Structural Research Of The Propellant Tank Aft Dome Transmitting Engine Thrust

In China,the traditional engine transmission structure of the Long March series of launch vehicle is not directly connected to the aft dome of the propellant tank,but the engine thrust is transmitted to the docking surface of the section of launch vehicle through engine frame.In contrast,the structural scheme of the propellant tank aft dome transmitting engine thrust can fully utilize the structural bearing capacity of the aft dome,and it is of great significance to realize the goal of lightweight,compact and efficient configuration of new future launch vehicle.At present,there are currently few literatures discussing the design principles of the aft dome transmitting engine thrust and guidance for it.This paper systematically studies the structure of aft dome transmitting engine thrust.Firstly,the finite element method(FEM)is used to analyze the ellipsoid and conical dome transmitting engine thrust of the 3.35 m diameter tank,including the law of stress and deformation distribution and thrust bearing capacity of the aft dome within a certain range of internal pressure,thrust radius,ellipsoid modulus and the half cone angle.Secondly,the feasibility and specific technical scheme of the actual engineering application of the aft dome transmitting engine thrust are studied,and the following conclusions are drawn:(1)In the launch vehicle with a diameter of 3.35 m,the aft dome transmitting engine thrust is strengthened by two ways: local thickening and reinforcement of the aft dome.The result shows that both ways can significantly improve the bearing capacity of(2)In the launch vehicle with a diameter of 3.35 m,a single engine with a ground thrust of 1200 kN is installed,and the thrust is transmitted through the aft dome.The result shows that the aft dome transmitting engine thrust is superior to the aft dome without transmitting engine thrust in terms of weight and height of the relevant structure(including frame,rear transition section,tail section,etc.).(3)In the launch vehicle with a diameter of 3.35 m,a single engine with a mass of 3000 kg is installed,which is connected to the aft dome through a small engine frame.The result shows that the aft dome connecting the small engine frame and engine can adapt to the horizontal and vertical state of launch vehicle in terms of stress and deformation.(4)In the launch vehicle with a diameter of 3.35 m,the weld strength of the tailor-welded aft dome transmitting engine thrust is compensated by thickening the weld.The result shows that the bearing capacity of the tailor-welded aft dome with thickening the weld has less difference with the integral aft dome,and is slightly larger than the integral aft dome.(5)In the launch vehicle with a diameter of 5m,a single engine with a vacuum thrust of 1400 kN is installed,and the thrust is transmitted through the aft dome.The result verifies that the feasibility of the ellipsoidal and conical aft dome transmitting engine thrust in the launch vehicle with a diameter of 5m under the internal pressure of 0.08MPa~0.33 MPa.