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Using an airplane for a long range can damage bodies of airplanes. In order to solve this problem, saving flight time is the most effective. However, most of modern airplanes flight at subsonic: slower than speed of sound. When airplanes fight supersonic: faster than speed of sound, people on the ground are force to hear detonating sound which is not observed at subsonic flight. Our team are doing research on how to reduce this noise to develop next generation supersonic transports. Besides, we undertake the joint study with JAXA(Japan Aerospace Exploration Agency).
Sonic Boom
Fig.1 Sonic Boom |
When air planes flight at supersonic, shockwaves, expansion waves and other disturbances are induced. These are integrated in contagious process and the detonative sounds are observed on the ground.
This phenomenon is called sonic boom. Because of the noise produced by sonic boom, supersonic flight is forbidden on the land.
Therefore, reducing this noise is imperative to develop next generation supersonic transports.
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Experiment with Ballistic Range
Fig.2 Ballistic Range |
Our research develops the low boom aircraft by changing its shape. The study evaluates near filed pressure of super sonic free flight models not only by CFD but also by experiments which called ballistic range. The ballistic range can measure near field pressure without effecting stings. The availability of this equipment is limited in Japan. Thus, Our lab impliment research corporated with JAXA.
JAXA APG.
Sonic Boom reduction with staged aft body
Fig.3 Sonic Boom reduction with staged aft body
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From our research, it is indicated that attaching some steps to the model by changing its cross-sectional area in rear section has an effect on reducing sonic boom. Measuring near field pressure around supersonic free flight model by ballistic range is good for measuring flow around the model (especially flow of back of model) because a sting which is used in wind tunnel experiment is not needed.
Using this characteristic, we could demonstrate the reduction of rear sonic boom by experiments.
