Experimental study of convective heat transfer in pulsating air flow inside circular pipe

Experimental investigations for pulsating turbulent pipe air flow were carried out. A device for producing pulsatile air flow named vane-type pulsating flow generator was imposed to make the air flow from pump be in pulsating state. The thermal boundary condition in this paper was constant wall temperature by means of employing constant temperature water in tank outside tubes. New dimensionless amplitude definition, which is based on ratio of inlet pressure amplitude to outlet pressure amplitude was obtained for description of pulsation amplitude characteristics. The relationships between Nusselt number and the factors including Reynolds number Re, Womersley number W and non-dimensional pulsation amplitude A(o) were analyzed. Based on the experimental data, a correlation equation of time-averaged Nusselt number with dimensionless parameters of Re, A(o) and W is obtained for pulsating turbulent air flow inside a circular pipe. A close agreement between experimental data and correlated values from the equation was presented in this paper.