The three-dimensional （3D） reacting flow in a staged supersonic combustor is examined numerically. In order to obtain the optimum stream-wise vortices, a swept ramp injector is chosen as the second-stage wall inject...The three-dimensional （3D） reacting flow in a staged supersonic combustor is examined numerically. In order to obtain the optimum stream-wise vortices, a swept ramp injector is chosen as the second-stage wall injection combined with the first-stage central strut injection. The performance of the two-staged injection is compared with that of a one-staged injection, while the strut is kept installed in both cases. The two-staged injections can make full use of the residual oxygen near the wall and release more heat. The second-stage injection further downstream avoids the strong shock waves in the isolator and results in a rising wall pressure and good burning effects after the wall injection. Therefore, it allows more fuel to be injected into the supersonic combustor without causing thermal choking. Parallel injection from the second-stage swept ramp shows low total pressure loss and the best burning efficiency, compared with the other injection angles.展开更多
Electromagnetic levitation of electrically conductive droplets by alternating magnetic fields is Sa technique used to measure the physical properties of liquid metallic alloys such as surface tension,viscosity,heat ca...Electromagnetic levitation of electrically conductive droplets by alternating magnetic fields is Sa technique used to measure the physical properties of liquid metallic alloys such as surface tension,viscosity,heat capacity.Experiments can be conducted in microgravity,to reduce electromagnetic stirring and shaping of the droplet.The inductor of the EML is composed of a single inductor which two types of voltage are imposed.This type of electrical installation generates a field to center the metallic droplet and another field to heat and excite it.We use a commercial code join to a homemade code to compute flows generated by inducting voltages recorded in the sounding rocket TEXUS-EML-2(Feb2008).In this flight,two samples(Cu75Co25 at%and A168,5Ni31,5 at%)of 8 mm diameter have been processed.展开更多
The TanDEM-X mission is a scientific and commercial Earth observation mission comprising two satellites flying in close formation. The formation maintenance can be advantageously performed by an onboard autonomous sys...The TanDEM-X mission is a scientific and commercial Earth observation mission comprising two satellites flying in close formation. The formation maintenance can be advantageously performed by an onboard autonomous system, which reduces the operational efforts, provides a shorter reaction time in case of contingencies and increases the control performance. The TanDEM-X Autonomous Formation Flying （TAFF） system has been developed for this purpose and is intended to replace the ground-based formation keeping activities during routine operations. TAFF has been activated for the first time in October 2010 for commissioning, during which the autonomous usage of thrusters was prohibited. Afterwards, a closed-loop campaign was successfully conducted in March 2011, demonstrating the capability of TAFF to maintain autonomously the formation. After a brief technical description of the system, the paper presents the key results gained during the commissioning phase and the closed-loop campaign,展开更多
基金National Natural Science Foundation of China(50306011)the German Research Foundation (DFG) (GRK1095/1)
文摘The three-dimensional （3D） reacting flow in a staged supersonic combustor is examined numerically. In order to obtain the optimum stream-wise vortices, a swept ramp injector is chosen as the second-stage wall injection combined with the first-stage central strut injection. The performance of the two-staged injection is compared with that of a one-staged injection, while the strut is kept installed in both cases. The two-staged injections can make full use of the residual oxygen near the wall and release more heat. The second-stage injection further downstream avoids the strong shock waves in the isolator and results in a rising wall pressure and good burning effects after the wall injection. Therefore, it allows more fuel to be injected into the supersonic combustor without causing thermal choking. Parallel injection from the second-stage swept ramp shows low total pressure loss and the best burning efficiency, compared with the other injection angles.
基金Item Sponsored by ESA (contract no.:MAP AO 099 022) EC under PI-IMPRESS (contract no.:NMP3-CT-2004-500635) CNES under Material Sciences Program
文摘Electromagnetic levitation of electrically conductive droplets by alternating magnetic fields is Sa technique used to measure the physical properties of liquid metallic alloys such as surface tension,viscosity,heat capacity.Experiments can be conducted in microgravity,to reduce electromagnetic stirring and shaping of the droplet.The inductor of the EML is composed of a single inductor which two types of voltage are imposed.This type of electrical installation generates a field to center the metallic droplet and another field to heat and excite it.We use a commercial code join to a homemade code to compute flows generated by inducting voltages recorded in the sounding rocket TEXUS-EML-2(Feb2008).In this flight,two samples(Cu75Co25 at%and A168,5Ni31,5 at%)of 8 mm diameter have been processed.
文摘The TanDEM-X mission is a scientific and commercial Earth observation mission comprising two satellites flying in close formation. The formation maintenance can be advantageously performed by an onboard autonomous system, which reduces the operational efforts, provides a shorter reaction time in case of contingencies and increases the control performance. The TanDEM-X Autonomous Formation Flying （TAFF） system has been developed for this purpose and is intended to replace the ground-based formation keeping activities during routine operations. TAFF has been activated for the first time in October 2010 for commissioning, during which the autonomous usage of thrusters was prohibited. Afterwards, a closed-loop campaign was successfully conducted in March 2011, demonstrating the capability of TAFF to maintain autonomously the formation. After a brief technical description of the system, the paper presents the key results gained during the commissioning phase and the closed-loop campaign,
