scholarly journals EXPERIMENTAL STUDIES ON PRESSURE DROP CHARACTERIZATION OF CURVED TUBE SECTIONS IN LAMINAR FLOW REGIME

2020 ◽  
Vol 6 (4) ◽  
pp. 544-558
Author(s):  
Vikram KOLHE ◽  
Asmita DESHPANDE ◽  
Ravindra EDLABADKAR
Keyword(s):  
Pressure Drop ◽  
Laminar Flow ◽  
Flow Regime ◽  
Experimental Studies ◽  
Laminar Flow Regime ◽  
Curved Tube

Transition Criteria for Laminar to Turbulent Flow for Yield Power Law (YPL) Fluids Based on Stability Analysis

2013 ◽  
Author(s):  
Goktug Kalayci ◽  
Evren M. Ozbayoglu ◽  
Stefan Z. Miska ◽  
Mengjiao Yu ◽  
Nicholas Takach ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Stability Analysis ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Friction Factor ◽  
Yield Stress ◽  
Flow Regime ◽  
Power Law ◽  
Laminar Flow Regime

It is well known that a Newtonian fluid with the presence of solid particles in suspension behaves non-Newtonian. Higher the solid content, more significant the yield stress of the fluid. Determination of the hydraulic behavior of fluids having a significant yield stress is a challenging task. For engineering purposes, pressure drop within the system, during pipeline transportation, has to be estimated carefully and accurately. Flow regime plays a vital role during hydraulic calculations. The inaccurate determination of flow regime can lead us to large errors in frictional pressure drop calculations and ultimately leads to error in designing and flow assurance point of view, since hydraulic calculations are including a friction factor term, which is a direct function of flow regime. In general, Reynolds number is the main parameter used by the industry for determining the flow regime, and the friction factor. This approach works reasonably accurate for Newtonian fluids. However, as the yield stress of the fluid increases, this conventional technique for determining the flow regime is not as accurate. Although many approaches have been introduced for estimating the flow regime for non-Newtonian fluids, there exists a lack of information and confidence of such predictions for fluids having high yield stress, such as Yield Power Law (YPL) fluids (i.e., Herchel-Bulkley). (1)τ=τy+Kγm This study presents an analytical solution for predicting the transition from laminar to non-laminar flow regime based on Ryan & Johnson’s approach using the stability analysis and equation of motion for YPL fluids. Comparing with the experimental results for YPL fluids under different flow conditions, including laminar and non-laminar flow regimes, show that presented approach gives a better estimation of the transition from laminar to non-laminar flow regime than conventional Reynolds number approach. In some cases, it is observed that although the Reynolds number is high, flow is still laminar, which is predicted accurately using the presented model. This study provides a higher accuracy in estimating the flow regime, which leads to a higher confidence in hydraulic designs and determining limitations of the system in concern.

Relationship Between Pressure Drop and Heat Transfer of Fully Developed Flow in Smooth Horizontal Circular Tubes and Spiral Coiled Tubes in the Laminar Flow Regime

2021 ◽  
Author(s):  
Rahul H Patil ◽  
Mandar V Tendolkar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Flow Regime ◽  
Length Ratio ◽  
Dimensionless Group ◽  
Laminar Flow Regime ◽  
Friction Factors ◽  
Flow Through ◽  
Spiral Coils

Abstract Studies on isothermal steady state frictional pressure drop for flow of petroleum base oil SN70, SN150, Diesel and water are carried out in spiral coils with diameter to length ratio, 0.00042, 0.00047, 0.00073, 0.00164, 0.00189, 0.003 and 0.0037. An attempt is made to correlate friction factors with a better and more appropriate dimensionless group for flow of Newtonian fluids through spiral coiled tubes. An innovative approach of correlating heat transfer data with the newly established dimensionless group is presented. Heat transfer experiments are performed for spiral coils with diameter to length ratio 0.000474, 0.00042, 0.001896, 0.00198, 0.000942, 0.00164 in laminar flow regime. Suitable correlations for friction factors and Nusselt numbers are proposed. Relationship between pressure drop and heat transfer is studied. The incapability of the conventional analogy equations to estimate the heat and momentum transfer coefficients for laminar flow through straight or curved tubes is explained based on the viscous and form drag existing in straight and curved pipe flow. The limitations of the existing analogy equations are examined critically. A new general analogy equation is derived for laminar flow through spiral and straight tubes considering the influencing geometrical parameters of the tube. Keywords: Forced Convection; Heat and Mass transfer; Heat Exchangers; Thermal Systems.

scholarly journals Estimation of inspiratory pressure drop in neonatal and pediatric endotracheal tubes

1999 ◽  
Vol 87 (1) ◽  
pp. 36-46 ◽  
Author(s):  
Pierre-Henri Jarreau ◽  
Bruno Louis ◽  
Gilles Dassieu ◽  
Luc Desfrere ◽  
Perre W. Blanchard ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Laminar Flow ◽  
Flow Regime ◽  
Internal Diameter ◽  
Empirical Equations ◽  
Itô Formula ◽  
Ito Formula ◽  
Endotracheal Tubes ◽  
Curved Tube ◽  
Measured Pressure

Endotracheal tubes (ETTs) constitute a resistive extra load for intubated patients. The ETT pressure drop (ΔPETT) is usually described by empirical equations that are specific to one ETT only. Our laboratory previously showed that, in adult ETTs, ΔPETT is given by the Blasius formula (F. Lofaso, B. Louis, L. Brochard, A. Harf, and D. Isabey. Am. Rev. Respir. Dis. 146: 974–979, 1992). Here, we also propose a general formulation for neonatal and pediatric ETTs on the basis of adimensional analysis of the pressure-flow relationship. Pressure and flow were directly measured in seven ETTs (internal diameter: 2.5–7.0 mm). The measured pressure drop was compared with the predicted drop given by general laws for a curved tube. In neonatal ETTs (2.5–3.5 mm) the flow regime is laminar. The ΔPETT can be estimated by the Ito formula, which replaces Poiseuille’s law for curved tubes. For pediatric ETTs (4.0–7.0 mm), ΔPETT depends on the following flow regime: for laminar flow, it must be calculated by the Ito formula, and for turbulent flow, by the Blasius formula. Both formulas allow for ETT geometry and gas properties.

Heat transfer enhancement using second mode self-oscillating structures

2019 ◽  
Vol 30 (7) ◽  
pp. 3827-3842
Author(s):  
Samer Ali ◽  
Zein Alabidin Shami ◽  
Ali Badran ◽  
Charbel Habchi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Flow Regime ◽  
Vortex Generator ◽  
Reynolds Numbers ◽  
Content Type ◽  
Laminar Flow Regime ◽  
Second Mode

Purpose In this paper, self-sustained second mode oscillations of flexible vortex generator (FVG) are produced to enhance the heat transfer in two-dimensional laminar flow regime. The purpose of this study is to determine the critical Reynolds number at which FVG becomes more efficient than rigid vortex generators (RVGs). Design/methodology/approach Ten cases were studied with different Reynolds numbers varying from 200 to 2,000. The Nusselt number and friction coefficients of the FVG cases are compared to those of RVG and empty channel at the same Reynolds numbers. Findings For Reynolds numbers higher than 800, the FVG oscillates in the second mode causing a significant increase in the velocity gradients generating unsteady coherent flow structures. The highest performance was obtained at the maximum Reynolds number for which the global Nusselt number is improved by 35.3 and 41.4 per cent with respect to empty channel and rigid configuration, respectively. Moreover, the thermal enhancement factor corresponding to FVG is 72 per cent higher than that of RVG. Practical implications The results obtained here can help in the design of novel multifunctional heat exchangers/reactors by using flexible tabs and inserts instead of rigid ones. Originality/value The originality of this paper is the use of second mode oscillations of FVG to enhance heat transfer in laminar flow regime.

scholarly journals Numerical Prediction of Heat Transfer Characteristics of Nanofluids in a Minichannel Flow

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Arjumand Adil ◽  
Sonam Gupta ◽  
Pradyumna Ghosh
Keyword(s):  
Heat Transfer ◽  
Brownian Motion ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Computational Model ◽  
Flow Regime ◽  
Cfd Simulation ◽  
Computational Results ◽  
Heat Transfer Characteristics ◽  
Simulation Process

CFD simulation of the heat transfer and pressure drop characteristics of different nanofluids in a minichannel flow has been explained using FLUENT version 6.3.26. Different nanofluids with nanoparticles of Al2O3, CuO, SiO2, and TiO2have been used in the simulation process. A comparison of the experimental and computational results has been made for the heat transfer and pressure drop characteristics for the case of Al2O3-water nanofluid for the laminar flow. Also, computations have been made by considering Brownian motion as well as without considering Brownian motion of the nanoparticles. After verification of the computational model with the experimental results for Al2O3-water nanofluid, the simulations were performed for the same experimental readings for different nanofluids in the laminar flow regime to find out the heat transfer and pressure drop characteristics.

Sign in / Sign up

Export Citation Format

Share Document