Fuel Sloshing Under Negative G And The Flight Attitude And Strength At Launching Of A UAV

With the development of science and technology, research on both military UAVs and civil UAVs become more and more popular because of their huge advantages. This thesis researches several mechanical problems of an UAV when launched by a rocket booster.This thesis simulates fuel sloshing under negative G, when UAV changes flight status, such as, from climbing to horizontal flight or accelerate decline, fuel in fuel tank will slosh and mix with air, which may lead to engine flameout. Simulates fuel sloshing in UAV common fuel tank and anti negative G fuel tank under negative G with SPH method, takes the amount of liquid into consideration. It is found that anti negative G fuel tank can avoid engine flameout.When controlling an UAV, the launch process is considered one of the most difficult works. On the on hand, in order to launching placidly, the resultant of rocket thrust, engine thrust and gravity should go through UAV’s center of gravity. On the other hand, because of the concentrated force, rocket thrust is large, the rocket thrust flame must satisfy the intensity and rigidity. This thesis simulates the UAV launch process by rocket booster with finite element method. Considers the attitude angle which influenced by deviation of rocket thrust direction and UAV’s center of gravity. Provides reference for practical application. Checking the intensity and rigidity of rocket thrust flame under static load and dynamic load with finite element method. It is found that connection defect has an enormous effect on intensity and rigidity.Contents and results of this thesis have certain reference significance for the development and application of UAV.