Showing papers in "Journal of Rocket Propulsion in 2013"

Influence of thermodynamics effect on inducer rotating cavitation under low temperature condition

Abstract: Inducer is a key component of liquid rocket propulsion system to improve the performance of turbopump.It is well-known that rotating cavitation is harmful to turbopump,and even causes the launch failure of a rocket.Cavitation in cryogenic fluids can produce much latent heat,and has a thermodynamic effect because of thermal imbalance around the cavity.A numerical analysis of cryogenic fluids rotating cavitation in 2D blade cascade in inducer is performed with a mixture model based on Rayleigh-Plesset equation with the thermodynamic effect considered.The results indicate that the inlet pressure will decrease when take into account the thermodynamic effect.Changes in the temperature of liquid hydrogen effect on the super-synchronous rotating cavitation are not obvious, but on the sub-synchronous rotating cavitation are significant

Influence of welding parameters of pulse TIG on weld microstructure and mechanical property of aluminum alloys

Abstract: Two welding tests of 1.5 mm 5A06 aluminum alloy plate welded with 1.5 mm L3 aluminum plate and 3 mm 5A06 aluminum alloy-plate with 3 mm 5A06 aluminum alloy plate were conducted by welding method of pulse changing polarity TIG.The influence rule of pulse frequency,basic value current and duty ratio on weld microstructure and mechanical property was researched when other two conditions were unchanged.The research indicates when pulse frequency is 100 Hz,basic value current is 10%～33% of peak value current and duty ratio is 50%～66%,the welded joint possesses good microstructure and mechanical property.

Thinking about RBCC propulsion system

Abstract: The development course and trend for the rocket based combined cycle(RBCC) propulsion system are reviewed.The velocity,altitude and other basic characteristics of the RBCC propulsion system are analyzed.A suggestion that the development of the RBCC propulsion system should be devoted to improving the function and performance of LRE and ramjet is proposed.It is found that the integrated design of the RBCC propulsion system and aircraft should be enhanced;the sharing of air intake duct,combustor,tailpipe nozzle and fuel supply system might be considered in the integrated design;the study of key and basic technologies of RBCC propulsion system must be carried out according to the specific aircraft project.The development of high-speed aircraft propulsion system running in the near-earth space should be conducted first to tackle the key technology for the second stage of two-stage-to-orbit propulsion systems.

Numerical study on effect of arc leading edge and trailing edge of cavity on flow field

Abstract: The two-dimensional simulation for the supersonic flow field of concave-cavity architectures with different radius arc leading and trailing edges was carried out based on k-ω SST modelThe corresponding flow field feature parameters were obtainedThe simulation results show that,compared with the right angle leading and trailing edges,the shock wave was strengthened near the trailing edges when using the arc edgesBy contrast,cavities with different arc radius were considered when the velocity,temperature and vorticity were calculatedIt demonstrates that,with the increase of arc radius,the velocity inside the cavity increases,and temperature and vorticity magnitudes appears a decline trendAs viewed from flame stabilization and combustion-supporting,the pressure increase at the upper end of back wall can promote the mass exchange and at the same time,can lower the temperature in recirculation zoneA proper limit of the arc radius is proposed in overall consideration of flame stabilization and combustion-supporting effect of concave-cavity

System configuration of LOX/methane rocket engine with dual-bell nozzle

Abstract: A system scheme of LOX/methane rocket engine with dual-bell nozzle is presented based on altitude compensation features and development status of dual-bell nozzle.The aero ratio of basic arc section and stretching section of the dual-bell nozzle was optimized.Its performance was compared with other system schemes.The result shows that,as for the core engine launched on ground,the application of the dual-bell nozzle is an effective way of improving the engine comprehensive specific impulse and payload of launch vehicle.

Study on ceramic blind hole processing method based on laser rotation cutting

Abstract: The basic principle of laser drilling is introduced in this paper.The influence of laser energy,defocusing amount and trajectory during the ceramic blind hole processing on hole shape and surface quality was analyzed and verified in experiments.A general law is given.The rational process parameters were determined according to the test results.The rotation cutting was adopted to make the blind hole on Cf/SiC,whose diameter is 1 mm,depth is 1.1 mm and taper is less than 15°.

Current status and development trend of space propulsion technologies abroad

Abstract: Space propulsion technologies usually can be divided into four types: conventional chemical propulsion, electric propulsion, micro propulsion and novel propulsion. The conventional chemical propulsion is the mostly-used propulsion technology, whose performance is being improved continuously. The electric propulsion is widely used in various satellite and deep space probes, whose advantages and reliability have been proved, and whose power range is being expanded. Vigorous development of micro satellites calls for active demands of micro propulsion featured by micro thrust,low weight and low power. The novel propulsion technologies, such as green chemical propulsion, solar propulsion, nuclear propulsion, are fast-developed or flight-testing in space. The application and research status of space propulsion technology used in foreign satellites and deep space probes are reviewed, and the development trends are analyzed. Several suggestions are given on the development of domestic space propulsion technologies.

Design and experiment research of GH_2/GO_2 vortex-cooling transparent combustion chamber

Abstract: Vortex-cooling is a new thrust chamber cooling method.This technology can simplify the thrust chamber structure,reduce cost and increase system reliability.Based on the research findings of foreign countries,the vortex-cooling technology was analyzed theoretically,the structure of thrust chamber was designed,quartz glass was adopted to make the cylindrical part of the chamber, and the flame images were recorded by a high-speed camera.The results show that the design scheme of GH_2/GO_2 vortex-cooling transparent combustion chamber is feasible.The combustion zone occupied 55%~60%of the combustion chamber designed with this scheme in the stable period of combustion.

Analysis on thermodynamic cycle characteristics of synergistic air-breathing rocket engine

Abstract: The basic thermodynamic process of synergistic air-breathing rocket engine(SABRE) is analyzed with the first law of thermodynamics methodThe ideal cycle work and thermal efficiency expressions in both air-breathing mode and rocket mode were obtainedFurthermore,several characteristic parameters which affect the performance of the ideal thermodynamic cycles were determinedResults reveal that the pressune ratio of the compressor and cycle temperature ratio are the key parameters affecting the ideal thermodynamic cycle performance when SABRE core engine in air-breathing mode works in Brayton cycle,and the decompression ratio in the nozzle and exhaust velocity at nozzle outlet are the important parameters affecting the ideal thermodynamic cycle performance when the rocket engine cycle is adopted for SABREThe helium energy transmission between all the cycle sub-systems is realized only by heat exchangers in the engine,but has no effects on ideal cycle work and thermal efficiency of SABRE

Combustion phenomena of kerosene and UDMH droplets in supercritical environment

Abstract: The piston driver experimental system is used to perform a preliminary study on evaporation and combustion phenomena of kerosene and UDMH single fuel droplet in supercritical environment. The result shows that the kerosene or UDMH droplet will be vaporized in supercritical environment, it does not matter whether it is in liquid state or gel state. The spontaneous combustion phenomenon will happen when kerosene and UDMH droplet in the air supercritical environment. The spontaneous combustion appears in multi-dot simultaneous ignition at different position. It strongly resembles forest fire and lasts for along time. The combustion can be divided into four successive phases: evaporation, ignition, combustion prophase and combustion anaphase.

Research on transient time-domain data synthesis of shock response spectrum

Abstract: Shaker is adopted to simulate the shock environment in the test for parts of the liquid rocket engines. In the test, the shock time-domain waveform of shock response spectrum(SRS) is composed of sine wave, compound wavelet and Chirp wave. The sine wave composed shock spectrum is often used in China to perform the shock environment test of the liquid rocket engines.The shock time-domain waveform of SRS is composited according to the data extracted from shock time-domain signal in the liquid rocket engines testing. The calculated result proves that the algorithm is effective, and the composited shock time-domain data can meet the accuracy requirement of the reference shock response spectrum.

Experimental study on methane heat transfer test system

Abstract: A methane heat transfer test system was built to investigate the methane heat transfer and flow resistance characters in the coolant channel of thrust chamber in liquid rocket engine.Five supercritical hot fire tests and two subcritical hot fire tests for methane heat transfer study were performed in trust chamber extrusion heat test.The conditions of supercritical methane heat transfer tests are combustion chamber pressure of 5.5~7.5 MPa,O/H mixture ratio of about 6.8,methane temperature of 128~230 K,methane coolant mass flow of 5~7 kg/s,methane coolant inlet pressure of 8.3~11.7 MPa.The conditions of subcritical methane heat transfer tests are combustion chamber pressure of about 4 MPa,O/H mixture ratio of about 2.8,methane temperature of 128~189 K,methane coolant mass flow of about 2.9 kg/s,coolant inlet pressure of 3~3.5 MPa.The heat transfer and flow resistance characters of liquid methane in trust chamber cooling channels were obtained in supercritical and subcritical pressure states by experimental study.

Numerical study on igniter performance of liquid ramjet combustor

Abstract: Based on gas dynamics and computational fluid mechanics, the numerical simulation of the steady-state flow field of igniter working independently in the liquid ramjet combustor was conducted with CFD-ACE+ software. Influences of chamber pressure in igniter, ignition gas flow pipe's inner diameter and its structure on the flame ignition performance were analyzed on the basis of test validation. The analyzed result shows: under the conditions of constant igniter temperature and gas flow rate, lower chamber pressure in igniter is more beneficial to ignition if pipe expansion ratio remains unchanged; if the pipe inner diameter is increased within limits, the ignition performance of flame can be improved; if gas flows through the straight pipe it has less flow loss; the higher the gas jet flow velocity at the outlet is, the bigger the penetration depth appears; the elbow in the pipe hasmore influence on flame property, but the elbow angle has less influence.

Solution of transient flow in propellant pipelines by Chebyshev spectral collocation method

Abstract: A new fast and efficient algorithm,Chebyshev spectral collocation method(CSCM),is introduced to solve the hyperbolic partial differential equations governing the transient flow in the propellant pipelines.The numerical oscillation caused by solving the discontinuous or big gradient change was effectively eliminated by adding the super spectral viscosity term into transient flow control equations.Taking a uniform cross section pipe connecting the tank and valve as an example,the water hammer phenomenon,which appears when the pipe is closed,is calculated with the method. The simulation result under the corresponding water hammer pressure is offered and compared with the results obtained respectively from the characteristics method and finite element method.The feasibility of solving the transient flow in the propellant pipelines by CSCM is demonstrated.

Investigation on aerodynamic and combustion characteristics of an evaporating flame-holder

Abstract: To realize reliable ignition,flame stabilization and effective combustion of a ramjet engine under the condition of low-temperature and high-velocity incoming flow,numerical analysis of cold-state and combustion flow fields for an evaporating flame-holder was completed,and contrastive analysis with the V-gutter flame-holder was performed.The results show that,in a given scope,with the increase of inlet velocity,the total pressure recovery coefficient and retention time are reduced obviously,and recirculation zone length,recirculation ratio and combustion efficiency change a little.Compared to the V-gutter flame-holder,the recirculation ratio is reduced more significantly,and the total pressure recovery coefficient,recirculation zone length,and retention time are decreased a little bit.Recirculation zone happens in downriver of evaporating flame-holder,and is not interfered by main-flow.The flame-holder can work at the best fuel-air mass ratio by local fuel supply and adapt to low-temperature high-velocity inlet environment.