Data reduction of friction factor of compressible flow in micro-channels

Kawashima, Daisuke; Asako, Yutaka

doi:10.1016/j.ijheatmasstransfer.2014.05.009

Cited by 17 publications

(7 citation statements)

References 11 publications

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“…Local Fanning friction factor can be defined by the following expression for a compressible flow [18]:ff,local=4τw12ρu2=2Dhp−2Dhpρ2u2RTdpdx−2DhTdTdx where hydraulic diameter of a rectangular MC is defined as:Dh=4APer=2whw+h Reynolds number at the inlet of MC can then be calculated using measured mass flow rate and calculated viscosity at inlet temperature with the following equation:Re=truem˙DhμA Considering one dimensional flow of ideal gas, Equation (1) can be integrated between two points a and b along the length ( L ), to calculate average friction factor between those points as follows:ff=Dhxb−xa[]pa2−pb2RT…”

Section: Experimental Methodologymentioning

confidence: 99%

“…In reality, a gas microflow does not stay isothermal and shows a strong temperature decrease close to MC outlet even for adiabatic walls. In a high-speed gas microflow, placing a thermocouple in the outlet jet will measure a value between static and total temperature [18], and therefore direct measurement is still challenging. Fortunately for an adiabatic flow, static temperature estimation at MC outlet can be done using a quadratic equation proposed by Kawashima and Asako [18].…”

Section: Introductionmentioning

confidence: 99%

“…In a high-speed gas microflow, placing a thermocouple in the outlet jet will measure a value between static and total temperature [18], and therefore direct measurement is still challenging. Fortunately for an adiabatic flow, static temperature estimation at MC outlet can be done using a quadratic equation proposed by Kawashima and Asako [18]. By incorporating temperature gradient along the length of MC, it was shown numerically that local friction factor for nitrogen gas in microtubes (MTs) is in good agreement with conventional theory not only in laminar but also in the high-speed turbulent flow regime.…”

Section: Introductionmentioning

confidence: 99%

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A Comparison of Data Reduction Methods for Average Friction Factor Calculation of Adiabatic Gas Flows in Microchannels

2019

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In this paper, a combined numerical and experimental approach for the estimation of the average friction factor along adiabatic microchannels with compressible gas flows is presented. Pressure-drop experiments are performed for a rectangular microchannel with a hydraulic diameter of 295 μ m by varying Reynolds number up to 17,000. In parallel, the calculation of friction factor has been repeated numerically and results are compared with the experimental work. The validated numerical model was also used to gain an insight of flow physics by varying the aspect ratio and hydraulic diameter of rectangular microchannels with respect to the channel tested experimentally. This was done with an aim of verifying the role of minor loss coefficients for the estimation of the average friction factor. To have laminar, transitional, and turbulent regimes captured, numerical analysis has been performed by varying Reynolds number from 200 to 20,000. Comparison of numerically and experimentally calculated gas flow characteristics has shown that adiabatic wall treatment (Fanno flow) results in better agreement of average friction factor values with conventional theory than the isothermal treatment of gas along the microchannel. The use of a constant value for minor loss coefficients available in the literature is not recommended for microflows as they change from one assembly to the other and their accurate estimation for compressible flows requires a coupling of numerical analysis with experimental data reduction. Results presented in this work demonstrate how an adiabatic wall treatment along the length of the channel coupled with the assumption of an isentropic flow from manifold to microchannel inlet results in a self-sustained experimental data reduction method for the accurate estimation of friction factor values even in presence of significant compressibility effects. Results also demonstrate that both the assumption of perfect expansion and consequently wrong estimation of average temperature between inlet and outlet of a microchannel can be responsible for an apparent increase in experimental average friction factor in choked flow regime.

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Section: Experimental Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Comparison of Data Reduction Methods for Average Friction Factor Calculation of Adiabatic Gas Flows in Microchannels

2019

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“…Therefore, the static gas temperature should be obtained by another way to calculate the friction factor. The equation to estimate the static gas temperature proposed by Kawashima and Asako 15 can be applied. Here, we consider one-dimensional compressible fluid flow in a micro-tube with adiabatic walls to derive an equation for estimation of the cross sectional average static gas temperature.…”

Section: Data Reductionmentioning

confidence: 99%

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

Kawashima

Asako

2015

Proceedings of the Institution of Mechanical Engineers, Part C:

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This paper presents experimental results on the friction factor of gaseous flow in a PEEK micro-tube with arithmetic mean roughness of 0.2 mm (relative surface roughness of 0.04%). The experiments were performed for nitrogen gas flow through the micro-tube with 514.4 mm 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.

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“…This is because of the measurement limitations in gas temperature flowing through micro-channels. Fortunately, for gas flow through a micro-channel with thermally insulated wall (adiabatic wall), the estimation of gas static temperature at the micro-channel outlet can be obtained using a quadratic equation proposed by Kawashima and Asako [10]. A new data reduction methodology for the average Fanning friction factor calculation between the inlet and outlet, considering the effect of the decrease in gas temperature, has been developed by Hong et al, [11].…”

Section: Introductionmentioning

confidence: 99%

Average Friction Factor for Laminar Gas Flow in Microtubes

Hong¹,

Asako²,

Faghri³

et al. 2020

CFDL

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The average friction factor in micro tubes will help the design engineers to estimate the pressure loss in micro flow devices. The aim of the present study is to obtain numerically average Darcy and Fanning friction factors and Mach numbers between the inlet and outlet of gas flows through adiabatic microtubes. This paper presents the average Poiseuille numbers, (fdRe)ave & (ffRe)ave, between the inlet and outlet, those are obtained from numerical results for laminar gas flow in microtubes with diameters of 50, 100 and 150 m and aspect ratios (i.e. length/diameter) of 100, 200 and 400, respectively. Axis-symmetric compressible momentum and energy equations were solved with the Arbitrary-Lagrangian-Eulerian (ALE) method. The stagnation pressure was chosen in such a way that the outlet Mach number ranged from 0.1 to 1.0. The outlet pressure was fixed at atmospheric condition. As a result, the average Darcy and Fanning friction factors between the inlet and outlet were obtained and compared with Moody's chart. The (fdRe)ave and (ffRe)ave were also obtained and presented as a function of average Mach number and were compared with the local fRe correlations proposed in the previous study.

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Data reduction of friction factor of compressible flow in micro-channels

Cited by 17 publications

References 11 publications

A Comparison of Data Reduction Methods for Average Friction Factor Calculation of Adiabatic Gas Flows in Microchannels

A Comparison of Data Reduction Methods for Average Friction Factor Calculation of Adiabatic Gas Flows in Microchannels

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

Average Friction Factor for Laminar Gas Flow in Microtubes

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