Measurement of quasi-local friction factor of gas flow in a micro-tube

2015 ◽  
Vol 230 (5) ◽  
pp. 782-792 ◽  
Author(s):  
D Kawashima ◽  
Y Asako
Keyword(s):  
Friction Factor ◽  
Gas Flow ◽  
Tube Wall ◽  
Flow Region ◽  
Arithmetic Mean ◽  
Nitrogen Gas ◽  
Gaseous Flow ◽  
Flow Through ◽  
Local Pressures ◽  
Measured Pressure

This paper presents experimental results on the friction factor of gaseous flow in a PEEK micro-tube with arithmetic mean roughness of 0.2 µm (relative surface roughness of 0.04%). The experiments were performed for nitrogen gas flow through the micro-tube with 514.4 µm in diameter and 50 mm in length. Three pressure tap holes were drilled on the PEEK micro-tube wall at intervals of 5 mm and the local pressures were measured. The quasi-local friction factor is obtained from the measured pressure differences. The experiments were conducted in the turbulent flow region. The quasi-local friction factor obtained from the present study is compared with those in the available literature and also numerical results. The quasi-local friction factor obtained is 12–20% higher than the value predicted from the Blasius formula.

Measurement of Semi-Local Friction Factor of Gas Flow in Micro-Tube

2013 ◽  
Author(s):  
D. Kawashima ◽  
Y. Asako
Keyword(s):  
Surface Roughness ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Gas Flow ◽  
Flow Region ◽  
Nitrogen Gas ◽  
Gaseous Flow ◽  
Flow Through ◽  
Local Pressures ◽  
Measured Pressure

This paper presents experimental results on friction factor of gaseous flow in a PEEK micro-tube with relative surface roughness of 0.04 %. The experiments were performed for nitrogen gas flow through the micro-tube with 514.4 μm in diameter and 50 mm in length. Three pressure taps holes with 5 mm interval were drilled and the local pressures were measured. Friction factor is obtained from the measured pressure differences. The experiments were conducted for turbulent flow region. The friction factor obtained by the present study are compared with those in available literature and also numerical results. The friction factor obtained is slightly higher than the value of Blasius formula.

Experimental Investigations on Friction Factors of Gaseous Flow Through a Micro-Tube With Smooth Surface

2017 ◽  
Author(s):  
Takayuki Shigeishi ◽  
Chungpyo Hong ◽  
Yutaka Asako
Keyword(s):  
Friction Factor ◽  
Smooth Surface ◽  
Gas Flow ◽  
Experimental Investigations ◽  
Adiabatic Wall ◽  
Choked Flow ◽  
Friction Factors ◽  
Wide Range ◽  
Flow Through ◽  
Local Pressures

The purpose of the present study is to experimentally investigate flow characteristics on semi-local friction factors of nitrogen gas flow through a micro-tube with a smooth surface. The experiments were performed using a glass micro-tube with 266 μm in diameter and 120 mm in length. Three static pressure holes are drilled on the wall near the micro-tube outlet at intervals of 5 mm, and the local pressures were measured with the outlet discharged into the atmosphere. The local values of Mach number, temperature and friction factor were obtained from the measured local pressures. The result in the wide range of Reynolds number was also obtained, including the choked flow. Darcy friction factor and Fanning friction factor obtained under the assumptions of both a Fanno flow (adiabatic wall) and an Isothermal flow were compared with empirical correlations in the literature and numerical results.

Semi Local Friction Factor of Gas Flow Through a Micro-Tube

2017 ◽  
Author(s):  
Kenshi Maeda ◽  
Chungpyo Hong ◽  
Yutaka Asako
Keyword(s):  
Friction Factor ◽  
High Speed ◽  
Gas Flow ◽  
Electrical Discharge Machining ◽  
Tube Wall ◽  
Gas Temperature ◽  
Local Pressure ◽  
Adiabatic Wall ◽  
Friction Factors ◽  
Flow Through

Flow characteristics of laminar gas flow through a micro-tube were experimentally studied on friction factors in this paper. The experiments were performed for nitrogen flow through a stainless steel micro-tube with 123.87 μm in diameter and 50mm in length. Two static pressure tap holes were fabricated on the micro-tube wall at intervals of 5mm with electrical discharge machining. The local pressure was measured to determine the local values of Mach number, temperature and friction factor. Both the Fanning and the Darcy friction factors were obtained under the assumption of a Fanno flow (adiabatic wall) since the external micro-tube wall was covered with the foamed polystyrene. The effects of temperature decrease on friction factors were investigated because the gas temperature steeply decreases near the outlet due to energy conversion from thermal energy into kinetic energy in a high speed gas flow. The obtained friction factors were compared with those in the available literature and also with numerical results.

Local Pressure Measurement of Gaseous Flow Through Microchannels

1999 ◽  
Author(s):  
Stephen E. Turner ◽  
Hongwei Sun ◽  
Mohammad Faghri ◽  
Otto J. Gregory
Keyword(s):  
Reynolds Number ◽  
Pressure Distribution ◽  
Friction Factor ◽  
Knudsen Number ◽  
Flow Region ◽  
Reynolds Numbers ◽  
Helium Flow ◽  
Local Pressure ◽  
Pressure Losses ◽  
Flow Through

Abstract This paper presents an experimental investigation on nitrogen and helium flow in microchannels etched in silicon with hydraulic diameters of 9.7, 19.6, and 46.6 μm, and Reynolds numbers ranging from 0. 2 to 1000. The objectives of this research are (1) to measure the pressure distribution along the length of a microchannel; and (2) to determine the friction factor within the fully developed region of the microchannel. The pressure distribution is presented as absolute local pressure plotted against the distance from the microchannel inlet. The friction factor results are presented as the product of friction factor and Reynolds number plotted against Reynolds number with the outlet Knudsen number, Kn, as a curve parameter. The following conclusions have been reached in the present investigation: (1) Pressure losses at the microchannel entrance can be significant; (2) the product, f*Re, when measured sufficiently far away from the entrance and exit is a constant in the laminar flow region; and (3) the friction factor decreases as the Knudsen number increases.

Friction Factor for Isothermal and Nonisothermal Flow Through Porous Media

1977 ◽  
Vol 99 (3) ◽  
pp. 367-373 ◽  
Author(s):  
J. C. Koh ◽  
J. L. Dutton ◽  
B. A. Benson ◽  
A. Fortini
Keyword(s):  
Reynolds Number ◽  
Porous Media ◽  
Friction Factor ◽  
Nonisothermal Flow ◽  
Flow Through Porous Media ◽  
Gaseous Flow ◽  
Pressure Drops ◽  
Flow Through ◽  
Temperature Levels ◽  
Nonisothermal Conditions

Measurements were performed to determine the pressure drops for gaseous flow through porous materials of different microstructures, porosities, and thickness under isothermal and nonisothermal conditions at various temperature levels. Results were satisfactorily correlated by a simple equation relating the friction factor to the Reynolds number and porosities.

Measurements of Two-Phase Pressure Drop in a Simulated Debris Bed

2017 ◽  
Author(s):  
Milka Hebi Nava Rivera ◽  
Daisuke Ito ◽  
Yasushi Saito ◽  
Mitsuhiro Aoyagi ◽  
Kenji Kamiyama ◽  
...  
Keyword(s):  
Porous Media ◽  
Pressure Drop ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Severe Accident ◽  
Phase Flow ◽  
Two Phase ◽  
Experimental Database ◽  
Flow Through ◽  
Measured Pressure

Two-phase flow through porous media should be well understood to develop a severe accident analysis code not only for light water reactor but also sodium cooled fast reactor (SFR). When a core disruptive accident occurs in SFR, the fuel inside the core may become melted and interacts with the coolant. As a result, gas-liquid two-phase flow will be formed in the debris bed, which may have porous nature depending on the cooling process. Thus, as first step, present work focuses on the characteristics of pressure drop in single- and two-phase flows in different porous media conditions (porous size, liquid and gas flow velocity). In addition, in order to construct an experimental database, the measured pressure drop under different conditions was compared with existing correlations.

A Criterion for the Experimental Validation of the Slip-Flow Models for Incompressible Rarefied Gases Through Microchannels

2004 ◽  
Author(s):  
G. L. Morini ◽  
M. Lorenzini ◽  
M. Spiga
Keyword(s):  
Friction Factor ◽  
Cross Section ◽  
Gas Flow ◽  
Experimental Validation ◽  
Rarefied Gas ◽  
Slip Flow ◽  
Rarefied Gas Flow ◽  
Flow Models ◽  
Flow Through ◽  
Rarefaction Effects

This paper is devoted to analyzing the friction factor of incompressible rarefied gas flow through microchannels. A theoretical investigation is conducted in order to underline the conditions for experimentally evidencing rarefaction effects on the pressure drop. It is demonstrated that for a fixed geometry of the microchannel cross section it is possible to calculate the minimum value of the Knudsen number for which the rarefaction effects can be observed experimentally, taking into account the experimental uncertainties on the evaluation of the friction factor.

Effect of Compressibility on Heat Transfer in Microchannels

2004 ◽  
Author(s):  
Stephen E. Turner ◽  
Yutaka Asako ◽  
Mohammad Faghri
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Temperature Sensors ◽  
Gas Temperature ◽  
Gaseous Flow ◽  
Thermal Boundary Conditions ◽  
Temperature Heat ◽  
Constant Wall Heat Flux ◽  
Flow Through ◽  
2D Numerical Model

In this paper an experimental investigation of convective heat transfer is presented for laminar gas flow through a microchannel. A test stand was setup to impose thermal boundary conditions of constant temperature gradient along the microchannel length. Additionally, thin film temperature sensors were developed and used to directly measure the microchannel surface temperature. Heat transfer experiments were conducted in the laminar flow regime with the outlet Ma between 0.10 and 0.42. The experimental measurements of inlet and outlet gas temperature and the microchannel wall temperature were used to validate a 2D numerical model for gaseous flow in microchannel. The model was then used to determine bcal values of Ma, Re, and Nu. The numerical results show that after the entrance region, Nu approaches 8.23, the fully developed value of Nu for incompressible flow for constant wall heat flux if Nu is defined based on (Tw-Taw) and plotted as a function of the new dimensionless axial length, X* = (x/2H)(Ma2)/(RePr).

Gas Flow Through Cracks

1978 ◽  
Vol 100 (4) ◽  
pp. 453-458 ◽  
Author(s):  
B. L. Button ◽  
A. F. Grogan ◽  
T. C. Chivers ◽  
P. T. Manning
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Gas Flow ◽  
Roughness Parameter ◽  
Parallel Cracks ◽  
Upstream Pressure ◽  
Theoretical Predictions ◽  
Laminar And Turbulent Flow ◽  
Temperature Ranges ◽  
Flow Through

Nitrogen flow through 13 idealized cracks has been measured and compared with theoretical predictions. Gas conditions covered upstream pressure and temperature ranges of between 10 and 50 bars and 277 and 295°K, respectively, exhausting to atmosphere. Hydraulic smooth, convergent and parallel cracks and rough parallel cracks were tested for depths varying from 6 to 810 μm. The effect of area change is adequately predicted from theory if a friction factor Reynolds number relationship is assumed. The remaining data are presented on the basis of a friction factor, Reynolds number, and hydraulic diameter/surface roughness parameter basis. Theoretical predictions are successful where roughness and flow are high enough for the results to be in the completely turbulent regimes. For the hydraulic smooth parallel cracks the flow is lower than predicted for laminar and turbulent flow and this discrepancy will be the subject for further investigations.

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