空中加油吊仓多采用"涵道式冲压空气涡轮"(Ducted Ram Air Turbine,以下简称DRAT)作为动力装置。空气涡轮性能的优劣直接影响DRAT的工作性能。为了对吊仓飞行高度以及飞行表速对空气涡轮性能影响进行研究,找到减少涡轮流动损...空中加油吊仓多采用"涵道式冲压空气涡轮"(Ducted Ram Air Turbine,以下简称DRAT)作为动力装置。空气涡轮性能的优劣直接影响DRAT的工作性能。为了对吊仓飞行高度以及飞行表速对空气涡轮性能影响进行研究,找到减少涡轮流动损失,提高系统的输出功率和效率的方法。采用NUMECA软件对涡轮流动进行叶轮机械数值仿真,对涡轮飞行包线内性能变化进行分析,得到了涡轮在飞行包线内的最小功率点和对应的最小功率,并通过对空气涡轮性能分析,建立一套关于空气涡轮性能的可行和实用的数值仿真方法。展开更多
The recent technological developments being applied to Tesla like turbines for converting fluid energy into mechanical （axis） energy often lead to non-frequently used models. Given a disk shaped machine rotating aro...The recent technological developments being applied to Tesla like turbines for converting fluid energy into mechanical （axis） energy often lead to non-frequently used models. Given a disk shaped machine rotating around its own symmetry axis, part of the machine energy is transferred to the fluid itself, pushing it to the disk periphery. This way the farther the exhaust orifice is from the disk outside contour, the larger will be the pressure loss experienced by the system. This work studies the overall energy balance and momentum exchange between fluid and machine. Simple calculation shows that for total pressure gradients above two bar the machines become inefficient for having tangential velocity whose intensity is 50% higher than the intensity of the jet velocity prior to the interaction. For values of the pressure gradient above 5.7 bar, the machine peripheral velocity is equal to the incident jet velocity. In this case it is not possible to deliver power under permanent regime. Finally it is shown that when the feeding pressure of an impulse turbine is enough for more than one stage, then one should use this option to obtain thermal efficiencies similar to those of reaction machines. The jet of fluid to move a Tesla like turbine should enter the unit as close as possible to the direction tangential to the movement, （i.e., normal to the radius at the considered position）. This fluid should leave the machine right after interacting with it. Any permanence of the fluid after transferring its momentum to the machine can be extremely prejudicial to the system behavior.展开更多
Oscillating water column （OWC） based wave energy plants have been designed with several types of bidirectional turbines for converting pneumatic power to shaft power. Impulse turbines with linked guide vanes and fix...Oscillating water column （OWC） based wave energy plants have been designed with several types of bidirectional turbines for converting pneumatic power to shaft power. Impulse turbines with linked guide vanes and fixed guide vanes have been tested at the Indian Wave Energy plant. This was after initial experimentation with Well＇s turbines. In contrast to the Well＇s turbine which has a linear damping characteristic, impulse turbines have non-linear damping. This has an important effect in the overall energy conversion from wave to wire. Optimizing the wave energy plant requires a turbine with linear damping and good efficiency over a broad range of flow coefficient. This work describes how such a design can be made using fixed guide vane impulse turbines. The Indian Wave Energy plant is used as a case study.展开更多
文摘空中加油吊仓多采用"涵道式冲压空气涡轮"(Ducted Ram Air Turbine,以下简称DRAT)作为动力装置。空气涡轮性能的优劣直接影响DRAT的工作性能。为了对吊仓飞行高度以及飞行表速对空气涡轮性能影响进行研究,找到减少涡轮流动损失,提高系统的输出功率和效率的方法。采用NUMECA软件对涡轮流动进行叶轮机械数值仿真,对涡轮飞行包线内性能变化进行分析,得到了涡轮在飞行包线内的最小功率点和对应的最小功率,并通过对空气涡轮性能分析,建立一套关于空气涡轮性能的可行和实用的数值仿真方法。
文摘The recent technological developments being applied to Tesla like turbines for converting fluid energy into mechanical （axis） energy often lead to non-frequently used models. Given a disk shaped machine rotating around its own symmetry axis, part of the machine energy is transferred to the fluid itself, pushing it to the disk periphery. This way the farther the exhaust orifice is from the disk outside contour, the larger will be the pressure loss experienced by the system. This work studies the overall energy balance and momentum exchange between fluid and machine. Simple calculation shows that for total pressure gradients above two bar the machines become inefficient for having tangential velocity whose intensity is 50% higher than the intensity of the jet velocity prior to the interaction. For values of the pressure gradient above 5.7 bar, the machine peripheral velocity is equal to the incident jet velocity. In this case it is not possible to deliver power under permanent regime. Finally it is shown that when the feeding pressure of an impulse turbine is enough for more than one stage, then one should use this option to obtain thermal efficiencies similar to those of reaction machines. The jet of fluid to move a Tesla like turbine should enter the unit as close as possible to the direction tangential to the movement, （i.e., normal to the radius at the considered position）. This fluid should leave the machine right after interacting with it. Any permanence of the fluid after transferring its momentum to the machine can be extremely prejudicial to the system behavior.
文摘Oscillating water column （OWC） based wave energy plants have been designed with several types of bidirectional turbines for converting pneumatic power to shaft power. Impulse turbines with linked guide vanes and fixed guide vanes have been tested at the Indian Wave Energy plant. This was after initial experimentation with Well＇s turbines. In contrast to the Well＇s turbine which has a linear damping characteristic, impulse turbines have non-linear damping. This has an important effect in the overall energy conversion from wave to wire. Optimizing the wave energy plant requires a turbine with linear damping and good efficiency over a broad range of flow coefficient. This work describes how such a design can be made using fixed guide vane impulse turbines. The Indian Wave Energy plant is used as a case study.
