Experimental Investigation On Heat Transfer Enhancement Of Pulsating Flow

The problem of heat transfer in pulsating flow represents one class ofthe practical applications for unsteady heat transfer technology. Heattransfer in turbulent pulsating flow, which is the important part ofoscillatory heat transfer is lacking in study. The engineering technologieson this are restricted for the future development.A device for producing pulsating air flow named vane-type pulsationgenerator was imposed in this paper. Flow-rate measurement method ofpulsating flow was obtained. The thermal boundary condition was constantwall temperature by means of employing constant temperature water intank outside tube. The experimental setup for investigating heat transfer inturbulent pulsating flow was built based on these works.An experimental investigation has been conducted to study theperformance of heat transfer in turbulent pulsating flow with velocity andpulsation frequency ranging in 16～40 m/s, 0～100 Hz, respectively. The measurement errors for testing data were processed. The dimensionlesscorrelation numbers, which describe the characteristic of oscillatory heattransfer in turbulent flow were selected after reviewing the existentdimensionless parameters and correlations. Based on the ratio of inletpressure amplitude to outlet pressure amplitude for pulsating flow, a newnon-dimensional parameter called dimensionless pulsation amplitude wasdefined in the present dissertation. The relationships between Nusseltnumber and the factors including Reynolds number, Womersley numberand non-dimensional pulsation amplitude were analyzed. Grounded on thepresent data, a correlation, which reflects the laws of heat transfer inturbulent pulsating flow was obtained by means of linear regression. Thecorrelated degree of the equation was discussed using deviation comparisonand statistics method. The reasonable accurate range for the correlation wasgiven. The factors effecting heat transfer enhancement of turbulentpulsating flow, which include time-average velocity, pulsation frequencyand pulsation amplitude were analyzed for investigating the characteristicof heat transfer augmentation. Struggle direction of study and applicationsfor oscillatory heat transfer was presented at the end of the dissertation.