Flow resistance of low-frequency pulsatile turbulent flow in mini-channels

A Comment on Unsteady–periodic Flow Friction Factor: An Analysis on Experimental Data Gathered in Pulsatile Pipe Flows

“…Mel-Moody Diagram provides a considerable practice for the calculation of periodic flow friction factors in the range of Womersley number > 1.32 as listed below: • Zhuang et al's [27] mini channel (pointwise) transitional range study is confirming the change observed for laminar regime variation through proposed equations 9.b and 9.c. Zhuang et al's [28] study is also confirming the physical fact in turbulent regime.…”

“…, = , ( ) inside turbulent flow for ≥ 23763. These definitions are conceptually similar to the one introduced by Zhuang et al [27,28] for their analysis on transitional and turbulent low frequency pulsatile flows in narrow mini channels. Thus Equation 7.a can be given as follows: = ( ) (9.a)…”

“…Variation of λu,ta with Mel inside turbulent sinusoidal flow as a function of Reta for 2.72 ≤ √ ′ ≤ 28 and 0.05 ≤ A1 ≤ 0.96Sinusoidal flow regime limits can be given by 8208 ≤ ≤ 75644 for laminar case at low Reta and 51000 ≤ ≤ 280000 at = 10000. Meanwhile turbulent cases have the range of 178500 ≤ ≤ 1680000. complete the discussion with a general functional relationship valid for periodic flows, a modified friction multiplier λMel which is the same of Zhuang et al's friction ratio C is defined with an emphasis on flow regime as follows: These definitions are conceptually similar to the one introduced by Zhuang et al[27,28] for their analysis on transitional and turbulent low frequency pulsatile flows in narrow mini channels. Thus Equation 7.a can be given as follows: log plot of Equation 9.a is given inFigure 3.…”

“…In our analysis a similar argument is observed for laminar pulsatile flow in the range of 51000 ≤ ≤ 200000. In [28] they considered turbulent pulsatile flow characteristics to determine turbulence generation mechanism as a major function of aspect ratio of mini channels. They determined a variety of C magnitudes as maximum ones in the interactive influence of Womersley Number and oscillation amplitude A1.…”

Study on the Effect of Diaphragm Booster on the Pulsed Heat Transfer of Cooling System

“…In the study of pulsating heat transfer, the average speed of the pulsating flow, the pulsating frequency, and the pulsating amplitude can be controlled by adjusting the speed of the motor to enhance the heat transfer [1]. However, because of the frequency modulation of the motor and the transmission of fluid by the pipeline pump, electrical energy is required, and energy consumption is high [2]. The traditional pulsation generating device generally adopts a method such as a solenoid valve or a reciprocating pump.…”