| Title |
Heat Transfer Coefficient and Shear Factor Subjected to Both Oscillating Flow and Oscillating Pressure in Pulse Tubes |
| Keywords |
맥동관 ; 열전달계수 ; 전단계수 ; 주기적인 압력 ; 주기적인 유동 Pulse tube ; Heat transfer coefficient ; Shear factor ; Oscillating pressure ; Oscillating flow |
| Abstract |
Heat transfer and momentum transfer under conditions of both oscillating flow and oscillating pressure within pulse tubes show very different behavior from those for steady state conditions. The analytic solutions of axial velocity and temperature of the gas within pulse tubes were obtained by assuming that the variations in pressure and temperature were purely sinusoidal and small. The shear stress and the heat flux at the tube wall obtained from the solutions are expressed in terms of the cross-sectional averaged velocity, the difference between mean temperature and instantaneous cross-sectional averaged temperature and the difference between mean pressure and instantaneous pressure. It is shown that the complex shear factor, which has been applied to momentum transfer of incompressible oscillating flow, and the complex Nusselt number, which has been applied to either heat transfer with oscillating pressure only or heat transfer of incompressible oscillating flow, could also be used for momentum transfer and heat transfer subjected to both oscillating flow and oscillating pressure, respectively. |