An experimental investigation regarding the laminar to turbulent flow transition in helically coiled pipes

Cioncolini, Andrea; Santini, Lorenzo

doi:10.1016/j.expthermflusci.2005.08.005

Cited by 168 publications

(119 citation statements)

References 9 publications

Supporting

Mentioning

106

Contrasting

Unclassified

Order By: Relevance

“…Experimental works were concentrated mainly on measuring pressure or temperature data and deducing characteristics of the helical pipe. Cioncolini and Santini 8 and Hayamizu et al 9 experimentally clarified the curvature and torsion effect on the flow in helical pipes from laminar to turbulent flow, respectively. Gupta et al, 10 Pimenta and Campos, 11 and Amicis et al 12 all measured the pressure drop for helical pipe under laminar flow condition.…”

Section: Introductionmentioning

confidence: 99%

A numerical study of flow characteristics in a helical pipe

Tang

Parameswaran

2016

Advances in Mechanical Engineering

View full text Add to dashboard Cite

Flow characteristics and loss mechanism inside the helical pipe with large-caliber and large-scale Dean number were analyzed in this study. Numerical simulation was carried out for exploring velocity distribution, pressure field, and secondary flow by varying coil parameters such as Dean number, curvature radius, and coil pitch. The velocity gradient in the cross-section increases along the pipe and causes unsteady flow in the pipe. Large pressure differences in the 180°and 315°cross-section generate centrifugal forces on the pipe. The secondary flow is the major factor resulting in flow loss, presented obviously by the streamlines to analyze the effects of pipe parameters on the vortices. The vortex center shifts toward the upper wall with the increase in Dean number and takes a slight deflection with the increase in coil pitch. Meanwhile, a correlation of the flow loss extent inside the pipe as a function of friction factor was presented. The increases in curvature radius and coil pitch can diminish the friction factor to reduce flow losses. The accuracy of the numerical methodology was also validated by conducting corresponding experiments and empirical mathematical analysis. The maximum deviation between the experimental values and the simulated results of the pressure drop is just 2.9%.

show abstract

Section: Introductionmentioning

confidence: 99%

A numerical study of flow characteristics in a helical pipe

Tang

Parameswaran

2016

Advances in Mechanical Engineering

View full text Add to dashboard Cite

show abstract

“…The conclusions of the different studies, in particular for Newtonian fluids, are multiple and, sometimes divergent, as is the case of the works of Ali [4] and Cioncolini and Santini [5] which refer the existence of two sub-regimes in the laminar flow. Besides the intention to clarify these divergent conclusions for Newtonian fluids, the main objective of the present study is to find accurate pressure drop correlations for non-Newtonian fluids flowing in helical coils with simultaneous heat transfer and particularly to study the contribution of the elastic component.…”

Section: Introductionmentioning

confidence: 99%

“…Reviewing these works, it is straightforward that there is a limited knowledge concerning the friction factor for nonNewtonian fluids flowing in coils, in particular about the effect of the viscoelasticity of the fluid. In the case of Newtonian fluids, there are still aspects not yet fully understood, including geometric effects and classification of flow regimes [4,5].…”

Section: Introductionmentioning

confidence: 99%

Friction losses of Newtonian and non-Newtonian fluids flowing in laminar regime in a helical coil

Pimenta¹,

Campos

2012

Experimental Thermal and Fluid Science

View full text Add to dashboard Cite

a b s t r a c tThis study aimed to carry out experimental work to determine, for Newtonian and non-Newtonian fluids, the friction factor (f c ) with simultaneous heat transfer, at constant wall temperature as boundary condition, in fully developed laminar flow inside a vertical helical coil. The Newtonian fluids studied were aqueous solutions of glycerol, 25%, 36%, 43%, 59% and 78% (w/w). The non-Newtonian fluids were aqueous solutions of carboxymethylcellulose (CMC), a polymer, with concentrations of 0.2%, 0.3%, 0.4% and 0.6% (w/w) and aqueous solutions of xanthan gum (XG), another polymer, with concentrations of 0.1% and 0.2% (w/w). According to the rheological study done, the polymer solutions had shear-thinning behavior and different values of viscoelasticity. The helical coil used has an internal diameter, curvature ratio, length and pitch, respectively: 0.00483 m, 0.0263, 5.0 m and 11.34 mm. It was concluded that the friction factors, with simultaneous heat transfer, for Newtonian fluids can be calculated using expressions from literature for isothermal flows. The friction factors for CMC and XG solutions are similar to those for Newtonian fluids when the Dean number, based in a generalized Reynolds number, is less than 80. For Dean numbers higher than 80, the friction factors of the CMC solutions are lower those of the XG solutions and of the Newtonian fluids. In this range the friction factors decrease with the increase of the viscometric component of the solution and increase for increasing elastic component. The change of behavior at Dean number 80, for Newtonian and non-Newtonian fluids, is in accordance with the study of Ali [4]. There is a change of behavior at Dean number 80, for Newtonian and non-Newtonian fluids, which is in according to previous studies. The data also showed that the use of the bulk temperature or of the film temperature to calculate the physical properties of the fluid has a residual effect in the friction factor values.

show abstract

“…This new prediction method is very simple to implement, as it is based on the homogeneous flow model, is asymptotically consistent with straight tube two-phase flows and is largely superior in accuracy to existing prediction methods. The present study is part of a wide research program addressing single and two-phase boiling flows in helically coiled tubes, focusing in particular on the design and operation of compact once-through steam generators with in-tube boiling for nuclear power applications, notably small modular units [22,23,[27][28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Two-phase pressure drop prediction in helically coiled steam generators for nuclear power applications

Cioncolini

Santini

2016

International Journal of Heat and Mass Transfer

Self Cite

View full text Add to dashboard Cite

This study considers the prediction of the pressure gradient with water-steam two-phase flows through helically coiled steam generator tubes, focusing in particular on the operating conditions of low-medium pressure, low mass flux and low heat flux typical of once-through steam generators with in-tube boiling adopted in small modular nuclear reactor systems. Twenty-five widely used empirical correlations have been tested against an experimental pressure drop databank drawn together in this study containing 980 data points. Since no existing correlation is capable of collapsing and satisfactorily fitting the collected databank, a new pressure drop prediction method for helically coiled tubes is proposed. This new prediction method is very simple to implement, as it is based on the homogeneous flow model, is asymptotically consistent with straight tube twophase flows and is largely superior in accuracy to existing prediction methods (mean absolute error of 7.3%, and 9 points out of 10 captured to within ±15%). The new prediction method is applicable for operating pressures in the range of 0.75-9.0 MPa, mass fluxes from 400 kg/m 2 s to 1191 kg/m 2 s, heat fluxes up to 750 kW/m 2 , tube diameters within 5-20 mm and coil to tube diameter ratio above 32.4. Curvature effects on the pressure gradient in helical coil two-phase flows can be significant, particularly with high velocity flows in tight curvature coils where the centrifugal force is intense.2

show abstract

An experimental investigation regarding the laminar to turbulent flow transition in helically coiled pipes

Cited by 168 publications

References 9 publications

A numerical study of flow characteristics in a helical pipe

A numerical study of flow characteristics in a helical pipe

Friction losses of Newtonian and non-Newtonian fluids flowing in laminar regime in a helical coil

Two-phase pressure drop prediction in helically coiled steam generators for nuclear power applications

Contact Info

Product

Resources

About