UNSTEADY RANS MODELING OF WATER-SPRAY SUPPRESSION FOR LARGE-SCALE COMPARTMENT POOL FIRES

2007 ◽  
Vol 17 (1) ◽  
pp. 1-45 ◽  
Author(s):  
Sam S. Yoon ◽  
Ho Young Kim ◽  
Paul E. DesJardin ◽  
John C. Hewson ◽  
Sheldon R. Tieszen ◽  
...  
Keyword(s):  
Large Scale ◽  
Water Spray ◽  
Pool Fires ◽  
Unsteady Rans ◽  
Rans Modeling

Unsteady RANS Simulation of Turbulent Flow and Heat Transfer in Ribbed Coolant Passages of Different Aspect Ratios

2004 ◽  
Author(s):  
A. K. Saha ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Rotation Number ◽  
Large Scale ◽  
Density Ratio ◽  
Navier Stokes ◽  
Flow Structures ◽  
Flow And Heat Transfer ◽  
Aspect Ratios ◽  
Unsteady Rans

The flow and heat transfer in ribbed coolant passages of aspect ratios (AR) of 1:1, 4:1, and 1:4 are numerically studied through the solution of the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations. The ribs are oriented normal to the flow and arranged in a staggered configuration on the leading and trailing surfaces. The URANS procedure can resolve large-scale bulk unsteadiness, and utilizes a two equation k-ε model for the turbulent stresses. Both Coriolis and centrifugal buoyancy effects are included in the simulations. The computations are carried out for a fixed Reynolds number of 25000 and density ratio of 0.13 while the Rotation number has been varied between 0.12–0.50. The average duct heat transfer is the highest for the 4:1 AR case. For this case, the secondary flow structures consist of multiple roll cells that direct flow both to the trailing and leading surfaces. The 1:4 AR duct shows flow reversal along the leading surface at high rotation numbers with multiple rolls in the secondary flow structures near the leading wall. For this AR, the potential for conduction-limited heat transfer along the leading surface is identified. At high rotation number, both the 1:1 and 4:1 AR cases exhibit loss of axial periodicity over one inter-rib module. The friction factor reveals an increase with the rotation number for all aspect ratio ducts, and shows a sudden jump in its value at a critical rotation number because of either loss of spatial periodicity or the onset of backflow.

Scrutiny of buffet mechanisms in transonic flow

2018 ◽  
Vol 28 (5) ◽  
pp. 1031-1046 ◽  
Author(s):  
Antonio Memmolo ◽  
Matteo Bernardini ◽  
Sergio Pirozzoli
Keyword(s):  
Boundary Layer ◽  
Transonic Flow ◽  
Acoustic Waves ◽  
Numerical Experiments ◽  
Large Scale ◽  
Pressure Side ◽  
Trailing Edge ◽  
Content Type ◽  
Unsteady Rans ◽  
Transonic Buffet

Purpose This paper aims to show results of numerical simulations of transonic flow around a supercritical airfoil at chord Reynolds number Rec = 3 × 106, with the aim of elucidating the mechanisms responsible for large-scale shock oscillations, namely, transonic buffet. Design/methodology/approach Unsteady Reynolds-averaged Navier–Stokes simulations and detached-eddy simulations provide a preliminary buffet map, while a high fidelity implicit large-eddy simulation with an upstream laminar boundary layer is used to ascertain the physical feasibility of the various buffet mechanisms. Numerical experiments with unsteady RANS highlight the role of waves travelling on pressure side in the buffet mechanism. Estimates of the propagation velocities of coherent disturbances and of acoustic waves are obtained, to check the validity of popular mechanisms based on acoustic feedback from the trailing edge. Findings Unsteady RANS numerical experiments demonstrate that the pressure side of the airfoil plays a marginal role in the buffet mechanism. Implicit LES data show that the only plausible self-sustaining mechanism involves waves scattered from the trailing edge and penetrating the sonic region from above the suction side shock. An interesting side result of this study is that buffet appears to be more intense in the case that the boundary layer state upstream of the shock is turbulent, rather than laminar. Originality/value The results of the study will be of interest to any researcher involved with transonic buffet.

Buoyant plumes of large-scale pool fires

1982 ◽  
Vol 19 (1) ◽  
pp. 905-912 ◽  
Author(s):  
Hsiang-Cheng Kung ◽  
Paraskevas Stavrianidis
Keyword(s):  
Large Scale ◽  
Pool Fires ◽  
Buoyant Plumes

Experimental study on the interaction of fine water spray with liquid pool fires

2001 ◽  
Vol 10 (4) ◽  
pp. 377-384 ◽  
Author(s):  
Guangxuan Liao ◽  
Jianghong Liu ◽  
Jun Qin ◽  
Bin Yao
Keyword(s):  
Experimental Study ◽  
Liquid Pool ◽  
Water Spray ◽  
Pool Fires

Behavior of luminous zones appearing on plumes of large-scale pool fires of kerosene

1999 ◽  
Vol 33 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Nobuhide Takahashi ◽  
Masataro Suzuki ◽  
Ritsu Dobashi ◽  
Toshisuke Hirano
Keyword(s):  
Large Scale ◽  
Pool Fires
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