Recently,by combining a swirl flow with non-equilibrium condensation phenomena of condensate gas generated in a supersonic flow,a separating and extracting techniques of condensate gas have been developed.This techniq...Recently,by combining a swirl flow with non-equilibrium condensation phenomena of condensate gas generated in a supersonic flow,a separating and extracting techniques of condensate gas have been developed.This technique can reduce the size of the device and don't use chemicals.In the present study,by using a non-equilibrium condensation phenomenon of moist air occurred in the supersonic flow in the annular nozzle composed of an inher body and an outer nozzle with a swirl,the possibility of separation of the condensable gas and the effect of shape of nozzle inlet on the flow field were examined numerically.展开更多
Flow separation occurs over the compression comers generated by deflected control surfaces on hypersonic re-entry vehicles and in the inlet of scram jet engines. Configurations like a double wedge and double cone mode...Flow separation occurs over the compression comers generated by deflected control surfaces on hypersonic re-entry vehicles and in the inlet of scram jet engines. Configurations like a double wedge and double cone model are useful for studying the separated flow features. Flow fields around concave comers are relatively complicated and produce several classical viscous flow features depending on the combination of the first and second wedge or cone half apex angles. Particularly characteristic phenomena are mainly shock/boundary layer, shock/shock interaction, unsteady shear layers and non-linear shock oscillations. Although most of these basic gas dynamics characteristics are well known, it is not clear what happens at high enthalpy conditions. This paper reports a result of flow fields over a double wedge at a stagnation enthalpy of 4.8 MJ/kg. The experiment was carried out in a free piston shock tunnel at a nominal Mach number of 6.99. Schlieren and double exposure holographic interferometry were applied to visualize the flow field over the double wedge.展开更多
In some rocket nozzle flows, the existence of the transition from FSS to RSS and the occurrence of asymmetric flow are known in previous researches. As a result, the transition causes excessive side-loads that may dam...In some rocket nozzle flows, the existence of the transition from FSS to RSS and the occurrence of asymmetric flow are known in previous researches. As a result, the transition causes excessive side-loads that may damage the nozzle. Thus, it is important to investigate the method in order to control the asymmetric flow separation. In the present study, the relationship between the asymmetric separation and the rate of change of the pressure ratio with time was investigated from the point of view of the transition from FSS to RSS in the supersonic nozzle experimentally. Further, change of the flow separation by using step and cavity, and the possibility of the control was demonstrated. As a result, it was shown that the method using a cavity was effective for the control of the separation pattern.展开更多
In the present study, an ellipsoid reflector was designed and produced using silicon resin in order to generate and focus expansion wave in water for the purpose of a medical application. Across an expansion wave the ...In the present study, an ellipsoid reflector was designed and produced using silicon resin in order to generate and focus expansion wave in water for the purpose of a medical application. Across an expansion wave the static pressure, temperature and density decrease, as a result, negative pressure is given behind the expansion wave generated in the water, and then a tensile stress is induced. As an acoustic impedance of the silicon resin is almost similar to that of water, the interface of air-silicon resin would be regarded as the same with that of the air-water. A high voltage discharge was used as an energy source of underwater shock wave. When the underwater shock wave reflects on this interface, it is already clear that the shock wave converts to the expansion wave. The generation and focusing of the expansion wave were carried out and the phenomena were observed by flow visualization using a high-speed camera.展开更多
Control of supersonic flow fields with shock wave is important for some industrial fields. There are many studies for control of the supersonic flow fields using active or passive control. When non-equilibrium condens...Control of supersonic flow fields with shock wave is important for some industrial fields. There are many studies for control of the supersonic flow fields using active or passive control. When non-equilibrium condensation occurs in a supersonic flow field, the flow is affected by latent heat released. Many studies for the condensation have been conducted and the characteristics have been almost clarified. Further, it was found that non-equilibrium condensation can control the flow field. In these studies, the condensation occurs across the passage of the flow field and it causes the total pressure loss in the flow field. However, local occurrence of non-equilibrium condensation in the flow field may change the characteristics of total pressure loss compared with that by the condensation across the passage of the nozzle and there are few for researches of locally occurred non-equilibrium condensation in supersonic flow field. The purpose in the present study is to clarify the effect of local occurrence of non-equilibrium condensation on the transonic flow field in a nozzle with a circular bump. As a result, local occurrence of non-equilibrium condensation reduced the shock strength and total pressure loss in the transonic flow field by flowing the moist air from trailing edge of the circular bump to the mainstream.展开更多
In the previous researches, it is known that the swirl flow in circular pipe causes the temperature separation. Recently, it is shown that the temperature separation occurs in a vortex chamber when compressed air are ...In the previous researches, it is known that the swirl flow in circular pipe causes the temperature separation. Recently, it is shown that the temperature separation occurs in a vortex chamber when compressed air are pumped into this device from the periphery. Especially, in a cavity installed in the periphery of the chamber, the highest temperature was observed. Therefore, it is expected that this device can be used as a heat source in the engineering field. In recent researches, the mechanism of temperature separation in vortex chamber has been investigated by some researchers. However, there are few researches for the effect of diameter and volume of vortex chamber, height of central rod and position of cavity on the temperature separation. Further, no detailed physical explanation has been made for the temperature separation phenomena in the vortex chamber. In the present study, the effects of chamber configuration and position of the cavity on temperature separation in the vortex chamber were investigated experimentally.展开更多
文摘Recently,by combining a swirl flow with non-equilibrium condensation phenomena of condensate gas generated in a supersonic flow,a separating and extracting techniques of condensate gas have been developed.This technique can reduce the size of the device and don't use chemicals.In the present study,by using a non-equilibrium condensation phenomenon of moist air occurred in the supersonic flow in the annular nozzle composed of an inher body and an outer nozzle with a swirl,the possibility of separation of the condensable gas and the effect of shape of nozzle inlet on the flow field were examined numerically.
文摘Flow separation occurs over the compression comers generated by deflected control surfaces on hypersonic re-entry vehicles and in the inlet of scram jet engines. Configurations like a double wedge and double cone model are useful for studying the separated flow features. Flow fields around concave comers are relatively complicated and produce several classical viscous flow features depending on the combination of the first and second wedge or cone half apex angles. Particularly characteristic phenomena are mainly shock/boundary layer, shock/shock interaction, unsteady shear layers and non-linear shock oscillations. Although most of these basic gas dynamics characteristics are well known, it is not clear what happens at high enthalpy conditions. This paper reports a result of flow fields over a double wedge at a stagnation enthalpy of 4.8 MJ/kg. The experiment was carried out in a free piston shock tunnel at a nominal Mach number of 6.99. Schlieren and double exposure holographic interferometry were applied to visualize the flow field over the double wedge.
文摘In some rocket nozzle flows, the existence of the transition from FSS to RSS and the occurrence of asymmetric flow are known in previous researches. As a result, the transition causes excessive side-loads that may damage the nozzle. Thus, it is important to investigate the method in order to control the asymmetric flow separation. In the present study, the relationship between the asymmetric separation and the rate of change of the pressure ratio with time was investigated from the point of view of the transition from FSS to RSS in the supersonic nozzle experimentally. Further, change of the flow separation by using step and cavity, and the possibility of the control was demonstrated. As a result, it was shown that the method using a cavity was effective for the control of the separation pattern.
基金supported by a research grant from Harada Memorial Foundationsupported by Saga University Dean‘s Grant 2012 For Promising Young Researchers
文摘In the present study, an ellipsoid reflector was designed and produced using silicon resin in order to generate and focus expansion wave in water for the purpose of a medical application. Across an expansion wave the static pressure, temperature and density decrease, as a result, negative pressure is given behind the expansion wave generated in the water, and then a tensile stress is induced. As an acoustic impedance of the silicon resin is almost similar to that of water, the interface of air-silicon resin would be regarded as the same with that of the air-water. A high voltage discharge was used as an energy source of underwater shock wave. When the underwater shock wave reflects on this interface, it is already clear that the shock wave converts to the expansion wave. The generation and focusing of the expansion wave were carried out and the phenomena were observed by flow visualization using a high-speed camera.
文摘Control of supersonic flow fields with shock wave is important for some industrial fields. There are many studies for control of the supersonic flow fields using active or passive control. When non-equilibrium condensation occurs in a supersonic flow field, the flow is affected by latent heat released. Many studies for the condensation have been conducted and the characteristics have been almost clarified. Further, it was found that non-equilibrium condensation can control the flow field. In these studies, the condensation occurs across the passage of the flow field and it causes the total pressure loss in the flow field. However, local occurrence of non-equilibrium condensation in the flow field may change the characteristics of total pressure loss compared with that by the condensation across the passage of the nozzle and there are few for researches of locally occurred non-equilibrium condensation in supersonic flow field. The purpose in the present study is to clarify the effect of local occurrence of non-equilibrium condensation on the transonic flow field in a nozzle with a circular bump. As a result, local occurrence of non-equilibrium condensation reduced the shock strength and total pressure loss in the transonic flow field by flowing the moist air from trailing edge of the circular bump to the mainstream.
文摘In the previous researches, it is known that the swirl flow in circular pipe causes the temperature separation. Recently, it is shown that the temperature separation occurs in a vortex chamber when compressed air are pumped into this device from the periphery. Especially, in a cavity installed in the periphery of the chamber, the highest temperature was observed. Therefore, it is expected that this device can be used as a heat source in the engineering field. In recent researches, the mechanism of temperature separation in vortex chamber has been investigated by some researchers. However, there are few researches for the effect of diameter and volume of vortex chamber, height of central rod and position of cavity on the temperature separation. Further, no detailed physical explanation has been made for the temperature separation phenomena in the vortex chamber. In the present study, the effects of chamber configuration and position of the cavity on temperature separation in the vortex chamber were investigated experimentally.
