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In response to some problems that occurred when a steel mill in China transitioned to automatic steelmaking, a high-Mach-number oxygen lance was designed and forged. The designed oxygen pressure was 1.01 MPa; at this high oxygen pressure, the Mach number of the nozzle outlet could reach 2.15. A three-dimensional two-phase flow model was established by numerical simulation, and the jet characteristics of the high-Mach-number oxygen-lance nozzle at different oxygen-supply pressures and the impact of the jet on the melting pool were analyzed and studied. The jet was found to be most stable in the oxygen-supply-pressure range 0.9 to 1.01 MPa. Considering the impact depth, impact area, velocity distribution in the molten pool, and mixing time, a combined top- and bottom-blowing process could optimize the mixing effect of the nozzle on the molten pool. Application of the nozzle in industrial practice greatly improved the stability, quality, and efficiency of smelting and lengthened the life of the oxygen-lance nozzle by 100 furnaces. [ABSTRACT FROM AUTHOR]

The 0.6 m continuous transonic wind tunnel of China Aerodynamics Research and Development Center (CARDC) is a circling wind tunnel using variable density dry air as working medium. Depending on the general performance calibration, the flow quality of the wind tunnel is tested in different conditions by parameters optimization of the walls (slotted or perforated), acoustics treatments on the compressor tailor and the forth corner, re-adjusting the expansion angles of the test section walls and the re-entry slots, controlling the semi-flexible nozzle, the second throat and the plenum chamber pumping system. Testing results of the flow quality indicate that: The total pressure control precision in settling chamber is better than 0.1% and the Mach number control precision in test section is better than 0.001; The pressure fluctuating coefficient ΔCp of the core flow in transonic test section is below 0.8%; The average flow deflection was better than 0.1°; Fluctuation of Mach number distribution and the standard model testing precision have met the requirements. The flow quality calibration demonstrated fully feasibility of the wind tunnel design scheme. The experience of 0.6 m wind tunnel provides a reference for the scheme design of China’s large continuous transonic wind tunnel and the quality assurance of international advanced flow field. [ABSTRACT FROM AUTHOR]

Rocket based combined cycle (RBCC) engine is regarded as one of the most efficient propulsion systems for reusable space transportation vehicles and hypersonic cruise vehicles. It can perform excellently over a very broad range of Mach numbers and flight altitudes through multi-mode operations by effectively integrating high thrust-to-weight ratio of the rocket engine and high specific impulse of the airbreathing engine. The RBCC inlet, commonly operating in an extremely wide flight speed range covering static, subsonic, transonic, supersonic, and hypersonic, plays a vital role in the RBCC propulsion system and flight vehicles. This paper presents a comprehensive and systematical review of the research progress on the inlets for RBCC engines in different countries and different historical periods. A number of key technical and scientific issues specially concerning RBCC inlets are sorted out, including the wide range RBCC inlet design and optimization, inlet/embedded rocket/combustor matching and control, dynamic operation, etc. Several typical RBCC inlet applications and the corresponding research are discussed, including the Strutjet inlet, A5 inlet, GTX inlet, and the Astrox's inlet in the U.S., the RBCC inlet in JAXA, and a sidewall compression RBCC inlet in China. Finally, experience gained and some recommendations are summarized for future research of the RBCC inlet. [ABSTRACT FROM AUTHOR]

Achieving efficient fuel-air mixing is a crucial problem for the design of scramjet engines. Due to the very short residence time of the fuel within the scramjet combustor for typical flight conditions, an efficient injection strategy with high penetration depth and rapid mixing is required. For this reason, many mixing augmentation devices have been proposed and investigated, namely wall injection, struts, ramps, cavities, vortex generators and new configurations developed in China. In this survey, their mixing augmentation mechanisms are analyzed and the numerical and experimental studies are described which have been performed for the assessment of their mixing effectiveness. Some novel insights are provided to further the development of large-scale scramjet engines at increased flight Mach number. The need for additional research based on improved numerical approaches and experimental facilities is stressed. [ABSTRACT FROM AUTHOR]