This study examines oblique wave motion over multiple submerged porous bars in front of a vertical wall. Based on linear potential theory, an analytical solution for the present problem is developed using matched eige...This study examines oblique wave motion over multiple submerged porous bars in front of a vertical wall. Based on linear potential theory, an analytical solution for the present problem is developed using matched eigenfunction expansions. A complex dispersion relation is adopted to describe the wave elevation and energy dissipation over submerged porous bars. In the analytical solution, no limitations on the bar number, bar size, and spacing between adjacent bars are set. The convergence of the analytical solution is satisfactory, and the correctness of the analytical solution is confirmed by an independently developed multi-domain BEM （boundary element method） solution. Numerical examples are presented to examine the reflection and transmission coefficients of porous bars, CR and Cv, respectively, for engineering applications. The calculation results show that when the sum of widths for all the porous bars is fixed, increasing the bar number can significantly improve the sheltering function of the bars. Increasing the bar height can cause more wave energy dissipation and lower CR and Cr. The spacing between adjacent bars and the spacing between the last bar and the vertical wall are the key parameters affecting CR and Ct. The proposed analytical method may be used to analyze the hydrodynamic performance of submerged porous bars in preliminary engineering designs.展开更多
An effective thermodynamic transformation analysis method was proposed in this study. According to the phenomenon of ex- ergy consumption always coupling with heat transfer process, the effective thermodynamic tempera...An effective thermodynamic transformation analysis method was proposed in this study. According to the phenomenon of ex- ergy consumption always coupling with heat transfer process, the effective thermodynamic temperatures were defined, then the actual power cycle or refrigeration/heat pump cycle was transformed into the equivalent reversible Carnot or reverse Carnot cycles for thermodynamic analysis. The derived effective thermodynamic temperature of the hot reservoir of the equivalent reverse Camot cycle is the basis of the proposed method. The combined diagram of TR-h and TR-q was adopted for the analy- sis of the system performance and the exergy consumption, which takes advantage of the visual expression of the heat/work exchange and the enthalpy change, and is convenient for the calculation of the coefficient of performance and exergy con- sumptions. Take a heat pump water heater with refrigerant of R22 for example, the proposed method was systematically intro- duced, and the fitting formulas of the effective thermodynamic temperatures were given as demonstration. The results show that the proposed method has advantage and well application foreground in the performance simulation and estimation under the variable working conditions.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51490675,51322903 and 51279224.)
文摘This study examines oblique wave motion over multiple submerged porous bars in front of a vertical wall. Based on linear potential theory, an analytical solution for the present problem is developed using matched eigenfunction expansions. A complex dispersion relation is adopted to describe the wave elevation and energy dissipation over submerged porous bars. In the analytical solution, no limitations on the bar number, bar size, and spacing between adjacent bars are set. The convergence of the analytical solution is satisfactory, and the correctness of the analytical solution is confirmed by an independently developed multi-domain BEM （boundary element method） solution. Numerical examples are presented to examine the reflection and transmission coefficients of porous bars, CR and Cv, respectively, for engineering applications. The calculation results show that when the sum of widths for all the porous bars is fixed, increasing the bar number can significantly improve the sheltering function of the bars. Increasing the bar height can cause more wave energy dissipation and lower CR and Cr. The spacing between adjacent bars and the spacing between the last bar and the vertical wall are the key parameters affecting CR and Ct. The proposed analytical method may be used to analyze the hydrodynamic performance of submerged porous bars in preliminary engineering designs.
基金supported by the National Natural Science Foundation of China (Grant No. 51076147)
文摘An effective thermodynamic transformation analysis method was proposed in this study. According to the phenomenon of ex- ergy consumption always coupling with heat transfer process, the effective thermodynamic temperatures were defined, then the actual power cycle or refrigeration/heat pump cycle was transformed into the equivalent reversible Carnot or reverse Carnot cycles for thermodynamic analysis. The derived effective thermodynamic temperature of the hot reservoir of the equivalent reverse Camot cycle is the basis of the proposed method. The combined diagram of TR-h and TR-q was adopted for the analy- sis of the system performance and the exergy consumption, which takes advantage of the visual expression of the heat/work exchange and the enthalpy change, and is convenient for the calculation of the coefficient of performance and exergy con- sumptions. Take a heat pump water heater with refrigerant of R22 for example, the proposed method was systematically intro- duced, and the fitting formulas of the effective thermodynamic temperatures were given as demonstration. The results show that the proposed method has advantage and well application foreground in the performance simulation and estimation under the variable working conditions.
