Thermal performance analysis of plate fin arrays with hexagonal perforations under turbulent flow regime

2019 ◽  
Author(s):  
Imtiaz Taimoor ◽  
Md Lutfor Rahman ◽  
Nazneen Sultana Aankhy ◽  
Muzahid Bin Khalid
Keyword(s):  
Performance Analysis ◽  
Turbulent Flow ◽  
Flow Regime ◽  
Thermal Performance ◽  
Turbulent Flow Regime

Thermal Performance of Sensible Energy Storage Module Consisting of a Cementitious Matrix: The Effect of Operating Conditions

2020 ◽  
Author(s):  
Justin Caspar ◽  
Julio Bravo ◽  
Shuoyu Wang ◽  
Ahmed Abdulridha ◽  
Sudhakar Neti ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Energy Storage ◽  
Turbulent Flow ◽  
Flow Regime ◽  
Thermal Performance ◽  
Operating Conditions ◽  
Initial Time ◽  
Time Rate ◽  
Turbulent Flow Regime

Abstract The fluid flow and heat transfer inside a concrete thermal energy storage module is simulated for various heat transfer fluid flow rates and inlet temperatures. The storage performance of the module is characterized based on the volume-averaged temperature and normalized energy distribution through the block versus time. In the turbulent flow regime, induced mixing in the pipe strongly enhanced the performance of the module compared to the laminar regime. The block was able to fully charge and discharge in a turbulent flow regime, whereas that behavior was not present in the laminar flow regime. Varying the heat transfer temperature had an effect on the time rate of change of temperature as well as the charge times. As the thermal gradient increased, the initial time rate of temperature in the block increased as well as the charge time. Since the block has higher theoretical energy at a larger gradient, power over a longer duration is necessary to reach a saturation point. By characterizing the thermal performance of the module, the effect of material properties and operational parameters can be studied in order to design a module that can meet the needs of a power generation plant.

Loss Characteristics of Orifices and Nozzles

1978 ◽  
Vol 100 (3) ◽  
pp. 299-307 ◽  
Author(s):  
S. H. Alvi ◽  
K. Sridharan ◽  
N. S. Lakshmana Rao
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Flow Regime ◽  
Discharge Coefficient ◽  
Critical Reynolds Number ◽  
Reynolds Numbers ◽  
Center Line ◽  
Laminar Regime ◽  
Variation Of Parameters ◽  
Turbulent Flow Regime

Loss characteristics of sharp-edged orifices, quadrant-edged orifices for varying edge radii, and nozzles are studied for Reynolds numbers less than 10,000 for β ratios from 0.2 to 0.8. The results may be reliably extrapolated to higher Reynolds numbers. Presentation of losses as a percentage of meter pressure differential shows that the flow can be identified into fully laminar regime, critical Reynolds number regime, relaminarization regime, and turbulent flow regime. An integrated picture of variation of parameters such as discharge coefficient, loss coefficient, settling length, pressure recovery length, and center line velocity confirms this classification.

Investigation of Flow Dynamics Over Transitional-Type Microcavity

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Paulius Vilkinis ◽  
Nerijus Pedišius ◽  
Mantas Valantinavičius
Keyword(s):  
Turbulent Flow ◽  
Flow Regime ◽  
Recirculation Zone ◽  
Transitional Flow ◽  
Navier Stokes ◽  
Flow Topology ◽  
Rans Equations ◽  
Recirculation Flow ◽  
Turbulent Flow Regime ◽  
Transitional Type

Flow over a transitional-type cavity in microchannels is studied using a microparticle image velocimetry system (μPIV) and commercially available computational fluid dynamics (CFD) software in laminar, transitional, and turbulent flow regimes. According to experimental results, in the transitional-type cavity (L/h1 = 10) and under laminar flow in the channel, the recirculation zone behind the backward-facing step stretches linearly with ReDh until the reattachment point reaches the middle of the cavity at xr/L = (0.5 to 0.6). With further increase in ReDh, the forward-facing step lifts the reattaching flow from the bottom of the cavity and stagnant recirculation flow fills the entire space of the cavity. Flow reattachment to the bottom of the cavity is again observed only after transition to the turbulent flow regime in the channel. Reynolds-averaged Navier–Stokes (RANS) equations and large eddy simulation (LES) results revealed changes in vortex topology, with the flow regime changing from laminar to turbulent. During the turbulent flow regime in the recirculation zone, periodically recurring vortex systems are formed. Experimental and computational results have a good qualitative agreement regarding the changes in the flow topology. However, the results of numerical simulations based on RANS equations and the Reynolds-stress-baseline turbulence model (RSM-BSL), show that computed reattachment length values overestimate the experimentally obtained values. The RSM-BSL model underestimates the turbulent kinetic energy intensity, generated by flow separation phenomena, on the stage of transitional flow regime.

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