Comparative thermal hydraulic performance analysis on helical screw insert in tube with different number of strips in transition flow regime

2020 ◽  
Vol 57 (1) ◽  
pp. 77-91
Author(s):  
Shashank Ranjan Chaurasia ◽  
R. M. Sarviya
Keyword(s):  
Performance Analysis ◽  
Flow Regime ◽  
Hydraulic Performance ◽  
Transition Flow ◽  
Transition Flow Regime

Thermal-Hydraulic Performance Analysis of Fluid Flow in Tube With Helical Screw Inserts in Transition Flow

2020 ◽  
Author(s):  
Shashank Ranjan Chaurasia ◽  
R. M. Sarviya
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Performance Analysis ◽  
Hydraulic Performance ◽  
Transition Flow ◽  
Maximum Enhancement ◽  
Transition Flow Regime ◽  
Twist Ratio ◽  
Single Strip

Abstract An experimental analysis is arranged to evaluate thermal hydraulic performance analysis on fluid flow in helical screw inserts in tube with number of strips and different twist ratios in Transition flow regime. Single strip insert is also compared with double strip inserts of helical screw inserts with three values of twist ratios. Heat transfer enhancement is achieved with fluid flow in double strip as compared to single strip helical screw insert at decreases values of twist ratios and increases values of Reynolds number (Re). Maximum enhancement in the value of Nusselt number is achieved with double strip inserts at low value of twist ratio and Reynolds number as compared to Single strip inserts. Common correlations of Nusselt number and friction factor are generated. Thermal performance factor (TPF) is achieved maximum values with double strip insert at all flow rates at 2.5 of twist ratio than single strip inserts. Double strip inserts show suitability of helical screw insert in heat exchangers to compact the size of thermal applications.

scholarly journals A Comparison and Unification of Ellipsoidal Statistical and Shakhov BGK Models

2015 ◽  
Vol 7 (2) ◽  
pp. 245-266 ◽  
Author(s):  
Songze Chen ◽  
Kun Xu ◽  
Qingdong Cai
Keyword(s):  
Kinetic Model ◽  
Flow Regime ◽  
Free Parameter ◽  
Numerical Solutions ◽  
Test Cases ◽  
Transition Flow ◽  
New Model ◽  
Transition Flow Regime ◽  
Generalized Kinetic Model ◽  
S Model

AbstractThe Ellipsoidal Statistical model (ES-model) and the Shakhov model (Smodel) were constructed to correct the Prandtl number of the original BGK model through the modification of stress and heat flux. With the introduction of a new parameter to combine the ES-model and S-model, a generalized kinetic model can be developed. This new model can give the correct Navier-Stokes equations in the continuum flow regime. Through the adjustment of the new parameter, it provides abundant dynamic effect beyond the ES-model and S-model. Changing the free parameter, the physical performance of the new model has been tested numerically. The unified gas kinetic scheme (UGKS) is employed for the study of the new model. In transition flow regime, many physical problems, i.e., the shock structure and micro-flows, have been studied using the generalized model. With a careful choice of the free parameter, good results can be achieved for most test cases. Due to the property of the Boltzmann collision integral, the new parameter in the generalized kinetic model cannot be fully determined. It depends on the specific problem. Generally speaking, the Smodel predicts more accurate numerical solutions in most test cases presented in this paper than the ES-model, while ES-model performs better in the cases where the flow is mostly driven by temperature gradient, such as a channel flow with large boundary temperature variation at high Knudsen number.

Fibrous Filter Efficiency and Pressure Drop in the Viscous-Inertial Transition Flow Regime

2012 ◽  
Vol 46 (2) ◽  
pp. 138-147 ◽  
Author(s):  
J. A. Hubbard ◽  
J. E. Brockmann ◽  
J. Dellinger ◽  
D. A. Lucero ◽  
A. L. Sanchez ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Flow Regime ◽  
Transition Flow ◽  
Fibrous Filter ◽  
Filter Efficiency ◽  
Transition Flow Regime

Experimental Study and Computational Fluid Dynamics Modeling of Pulp Suspensions Flow in a Pipe

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Carla Cotas ◽  
Bruno Branco ◽  
Dariusz Asendrych ◽  
Fernando Garcia ◽  
Pedro Faia ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Flow Regime ◽  
Turbulent Regime ◽  
Cfd Model ◽  
Dynamics Modeling ◽  
Transition Flow ◽  
Pulp Suspensions ◽  
Transition Flow Regime

Eucalyptus and Pine suspensions flow in a pipe was studied experimentally and numerically. Pressure drop was measured for different mean inlet flow velocities. Electrical impedance tomography (EIT), was used to evaluate the prevailing flow regime. Fibers concentration distribution in the pipe cross section and plug evolution were inferred from EIT tomographic images. A modified low-Reynolds-number k–ε turbulence model was applied to simulate the flow of pulp suspensions. The accuracy of the computational fluid dynamics (CFD) predictions was significantly reduced when data in plug regime was simulated. The CFD model applied was initially developed to simulate the flow of Eucalyptus and Pine suspensions in fully turbulent flow regime. Using this model to simulate data in the plug regime leads to an excessive attenuation of turbulence which leads to lower values of pressure drop than the experimental ones. For transition flow regime, the CFD model could be applied successfully to simulate the flow data, similar to what happens for the turbulent regime.

On the drag of a flat plate at zero incidence in almost-free-molecule flow

1959 ◽  
Vol 5 (3) ◽  
pp. 481-490 ◽  
Author(s):  
V. C. Liu
Keyword(s):  
Flat Plate ◽  
Skin Friction ◽  
Flow Regime ◽  
Rarefied Gas ◽  
Approximate Theory ◽  
Free Molecule ◽  
Transition Flow ◽  
Rigid Spheres ◽  
Governing Parameter ◽  
Transition Flow Regime

A physical theory is proposed for the skin friction on a flat plate at zero incidence in the transition flow regime, i.e. in the flow of a moderately rarefied gas. The ratio of the molecular mean free path to the characteristic size of the plate is assumed of order unity or larger. A general formula for the perturbation to the well-known friction of the free-molecule theory is given. This perturbation is attributed to the intermolecular collisions which are neglected on the basis of the free-molecule hypothesis. The expected rate of collisions are calculated for rigid spheres, using the classical kinetic theory.Although this is intended as an approximate theory, the theoretical results check surprisingly well with the limited experimental data that are available. The present theory shows that the ratio of the Reynolds number to the Mach number squared is the governing parameter for determining the intermolecular collision effect on skin friction in the transition flow regime.

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