music genre and composition on entertainment noise limits

Liquor licensing authorities across Australia typically require an entertainment noise test to be conducted before a venue can host amplified entertainment. The purpose of this test is to simulate live entertainment in order to determine the maximum permissible noise source limits allowed for the venue. In this paper, several disadvantages of the current method used for entertainment noise testing are identified and discussed. It was found that the choice of music can affect the resulting source noise level limits. An alternative approach has been suggested which involves playing band-limited pink noise across the 63 to 2kHz octave bands. A correction is then applied to determine the source noise level limits associated with different genres of music. The advantages of this method are that it reduces the time required to conduct the test, the nuisance caused to neighbouring premises is reduced and the variance in source noise level limits caused by different choice of test music is eliminated

Uncertainty Analysis of Conditions in the Test Section of the T4 Shock Tunnel

A method is presented for estimating the uncertainties in the flow conditions at the exit of the nozzle of the T4 shock tunnel in the Department of Mechanical Engineering at The University of Queensland. The method used to estimate the uncertainties is presented along with results for some test conditions. Four conditions are considered specifically - each for the Mach 5 nozzle with air as the test gas. The stagnation enthalpy for these conditions varies from 3 MJ/kg to 14 MJ/kg. The results indicate that typical uncertainties in static pressures, temperatures and densities are around +/- 10% while uncertainties in flow speed and Mach number are around +/- 5% and +/- 2% respectively

Dynamic Calibration of Force Balances

This report describes different techniques for the calibration of stress-wave force balances. A short introduction is presented on how deconvolution can be used to infer aerodynamic forces on models in impulse hypersonic wind tunnels along with the theory behind the different calibration techniques. Simulations of calibration tests and recovery of forces using the different calibration techniques are performed to show the accuracy with which impulse responses can be found and aerodynamic forces resolved. Bench tests for a single-component stress-wave force balance and experiments in the T4 shock tunnel using the same balance are used to demonstrate the suitability of different calibrations. It is shown that the impulse response derived from tests involving the cutting of a fine wire which suspends the model and force balance agrees very well with impulse responses derived from calibrations made using an impact hammer. However, some of the methods used for impact calibrations are very sensitive to noise on the measurement signals. Techniques for minimizing these effects and for dealing with the noise to reduce errors are also presented

Numerical Simulation of a Ludwieg-tube Fuel Delivery System for Scramjet Experiments in Shock Tunnels

The T4 shock tunnel at The University of Queensland is regularly used to perform supersonic combustion experiments. The fuel for the test model is supplied using a Ludwieg-tube delivery system. A combination of theoretical modelling and calibration tests is used to determine the mass flow-rate of fuel for given Ludwieg tube initials conditions and the measured pressure in the plenum chamber that supplies the fuel to the model. The theoretical model used in the calibration procedure is presented. The goal of this project is to check the suitability of the modelling assumptions by simulating the complete Ludwieg-tube system using the one-dimensional Lagrangian computer code, L1d. Simulation of the fuel delivery system is done separately for viscous and inviscid flow with conditions replicating those used in supersonic combustion tests in T4. The steady plenum pressures from the simulations of inviscid and viscous flow are, on average, within ±7% and ±4%, respectively, of the values measured experimentally. Further, the fuel mass flow-rates obtained from viscous simulations are, on average, within ±13% of the experimental values

A test facility for hypervelocity rarefied flows

This paper describes a rarefied hypervelocity test facility producing gas speeds greater than 7 km/s. The X1 expansion tube at the University of Queensland has been used to produce nitrogen flows at 8.9 and 9.5 km/s with test flow durations of 50 and 40 microsecond­s respectively. Rarefied flow is indicated by values of the freestream breakdown parameter > 0.1 (Cheng's rarefaction parameter < 10) and freestream Knudsen numbers up to 0.038, based on a model size of 9 mm. To achieve this, the test gas is expanded from the end of the acceleration tube into a dump tank. Nominal conditions in the expansion are derived from CFD predictions. Measured bar gauge (Pitot) pressures show that the flow is radially uniform when the Pitot pressure has decreased by a factor ten. The measured bar gauge pressures are an increasing fraction of the expected Pitot pressure as the rarefaction parameters increase

Visualization Of Supersonic Flows In Shock Tunnels, Using The Background Oriented Schlieren Technique

Visualisation of supersonic compressible flows using the Background Oriented Schlieren (BOS) technique is presented. Results from experiments carried out in a reflected shock tunnel with models of a 20-degree semi-vertex angle circular cone and a re-entry body in the test section are presented. This technique uses a simple optical set-up consisting of a structured background pattern, an electronic camera with a high shutter speed and a high intensity light source. Tests were conducted with a Mach 4 conical nozzle, with nozzle supply pressure of 2 MPa and nozzle supply temperature of 2000 K respectively. The images captured during the test were compared using PIV style image processing code. The intensity of light at each point in the processed image was proportional to the density at that point. Qualitative visualization of shock shapes, with images clearly indicating regions of subsonic and supersonic flows was achieved. For the cone, the shock angle measured from the BOS image agreed with theoretical calculations to within 0.5 degrees. Shock standoff distances could be measured from the BOS image for the re-entry body

Labour efficiency on-farm

End of project reportImprovements in milking efficiency have a greater influence than any other aspect of the dairy farmers work on overall farm labour inputs (Whipp, 1992). In order to facilitate the examination of milking process labour inputs, the milking process may be divided into the following three components: herding pre and post milking (transfer of cows to and from the milking parlour); milking (milking tasks / work routines within the parlour); and washing (washing of milking machine and yard). Meanwhile, within milking specifically, the number of cows milked per operator per hour is the best measure of both the performance of the operator and the milking installation (Clough, 1978). This is affected by the following three factors: the milking times of the cows, the number and arrangement of the milking units, and the operator’s work routine (Whipp, 1992). The addition of extra milking units will only increase milking performance if the operator has idle time during milking (Hansen, 1999)

Investigation of Weak Shock-Shock and Shock-Expansion Intersection in the Presence of a Turbulent Boundary Layer

An investigation of intersecting shock-shock and shock-expansion interactions with a turbulent boundary layer is reported. The form of these interactions is interpreted from experimental results at Mach 1.85. It is found that intersecting shock interactions can produce a given overall pressure rise with less likelihood of separation than an equivalent strength single shock interaction. A simple theory to predict limiting streamline deflection angles is extended to boundary layer interactions with multiple merging and intersecting shock wave and expansion fan configurations and shows reasonable agreement with experiments. The possibility that intersecting wave interactions can lead to boundary layer separation is discussed

New calibration technique for multiple-component stress wave force balances

Force measurement in hypervelocity expansion tubes is not possible using conventional techniques. The stress wave force balance technique can be applied in expansion tubes to measure forces despite the short test times involved. This paper presents a new calibration technique for multiple-component stress wave force balances where an impulse response created using a load distribution is required and no orthogonal surfaces on the model exist.. This new technique relies on the tensorial superposition of single-component impulse responses analogous to the vectorial superposition of the calibration loads. The example presented here is that of a scale model of the Mars Pathfinder, but the technique is applicable to any geometry and may be useful for cases where orthogonal loads cannot be applied

Numerical investigations of flow and energy fields near a thermoacoustic couple

The flow field and the energy transport near thermoacoustic couples are simulated using a 2D full Navier-Stokes solver. The thermoacoustic couple plate is maintained at a constant temperature; plate lengths, which are short and long compared with the particle displacement lengths of the acoustic standing waves, are tested. Also investigated are the effects of plate spacing and the amplitude of the standing wave. Results are examined in the form of energy vectors, particle paths, and overall entropy generation rates. These show that a net heat-pumping effect appears only near the edges of thermoacoustic couple plates, within about a particle displacement distance from the ends. A heat-pumping effect can be seen even on the shortest plates tested when the plate spacing exceeds the thermal penetration depth. It is observed that energy dissipation near the plate increases quadratically as the plate spacing is reduced. The results also indicate that there may be a larger scale vortical motion outside the plates which disappears as the plate spacing is reduced. (C) 2002 Acoustical Society of America