|Department||Environmental and Applied Fluid Dynamics|
|Deadline||June 15, 2022|
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“A scientist studies what is, whereas an engineer creates what never was“, Théodore von Kármán
Duration of the postdoc: 4 years
Deadline: 15 June 2022
About the Research Topic
Industrial risks management is of primary importance in chemical plants. In particular, gas leakage coming from an explosion in a pressurized reservoir is highly concerning. The ejection of the pollutants at high velocity in the atmosphere would lead to a supersonic jet.
While literature on supersonic jets can be found, the effect of the atmospheric wind conditions on such dispersion is still unclear. The SHADE project (Supersonic Hot Atmospheric DispErsion) enters in the collaboration with the CEA Gramat research center. It aims to continue research efforts to characterize the supersonic jet dispersion under atmospheric wind conditions. During the project, an extensive experimental dataset will have to be provided and confronted with numerical simulations from the CEA. Optical measurement techniques will need to be developed and validated to measure the velocity and the concentration fields of the dispersion. To improve the understanding of the dispersion, measurements need to be conducted in the near field and far from the release point, in the self-similar region. The other main key challenge of the PhD will be to adapt the experimental setup and measurement techniques for a high temperature jet. In addition to the experimental technique’s development, the research project envisions to test the supersonic jet as submitted to an atmospheric boundary layer provided by a wind tunnel and to study unsteady effects of the jet.
The project can be divided into five main work packages. First, an extensive bibliographical review will have to be conducted on the supersonic jet dispersion and experimental methods to characterize such a flow. During this phase, the candidate will be guided by the expertise of VKI and will be taught advanced measurement techniques regularly used at the institute. The second work package consists in developing new experimental methods to characterize the dispersion. LS-PIV (Large Scale Particle Image Velocimetry) has been successfully applied to measure the velocity field. For the concentration, a technique based on the Mie Scattering was adapted and allowed to measure a concentration field, as observed in the image above, but a proper reference is needed as this technique provides the concentration field as compared to a reference value. Therefore, the idea is to use another technique, such as the Light Extinction spectroscopy, to give an absolute value of the reference concentration.
The third work package involves designing a new experimental setup to simulate the supersonic jet. The work will be conducted in tight collaboration with the drawing office and the technical team of the von Karman Institute. The measurements will be performed in the VKI Wind Engineering facility L-1B. The 2 m high, 3m wide, and 20 m long wind tunnel is used to simulate a wind condition similar in nature to the lower part of the atmospheric neutral boundary layer with a roughened floor allowing the growth of a turbulent layer. Special care is taken in the proper simulation of turbulence parameters, namely intensity of fluctuation and power spectra. Optimal similarity conditions are obtained in the scale range 1/250 to 1/350. Flow velocity can be varied between 2 and 50 m/s making it one of the most powerful facilities of this type as far as Reynolds simulation is concerned.
The fourth WP will be the experimental campaigns. The first experimental campaigns will focus only on the dispersion (concentration and velocity fields) for selected wind and jet conditions. Therefore, the effect of temperature will be investigated by heating the jet up to 300 Celcius before the release. The main challenge of the project comes from the large scale of the dispersion, the high temperature, and the unsteady behavior of the release. Results will be analyzed and compared with numerical simulations. Finally, the last work package consists of the dissemination of the results. Regular meetings with the CEA will be conducted to discuss the results. Conclusions will be drawn and published via peer-reviewed papers and international conferences to bring new insight into the supersonic release in the atmosphere.
VKI does strictly adhere to the ethical standards of the European Charter for Researchers and Code of Conduct for the Recruitment of Researchers
For further information, please contact Pr. Delphine Laboureur email@example.com.
How to apply
Applications must contain a CV, motivation letter, publication list, contact information of two referees, copy of the Degree and Master title. CV must clearly indicate the exact dates of (1) each position hold in the past, and (2) countries of residence in the last 5 years.
All the fields (including pdf files and references) should be filled in to allow you to confirm your application. Only full applications will be taken into account. Please do not use white spaces or special characters to name your files. If you have not received a confirmation email it means that you have not fulfilled all required fields.
Short-listed candidates are called for an interview with the search committee at the von Karman Institute. The selected candidate must comply with the internal procedures of the von Karman Institute before she or he can begin to work. The von Karman Institute reserves the right not to appoint a candidate if no suitable candidate is found.