UFR 1-07 Test Case
Unsteady Near-Field Plumes
Underlying Flow Regime 1-07
Test Case Study
Brief Description of the Study Test Case
- A summary of the boundary conditions is shown in Figure 8.
- A gas mixture mainly composed of helium is discharged through a circular orifice into ambient air.
- The gas is composed of 96.4% helium, 1.7% acetone and 1.9% oxygen by volume.
- The molecular weight of the gas released is 5.45 g/mol ±2.7%.
- The mixture is discharged at a temperature of THe = 11°C ±3°C and the air is at Tair = 13°C ±3°C.
- The circular plume source has diameter, D = 1 metre.
- The helium is discharged at a Reynolds-averaged velocity V0 = 0.325 m/s ±1.3% and a Favre-averaged velocity of approximately 0.339 m/s.
- The flow through the orifice is laminar.
- The ambient pressure is 80.9 kPa ±0.4 kPa.
- The measurements include:
- Time-history of vertical velocity at a point 0.5 m from the centreline and 0.5 m above the inlet, used to estimate the puffing frequency
- Measurements on a vertical plane through the plume from the plume source to a distance of one orifice diameter of:
- Reynolds-averaged and Favre-averaged mean axial and radial velocities
- Reynolds-averaged and Favre-averaged shear stresses, normal stresses and turbulent kinetic energy\footnote{Only velocities parallel
to a two{}-dimensional plane were recorded. The turbulent kinetic energy, \textit{k}, is calculated from the vertical and horizontal normal stresses ( $\overline{{\mathit{uu}}}$ and $\overline{{\mathit{ww}}}$ ) by assuming that the horizontal component is the same in the out{}-of{}-plane direction ( $\overline{{\mathit{vv}}}=\overline{{\mathit{ww}}}$ ), i.e. assuming that $k\approx \left(\overline{{\mathit{uu}}}+2\overline{{\mathit{ww}}}\right)/2$ .}
- Favre-averaged helium concentrations
- Movies of helium concentration and velocities
- Profiles of the mean and RMS velocities, and mean and RMS helium concentrations at six measurement positions (0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 m downstream of the plume source)
Item 1 is available in the O{\textquotesingle}Hern \textit{et al}. [4] paper, Items 2 and 3 can be obtained by contacting the authors of the study\footnote{\textmd{Dr. Tieszen}\textmd{ (srtiesz@sandia.gov) or Dr. O{\textquotesingle}Hern (tjohern@sa}\textmd{ndia.gov).}} and Item 4 is presented by \textmd{\textup{Chung \& Devaud }}\textmd{\textup{[39]}}.
Test Case Experiments
CFD Methods
Contributed by: Simon Gant — UK Health & Safety Laboratory
© copyright ERCOFTAC 2010