为了研究乳化沥青的流变性,采用旋转桨粘度计测试了20~50℃和45~100 r/min下乳化沥青试样的表观粘度,分别拟合了试样的表观粘度与温度、表观粘度与剪切速率的关系,根据Andrade公式计算了试样的表观流动活化能。结果表明,在试验条件下,...为了研究乳化沥青的流变性,采用旋转桨粘度计测试了20~50℃和45~100 r/min下乳化沥青试样的表观粘度,分别拟合了试样的表观粘度与温度、表观粘度与剪切速率的关系,根据Andrade公式计算了试样的表观流动活化能。结果表明,在试验条件下,浓度为60.75%的乳化沥青为假塑性流体,浓度为54.33%的乳化沥青为牛顿型流体;表观粘度随温度的升高呈指数规律下降;表观流动活化能分别为9.15 k J/mol和8.30 k J/mol。展开更多
The impact of boundary layer suction on the aerodynamic performance of a high-turning compressor cascade was numerically simulated and discussed.The aerodynamic performance of a curved and a straight cascade with and ...The impact of boundary layer suction on the aerodynamic performance of a high-turning compressor cascade was numerically simulated and discussed.The aerodynamic performance of a curved and a straight cascade with and without boundary layer suction were comparatively studied at several suction flow rates.The results showed that boundary layer suction dramatically improved the flow behavior within the flow passage.Moreover,higher loading over the whole blade height,lower total pressure loss,and higher passage throughflow were achieved with a relatively small amount of boundary layer removal.The integration of curved blade and boundary layer suction contributed to better aerodynamic performance than the cascades with only curved blade or boundary layer suction used,and the more favorable effect resulted from the weakening of the three dimensional effects of the boundary layer close to the endwalls.展开更多
The authors have invented the unique counter-rotating type tidal stream power unit composed of the tandem pro- peUers and the double rotational armature type peculiar generator without the traditional stator. The fron...The authors have invented the unique counter-rotating type tidal stream power unit composed of the tandem pro- peUers and the double rotational armature type peculiar generator without the traditional stator. The front and the rear propellers counter-drive the inner and the outer armatures of the peculiar generator, respectively. The unit has the fixftful advantages that not only the output is sufficiently higher without supplementary equipment such as a gearbox, but also the rotational moment hardly act on the pillar because the rotational torque of both propel- lers/armatures are counter-balanced in the unit. This paper discusses experimentally the performances of the power unit and the effects of the propeller rotation on the sea surface. The axial force acting on the pillar in- creases naturally with the increase of not only the stream velocity but also the drag of the tandem propellers. Be- sides, the force vertical to the stream also acts on the pillar, which is induced from the Karman vortex street and the dominant frequencies appear owing to the front and the rear propeller rotations. The propeller rotating in close to the sea surface brings the abnormal wave and the amplitude increases as the stream velocity is faster and/or the drag is stronger.展开更多
Small propeller-type wind turbines have a low Reynolds number,limiting the number of usable airfoil materials.Thus,their design method is not sufBciently established,and their performance is often low.The ultimate goa...Small propeller-type wind turbines have a low Reynolds number,limiting the number of usable airfoil materials.Thus,their design method is not sufBciently established,and their performance is often low.The ultimate goal of this research is to establish high-performance design guidelines and design methods for small propeller-type wind turbines.To that end,we designed two rotors:Rotor A,based on the rotor optimum design method from the blade element momentum theory,and Rotor B,in which the chord length of the tip is extended and the chord length distribution is linearized.We examined performance characteristics and flow fields of the two rotors through wind tunnel experiments and numerical analysis.Our results revealed that the maximum output tip speed ratio of Rotor B shifted lower than that of Rotor A,but the maximum output coefficient increased by approximately 38.7%.Rotors A and B experienced a large-scale separation on the hub side,which extended to the mean in Rotor A.This difference in separation had an impact on the significant decrease in Rotor A's output compared to the design value and the increase in Rotor B's output compared to Rotor A.展开更多
文摘为了研究乳化沥青的流变性,采用旋转桨粘度计测试了20~50℃和45~100 r/min下乳化沥青试样的表观粘度,分别拟合了试样的表观粘度与温度、表观粘度与剪切速率的关系,根据Andrade公式计算了试样的表观流动活化能。结果表明,在试验条件下,浓度为60.75%的乳化沥青为假塑性流体,浓度为54.33%的乳化沥青为牛顿型流体;表观粘度随温度的升高呈指数规律下降;表观流动活化能分别为9.15 k J/mol和8.30 k J/mol。
基金Sponsored by the National Natural Science Foundation of China(Grant No.50646021).
文摘The impact of boundary layer suction on the aerodynamic performance of a high-turning compressor cascade was numerically simulated and discussed.The aerodynamic performance of a curved and a straight cascade with and without boundary layer suction were comparatively studied at several suction flow rates.The results showed that boundary layer suction dramatically improved the flow behavior within the flow passage.Moreover,higher loading over the whole blade height,lower total pressure loss,and higher passage throughflow were achieved with a relatively small amount of boundary layer removal.The integration of curved blade and boundary layer suction contributed to better aerodynamic performance than the cascades with only curved blade or boundary layer suction used,and the more favorable effect resulted from the weakening of the three dimensional effects of the boundary layer close to the endwalls.
文摘The authors have invented the unique counter-rotating type tidal stream power unit composed of the tandem pro- peUers and the double rotational armature type peculiar generator without the traditional stator. The front and the rear propellers counter-drive the inner and the outer armatures of the peculiar generator, respectively. The unit has the fixftful advantages that not only the output is sufficiently higher without supplementary equipment such as a gearbox, but also the rotational moment hardly act on the pillar because the rotational torque of both propel- lers/armatures are counter-balanced in the unit. This paper discusses experimentally the performances of the power unit and the effects of the propeller rotation on the sea surface. The axial force acting on the pillar in- creases naturally with the increase of not only the stream velocity but also the drag of the tandem propellers. Be- sides, the force vertical to the stream also acts on the pillar, which is induced from the Karman vortex street and the dominant frequencies appear owing to the front and the rear propeller rotations. The propeller rotating in close to the sea surface brings the abnormal wave and the amplitude increases as the stream velocity is faster and/or the drag is stronger.
文摘Small propeller-type wind turbines have a low Reynolds number,limiting the number of usable airfoil materials.Thus,their design method is not sufBciently established,and their performance is often low.The ultimate goal of this research is to establish high-performance design guidelines and design methods for small propeller-type wind turbines.To that end,we designed two rotors:Rotor A,based on the rotor optimum design method from the blade element momentum theory,and Rotor B,in which the chord length of the tip is extended and the chord length distribution is linearized.We examined performance characteristics and flow fields of the two rotors through wind tunnel experiments and numerical analysis.Our results revealed that the maximum output tip speed ratio of Rotor B shifted lower than that of Rotor A,but the maximum output coefficient increased by approximately 38.7%.Rotors A and B experienced a large-scale separation on the hub side,which extended to the mean in Rotor A.This difference in separation had an impact on the significant decrease in Rotor A's output compared to the design value and the increase in Rotor B's output compared to Rotor A.
