Pressure drop characteristics for turbulent flow in a straight circular tube situated downstream of a bend

Ohadi, Michael M.; Sparrow, E. M.; Walavalkar, Ajey Y.; Ansari, A. I.

doi:10.1016/0017-9310(90)90157-p

Cited by 7 publications

(6 citation statements)

References 4 publications

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“…Hence, the presence of the bend did not affect the fully developed friction factors. Similar results were also observed by Ohadi et al …”

Section: Resultssupporting

confidence: 92%

“…In the downstream of the bend, the pressure recovery lengths were found to be within 25 pipe diameter for the 45°, 90°, and 135°bends and within 25 pipe diameter for the 180°bend, depending on the flow rate. Ito 15 reported that the pressure drop starts to deviate from the developing flow 5-10 pipe diameters upstream of the inlet and gradually approaches the developing flow in the downstream straight section about 40-50 pipe diameter from the bend exit, whereas Ohadi et al 19 showed that the developing flow reached within 20 pipe diameter from the bend outlet.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Pressure Losses in Bends during Two-Phase Gas−Newtonian Liquid Flow

Mandal

Das

2001

Ind. Eng. Chem. Res.

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Experimental investigations have been carried out to evaluate the two-phase pressure drop across different types of bends in the horizontal plane for gas-Newtonian liquid flow. Four different Newtonian liquids were used for the experiments. Correlations have been developed to predict the two-phase friction factor as a function of various physical and dynamic variables of the system. Statistical analysis of the correlation suggests that the correlations are of acceptable accuracy.

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“…Hence, the presence of the bend did not affect the fully developed friction factors. Similar results were also observed by Ohadi et al …”

Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Pressure Losses in Bends during Two-Phase Gas−Newtonian Liquid Flow

Mandal

Das

2001

Ind. Eng. Chem. Res.

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“…Significant pressure losses are also associated with flow redistribution in the redeveloping flow section immediately after bends. These additional pressure losses (relative to developed flows) have been reported even as far as 20 pipe diameters downstream of bends 11 . Ward‐Smith et al 12 remarked that, for curvature to diameter ratios less than 3, the wake effect consequent upon flow detachment provides the highest contribution to the pressure gradient, while, contributions from secondary flows and bend length are less.…”

Section: Introductionmentioning

confidence: 98%

A review of drag reduction by additives in curved pipes for single‐phase liquid and two‐phase flows

Ayegba

Edomwonyi‐Otu

Yusuf

et al. 2020

Engineering Reports

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The effect of drag‐reducing agents (DRAs) on fluid flows in straight pipes has been well documented. Key among these is the effect of DRAs on turbulence statistics (Reynolds shear stress, turbulence intensity, streamwise and wall‐normal velocity fluctuation among others). These primary effects result in secondary effects such as modification of mean velocity profile and reduction in frictional losses (drag reduction, DR). Interestingly, in curved pipe flows, the characteristic of flow is more complex due to secondary flow, wake effects and under‐developed flow characteristics. Therefore, a review of investigations on the effect of DRAs in curved pipe flows is presented in this paper. The paper highlights the difference between DR in straight and curved conduits as well as the interaction between DRAs and flow characteristics of curved pipe flows. Proposed mechanisms of DR, and factors that influence their effectiveness also received attention. It was shown that significant DR can be achieved in curved pipes. A review of various experimental results revealed that DR by additives in curved pipes is generally lower than in straight pipes but with certain similarities. It decreases with increase in curvature ratio and is more pronounced in the transition and turbulent flow regimes. Maximum DR asymptote differed between straight and curved pipes and between polymer and surfactant. Due to the limited studies in the area of DR for gas‐liquid flow in curved pipes, no definite conclusion could be drawn on the effect of DRAs on such flows. A number of questions remain such as physical interaction between molecules of DRA and flow features such as secondary flow streamlines and wakes. Hence, some research gaps have been identified with recommendations for areas of future researches.

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“…Ohadi et al [7] have reported their study on effect of bend on pressure drop in a straight section downstream of a 180°bend. They found about 9% higher pressure drop in downstream section due to bend.…”

Section: Introductionmentioning

confidence: 98%

“…They found about 9% higher pressure drop in downstream section due to bend. Multi-stream Hampson heat exchanger with paired tubes reported by Kao [7] is helical coil type for three fluids. The paired tubes are soldered with tin-lead solder having thermal conductivity about 10% of copper, which may not be effective in liquid-liquid heat exchange due to its low thermal conductivity.…”

Section: Introductionmentioning

confidence: 99%