start-ver=1.4 cd-journal=joma no-vol=29 cd-vols= no-issue=3 article-no= start-page=639 end-page=647 dt-received= dt-revised= dt-accepted= dt-pub-year=2013 dt-pub=2013 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Supersonic Combustion Using a Stinger-Shaped Fuel Injector en-subtitle= kn-subtitle= en-abstract= kn-abstract= We developed a stinger-shaped injector (stinger injector) for supersonic combustors in cold-flow experiments. The stinger injector has a port geometry with a sharp leading edge in front of a streamwise slit. This injector produced higher jet penetration at a lower jet-tocrossflow momentum flux ratio (J) than a conventional circular injector. We applied the injector in a Mach 2.44 combustion test at a stagnation temperature of 2060 K. At a low fuel equivalence ratio (ƒ³) regime (i.e., low J regime), the injector produced 10% higher pressure thrust than the circular injector because of high jet penetration as expected from the coldflow experiments. Even at a moderate ƒ³ regime, the stinger injector produced higher pressure thrust than the circular injector. At moderate ƒ³, the stinger injector held the flame around the injector and generated a precombustion shock wave in front of the injector. The presence of the precombustion shock wave decreased the momentum flux of the crossflow air and diminished the advantage of the injector for jet penetration. The injector, however, produced higher pressure thrust because better flame-holding produced higher pressure around the injector. At a higher ƒ³ regime, the precombustion shock wave went upstream with both injectors. The far-upstream presence of a precombustion shock wave increased the turbulence in the crossflow and spread the fuel from both injectors. Thus, the difference in injector shape was insignificant for thrust performance en-copyright= kn-copyright= en-aut-name=KouchiToshinori en-aut-sei=Kouchi en-aut-mei=Toshinori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=MasuyaGoro en-aut-sei=Masuya en-aut-mei=Goro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=HiranoKohshi en-aut-sei=Hirano en-aut-mei=Kohshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=MatsuoAkiko en-aut-sei=Matsuo en-aut-mei=Akiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology kn-affil= affil-num=2 en-affil=Tohoku University kn-affil= affil-num=3 en-affil=Keio University kn-affil= affil-num=4 en-affil=Keio University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=28 cd-vols= no-issue=1 article-no= start-page=106 end-page=112 dt-received= dt-revised= dt-accepted= dt-pub-year=2012 dt-pub=2012 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Mechanism and Control of Combustion-Mode Transition in a Scramjet Engine en-subtitle= kn-subtitle= en-abstract= kn-abstract= A sidewall compression scramjet engine operated in two combustion modes under Mach 6 flight condition, weak- and intensive-combustion modes. The weak mode occurred below the overall fuel equivalence ratio (ƒ³) of around 0.4. Transition from the weak mode to the intensive mode occurred at ƒ³ ~ 0.4, accompanied by a sudden increase in thrust. Mechanisms of the transition were numerically investigated in this study. Our simulations captured the sudden increase in thrust at the mode transition. In the weak mode, combustion occurred in only a region near the topwall where an igniter was installed. The combustion region expanded toward the cowl with boundary-layer separation at the mode transition. Our simulations demonstrated that low ignition capability resulted in the weak mode. We demonstrated that the presence of additional igniters on the sidewalls improved the ignition capability and achieved the intensive mode in the entire ƒ³ range. en-copyright= kn-copyright= en-aut-name=KouchiToshinori en-aut-sei=Kouchi en-aut-mei=Toshinori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=MasuyaGoro en-aut-sei=Masuya en-aut-mei=Goro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=MitaniTohru en-aut-sei=Mitani en-aut-mei=Tohru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TomiokaSadatake en-aut-sei=Tomioka en-aut-mei=Sadatake kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=graduate school of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Tohoku University kn-affil= affil-num=3 en-affil=Japan Aerospace Exploration Agency kn-affil= affil-num=4 en-affil=Japan Aerospace Exploration Agency kn-affil= END