Numerical investigation of the effects of turbulence intensity on dam-break flows

2012 ◽  
Vol 42 ◽  
pp. 176-187 ◽  
Author(s):  
Il-Ryong Park ◽  
Kwang-Soo Kim ◽  
Jin Kim ◽  
Suak-Ho Van
Keyword(s):  
Numerical Investigation ◽  
Turbulence Intensity ◽  
Dam Break

Numerical Investigation on Leading Edge of Film Cooling Blade with Different Turbulence and Blowing Ratios

2014 ◽  
Vol 1070-1072 ◽  
pp. 1731-1734
Author(s):  
Shao Hua Li ◽  
Ge Wu ◽  
Ling Zhang
Keyword(s):  
Temperature Field ◽  
Numerical Investigation ◽  
Turbulence Intensity ◽  
Film Cooling ◽  
Leading Edge ◽  
Cooling Efficiency ◽  
Simulated Temperature

In order to investigate the influence of cooling efficiency of leading edge of film cooling blade with different turbulence intensity and blowing ratios,which use method of N-S equation,various blowing ratios of 1.0、1.5 and 2.0,various turbulence intensity of 5%、12%、20% and 30%,it simulated temperature field in leading edge of film cooling blade.The results show: cooling efficiency decreased when blowing ratios is increased.When turbulence intensity is 5%、12% and 20%,it obtains maximum cooling efficiency blowing ratios of 1.0.When turbulence intensity is 30%,it obtains maximum cooling efficiency blowing ratios of 1.5. In blowing ratios of 1.0,cooling efficiency decreased when turbulence increased.But in blowing ratios of 1.5 and 2.0,cooling efficiency increased when turbulence increased.

scholarly journals Numerical investigation of stall characteristics for winglet blade of a horizontal axis wind turbine

2021 ◽  
Vol 321 ◽  
pp. 03004
Author(s):  
Shalini Verma ◽  
Akshoy Ranjan Paul ◽  
Anuj Jain ◽  
Firoz Alam
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Numerical Investigation ◽  
Turbulence Intensity ◽  
Geometric Modeling ◽  
Cfd Simulation ◽  
Lift Coefficient ◽  
Horizontal Axis ◽  
Renewable Energy Resources ◽  
Horizontal Axis Wind Turbine

Wind energy is one of the renewable energy resources which is clean and sustainable energy and the wind turbine is used for harnessing energy from the wind. The blades are the key components of a wind turbine to convert wind energy into rotational energy. Recently, wingtip devices are used in the blades of horizontal axis wind turbine (HAWT), which decreases the vortex and drag, while increases the lift and thereby improve the performance of the turbine. In the present study, a winglet is used at the tip of an NREL phase VI wind turbine blade. Solidworks, Pointwise, and Ansys-Fluent are used for geometric modeling, computational grid generation, and CFD simulation, respectively. The computational result obtained using SST k-ω turbulence modeling is well validated with the experimental data of NREL at 5 and 7 m/s of wind speeds. Numerical investigation of stall characteristics is carried out for wingleted blade at higher turbulence intensity (21% and 25%) and angle of attack (00 to 300 at 50 intervals) at 7 m/s wind speed. The result found that wingletd blade delay stall to 150 for both the cases of turbulence intensity. Increasing the turbulence intensity increases the lift coefficient at stall angle but drag coefficient also increases and thus a lower aerodynamic performance (CL/CD ratio = 13) is obtained. Wingleted blade improves the performance as the intensity of vortices is smaller compared to baseline blade

Numerical Investigation of Inlet Turbulence Intensity Effect on a Bluff-Body Stabilized Flame at Near Flame Blow-Off Conditions

2020 ◽  
Author(s):  
Amir Ali Montakhab ◽  
Benjamin Akih Kumgeh
Keyword(s):  
Boundary Conditions ◽  
Numerical Investigation ◽  
Turbulence Intensity ◽  
Bluff Body ◽  
Chemical Species ◽  
Simulation Method ◽  
Intensity Effect ◽  
Flame Instability ◽  
Eddy Simulation ◽  
Lean Conditions

Abstract This paper investigates the effects of the inlet turbulence intensity (ITI) on the dynamics of a bluff-body stabilized flame operating very close to its blow-off condition. This work is motivated by the understanding that more stringent regulations on combustion-generated emission have forced the industry to design combustion systems that operate at very fuel-lean conditions. Combustion at very lean conditions, however, induces flame instability that can ultimately lead to flame extinction. The dynamics of the flame at lean conditions can therefore be very sensitive to boundary conditions. Here, a numerical investigation is conducted using Large Eddy Simulation method to understand the flame sensitivity to inlet turbulence intensity. Combustion is accounted for through the transport of chemical species. The sensitivity to inlet turbulence is assessed by carrying out simulations in which the inlet turbulence is varied in increments of 5%. It is observed that while the inlet intensity of 5% causes blow-off, further increased to 10% preserves a healthy flame on account of greater heat release arising from greater and balanced entrainment of combustible mixtures into the flame zone just behind the bluff-body. This balanced stabilization is again lost as the inlet turbulence intensity is further increased to 15%. Since experimental data pertaining to the topic of this paper are rare, the reasonableness of the combination of models is first checked by validating Volvo propane bluff-body flame, whereby reasonable agreement is observed. This study will advance our understanding of the sensitivity of bluff-body flames to boundary conditions specifically to the inlet turbulent boundary condition at near critical blow-off flame conditions.

Numerical investigation of the gate motion effect on a dam break flow

2016 ◽  
Vol 21 (4) ◽  
pp. 579-591 ◽  
Author(s):  
Zhouteng Ye ◽  
Xizeng Zhao ◽  
Zhengzhi Deng
Keyword(s):  
Numerical Investigation ◽  
Dam Break ◽  
Motion Effect ◽  
Dam Break Flow

scholarly journals Numerical Simulation and Aerothermal Physics of Leading Edge Film Cooling

1998 ◽  
Author(s):  
A. Chernobrovkin ◽  
B. Lakshminarayana
Keyword(s):  
Numerical Simulation ◽  
Mach Number ◽  
Numerical Investigation ◽  
Turbulence Intensity ◽  
Film Cooling ◽  
Leading Edge ◽  
Length Scale ◽  
Cooling Effectiveness ◽  
Turbulence Length ◽  
Turbulence Length Scale

A viscous flow solver based on the Runge-Kutta scheme has been modified for the numerical investigation of the aerothermal field due to the leading edge film cooling at a compound angle. An existing code has been modified to incorporate multi-block capabilities. Good agreement with the measured data has been achieved. Results of the numerical investigation have been used to analyze the vortex structure associated with the coolant jet-freestream interaction to understand the contribution of different vortices on the cooling effectiveness and aerothermal losses. Two counter-rotating vortices generated by the interaction between the mainflow and the coolant jet have been found to have a major influence in decreasing the cooling efficiency through strong entrainment of the hot fluid. Numerical simulation was carried out to investigate the influence of the inlet Mach number, inlet turbulence intensity, and length scale on the aerothermal field due to the leading edge film cooling. Variation of the inlet Mach number leads to a minor modification of the cooling effectiveness, and this is predominantly caused by the modified pressure gradient. Increased turbulence intensity has profound effect on the cooling near the leading edge. Adiabatic effectiveness downstream of the second row of coolant holes is less sensitive to a change in turbulence intensity. Results of the numerical simulation indicate that the turbulence length scale has a significant effect on the accuracy of the numerical prediction of film cooling. Not only the inlet turbulence intensity but also the turbulence length scale should be accurately set to achieve a reliable numerical prediction of the heat and mass transfer due to film cooling.

Numerical investigation of the impact of a dam-break induced flood on a structure

2021 ◽  
Vol 223 ◽  
pp. 108669
Author(s):  
Ling Peng ◽  
Ting Zhang ◽  
Youtong Rong ◽  
Chunqi Hu ◽  
Ping Feng
Keyword(s):  
Numerical Investigation ◽  
Dam Break ◽  
The Impact
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