Investigation Of Combustion Organization And Performance Of Tandem Type Turbine Based Combined Cycle Hyperburner

As an air breathing engine, turbine based combined cycle engine(TBCC) has gained great attentionin worldwide for it’s superior performance of broad flight envelop. Also TBCC can be used repeatedly and can take off and landing conveniently, which makes TBCC considered to be the most promisingly hypersonic airbreathing propulsion device at present. To meet the propulsion performance requirements in the broad operation range, the key technology of maintaining efficient and stable combustion in the hyperburner both in turbofan and ramjet modes should be solved, and the combustion performance of two modes throughout the flight envelop ought to be understand. In this paper the key combustion organization technology and the performance of TBCC hyperburner were researched with experimental and numerical simulation methods. The main study results are as follows:1.The hyperburner design solution was proposed on the basis of the flow characteristics in different operation modes. The hyperburner design principle is utilizing the core hot gas to prompt the bypass mixture ignition and flame spreading, which makes the whole hyperburner combustion effective and achieves the goal of low resistance and high efficiency combustion.An experimental platform was established, which provides the foundation for the components study and hyperburner combustion performance testing.2.The mixing technology considered two modes flow under large bypass to core velocity ratio was systematically research. The enhanced mixing structure was designed which was composed of tongue shape deflectors and a square-lobed-mixer carrying with baffles in front of the mixer peak. The effect of the square-lobed-mixer and deflector on mixing characteristics was studied.The results indicate that the mixing characteristics is excellent in the range of velocity ratio of VR=0.4~6 using the enhanced mixing scheme which is combined of discrete tongue shape deflectors fixed in flow channel and a square-lobed-mixer carrying with baffles in front of the mixer peak. This mixing structure enhances heat and mass transfer between turbo core flow and ram bypass flow by the streamwise vortices generating downstream the mixer, and mean while restrains the flow separation in the lobed mixer and near the cone.3.The technology of broadening the hyperburner lean ignition and blowout limits was studied under the flow conditions of T=450K~650K and Ma=0.1~0.4. An crescent evaporation tube flameholder was proposed on the basis of evaporation tube flameholder and film evaporation tube flameholder lean ignition and blowout limits research results.The experimental results show that the lean ignition and blowout performance of crescent evaporation tube flameholder is superior to the traditional evaporation flameholder, the reason of the crescent flameholder’s superior performance is that the crescent evaporation tube provides a stable dimension low-speed backflow zone along the tube length and the zone is not affected by the incoming flow mach number. The lean ignition and blowout equivalence ratio of the crescent evaporation tube flameholder was only 31% and 47% of the he traditional evaporation flameholder at the case of T=450K and Ma=0.4.4.The effect of fuel-air distribution on combustion performance experiments throughout entire flight envelope were carried out, and the injection scheme matching the variational hyperburner flow field was proposed. The results showed that fuel distributionis improved by staggered array atomizers in axial and circumferential direction, and the formation of a continuous curtain distribution is beneficial to high quality fuel-air mixtures formationthus is favorable to the combustion performance. To obtain the best combustion performance both in turbo and ram mode,the position of the main combustion zone fuel injection bars should be adjusted according to the flow structure at different engine modes.5.The hyperburner designing scheme was proposed based on the key technology resolution, which includea mixing chamber based on a square lobed mixer, a flameholder consists of an annular crescent evaporation premier stabilizer and radial V-gutters and a injection scheme which can meet the entire flight envelope requirements.The results show that,with this designing scheme, the hyperburner has reasonable flow field and outlet temperature distribution. The hyperburner has a high combustion efficiency and meets the goals of low resistance and high efficiency combustion.This thesis research results provide technical supports for the hyperburner design of tandem type turbine based combined cycle engine.