A month ago, Monday 23rd June 2000 (MNM Week 26), we reported the Annual Seminar and Summer Management Meeting of the EuroFlam consortium at Florence Italy on Wednesday 21st and Thursday 22nd June. Twelve Graduates/Visiting Investigators who presented their completed reports or progress reports attended the meeting.

This week, in this Volume 3, we are publishing the last series of abstracts of the presentations made at the Seminar.

Wavelet Cross­Correlation Analysis of Turbulent Mixing from Large­Eddie­Simulation
by Jacopo Bellazzini - ENEL

Abstract:
The complex interactions existing between turbulence and mixing in an isothermal bluff body stabilised flame configuration is investigated by mean of a wavelet cross­correlation analysis on Large Eddie Simulations. This combined approach allows to better point out typical features of non­stationary turbulent flows with mixing through the characterisation of the processes involved both in time and scales. The highly redundant information from a multiscale wavelet analysis of time series is reduced by mean of suitable selective procedures and quantities, in order to extract the main features correlated to an essentially intermittent dynamics. In particular, in this study, we analysed and compared the properties of two complementary wavelet local correlation coefficients which are able to well evidence peculiar and anomalous local events associated to vortex dynamics.

More precisely, given two signals f(t) and g(t), we refer to the so-called Wavelet Local Correlation Coefficient (WLCC, Buresti, Lombardi, 1999) defined as:

Development of a New Version of VisCFD
by Uyen Nguyen - ENEL

Abstract:
The forefront of the research and development activities at ENEL Production - Research is represented by experiments of numerical simulation making use of very powerful computers like CRAY T90. To have an effective comprehension of complex simulations, the use of sophisticated visualisation tools run on powerful workstations are required. A project was started in 1997 to develop tools for the direct manipulation of scientific visualisation models in virtual reality environments.

The first result was a prototype named VisCFD with interesting features based on a strong interaction between the user and the visualisation models. VisCFD was then developed porting the VisCFD prototype to C++ and integrating it with a new GUI package.

The objectives of the work at ENEL Research are concerned with the development and the optimisation of a new version of VisCFD. The first stage will involve the porting of VisCFD into the new software architecture (slice, bar and sphere widget, etc.). Presentation of VisCFD to the users, collection of desiderata and specifications document for the release will follow. Finally, the implementation of new features (stereo rendering, volume rendering, etc.) will be carried out.

Design procedure of large scale effervescent atomizers
by Nicola Bundschuh - ENEL

Abstract:
A single port effervescent atomizer formed like a slice of an existing twelve-port atomizer designed and studied by Sig. Ligasacchi is built and spray measurement with a twelfth of the mass flow rate of the full scale model is taken. Calculations of the flow inside the single port atomizer with the CFD-code "FLUENT" are performed to verify the two-phase distribution visualized with photos. The implemented two phase flow models are the "Volume of Flow Model" and the "Algebraic Slip Mixture Model". Further activities are to make calculations of the twelve-port atomizer and modify the geometry with inserts to reach a better mixing.

Appraisal of Particulate Sampling Systems for two Industrial Furnaces
by Christina M. Georgousopolou - UWC

Abstract:
This project is coupled in with ongoing studies, which have been the focus of previous EuroFlam projects, namely Carbon Black production from a Gas-Fired furnace, and the emission performance of a 2MW Oil-Fired furnace.

The project undertakes a preliminary study of a simple, low-cost system proposed for sampling and quantifying particulate production from exhaust streams of the aforementioned furnaces. The system was primary designed to be employed for sampling from the Carbon Black furnace, where the solid yield is particularly high (typically 5% carbon recovery). The same system has been employed to assess its applicability for use in sampling PM emissions from the exhaust of the Oil-Fired furnace stream, where sample concentrations are significantly lower.

It is concluded that the design is appropriate for use in determining Carbon Black yield (with associated gas analysis experiment), whereas the PM concentrations derived from the Oil-Fired furnace were considerably lower than anticipated (order of 1 mg/m3).

Further work is required to determine whether this exceptionally low concentration is due to the fuels characteristics combustion conditions, or a deficiency of the sampling system itself. The latter currently seems to be the most likely source.

Application of the Helmholtz model to bulk mode oscillations in a swirl burner
by V. M. Rodriguez Martinez - UWC

Abstract
Acoustic models previously used to interpret the resonant behaviour in a swirl burner have been based on the models employed by Helmholtz pulse combustors. Additional geometrical and fluid dynamic considerations have given rise to a novel interpretation of the model.

It was found that the exhaust pipe is not an integral part of the oscillating system as it will resonate without one. Therefore, air supply lines and the burner/chamber geometry constitute the system components that determine mode, amplitude and frequency of the oscillation. The pipe and other downstream confinements ensure a pressure balance between the inlet pipe work and the chamber that influences the mixing and reaction processes which take place for each pressure cycle.

The justification of the above mentioned theory accompanied by the results obtained from a set of LDA and pressure measurements taken at Cardiff University, is the content of this exposition.

 

Individual New Individual Members - Week 30: Contributed by Lois Brett EuroFlam Investigators in Business: Contributed by Gabriel Gallagher and Lois Brett Annual EuroFlam Seminar 2000, Abstracts - Vol 3: Contributed by Aristide Mbiock and Peter Roberts World Energy News: Contributed by Aristide Mbiock

 

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Edited: Peter Roberts
ISSN 1562-4781