An experimental investigation of the tip flow characteristics between a gas turbine blade tip and the shroud was conducted by a pressure-test system and a particle image velocimetry(PIV)system.A three-times scaled pro...An experimental investigation of the tip flow characteristics between a gas turbine blade tip and the shroud was conducted by a pressure-test system and a particle image velocimetry(PIV)system.A three-times scaled profile of the GE-E3 blade with five film cooling holes was used as specimen.The effects on flow characteristics by the rim width and the groove depth of the squealer tip were revealed.The rim widths were(a)0.9%,(b)2.1%,and(c)3.0%of the axial chord,and the groove depths were(a)2.8%,(b)4.8%,and(c)10%of the blade span.Several pressure taps on the top plate above the blades were connected to pressure gauges.By a CCD camera the PIV system recorded the velocity field around the leading edge zone including the five cooling holes.The flow distributions both in the tip clearance and in the passage were revealed,and the influence of the inlet velocity was determined.In this work,the tip flow characteristics with and without film cooling were investigated.The effects of different global blowing ratios of M=0.5,1.0,1.3 and 2.5 were established.It was found that decreasing the rim width resulted in a lower mass flow rate of the leakage flow,and the pressure distributions from the leading edge to the trailing edge showed a linearly increasing trend.It was also found that if the inlet velocity was less than 1.5 m/s,the flow field in the passage far away from the suction side appeared as a stagnation zone.展开更多
The oxidation of Na4Fe(CN)6 complex by S2O8 2- anion was found to follow an outer-sphere electron transfer mechanism. We firstly carried out the reaction at pH=1. The specific rate constants of the reaction...The oxidation of Na4Fe(CN)6 complex by S2O8 2- anion was found to follow an outer-sphere electron transfer mechanism. We firstly carried out the reaction at pH=1. The specific rate constants of the reaction, kox, are (8.1± 0.07)×10-2 and (4.3±0.1)×10-2 mol-1?L?s-1 at μ=1.0 mol?L-1 NaClO4, T=298 K for pH=1 (0.1 mol?L-1 HClO4) and 8, respectively. The activation parameters, obtained by measuring the rate constants of oxidation 283—303 K, were ?H≠=(69.0±5.6) kJ?mol-1, ?S≠=(-0.34±0.041)×102 J?mol-1?K-1 at pH=1 and ?H≠= (41.3±5.5) kJ?mol-1, ?S≠=(-1.27±0.33)×102 J?mol-1?K-1 at pH=8, respectively. The cyclic voltammetry of Fe(CN)36 -/4- shows that the oxidation is a one-electron reversible redox process with E1/2 values of 0.55 and 0.46 V vs. normal hydrogen electrode at μ=1.0 mol?L-1 LiClO4, for pH=1 and pH=8 (Tris), respectively. The kinetic results were discussed on the basis of Marcus theory.展开更多
基金the Funds for International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.51120165002)the Key Project of Chinese National Programs for Fundamental Research and Development(Grant No.2007CB210107)are gratefully acknowledged.
文摘An experimental investigation of the tip flow characteristics between a gas turbine blade tip and the shroud was conducted by a pressure-test system and a particle image velocimetry(PIV)system.A three-times scaled profile of the GE-E3 blade with five film cooling holes was used as specimen.The effects on flow characteristics by the rim width and the groove depth of the squealer tip were revealed.The rim widths were(a)0.9%,(b)2.1%,and(c)3.0%of the axial chord,and the groove depths were(a)2.8%,(b)4.8%,and(c)10%of the blade span.Several pressure taps on the top plate above the blades were connected to pressure gauges.By a CCD camera the PIV system recorded the velocity field around the leading edge zone including the five cooling holes.The flow distributions both in the tip clearance and in the passage were revealed,and the influence of the inlet velocity was determined.In this work,the tip flow characteristics with and without film cooling were investigated.The effects of different global blowing ratios of M=0.5,1.0,1.3 and 2.5 were established.It was found that decreasing the rim width resulted in a lower mass flow rate of the leakage flow,and the pressure distributions from the leading edge to the trailing edge showed a linearly increasing trend.It was also found that if the inlet velocity was less than 1.5 m/s,the flow field in the passage far away from the suction side appeared as a stagnation zone.
基金Project supported by the National Natural Science Foundation of China (No. 20171010).
文摘The oxidation of Na4Fe(CN)6 complex by S2O8 2- anion was found to follow an outer-sphere electron transfer mechanism. We firstly carried out the reaction at pH=1. The specific rate constants of the reaction, kox, are (8.1± 0.07)×10-2 and (4.3±0.1)×10-2 mol-1?L?s-1 at μ=1.0 mol?L-1 NaClO4, T=298 K for pH=1 (0.1 mol?L-1 HClO4) and 8, respectively. The activation parameters, obtained by measuring the rate constants of oxidation 283—303 K, were ?H≠=(69.0±5.6) kJ?mol-1, ?S≠=(-0.34±0.041)×102 J?mol-1?K-1 at pH=1 and ?H≠= (41.3±5.5) kJ?mol-1, ?S≠=(-1.27±0.33)×102 J?mol-1?K-1 at pH=8, respectively. The cyclic voltammetry of Fe(CN)36 -/4- shows that the oxidation is a one-electron reversible redox process with E1/2 values of 0.55 and 0.46 V vs. normal hydrogen electrode at μ=1.0 mol?L-1 LiClO4, for pH=1 and pH=8 (Tris), respectively. The kinetic results were discussed on the basis of Marcus theory.
