Based on the typical mission requirement of near space aircraft. A performance analysis model of high-speed aircraft/combined power integration is established. Taking the Deeply Precooled Combined Cycle Engine as the evaluation object, evaluates the ability of the power to complete typical missions, and studies the effects of different climbing modes, different wing loads and different takeoff weights on the aircraft. The important performance parameters of high-speed aircraft and engine in the flight profile are obtained. The research results show that the Deeply Precooled Combined Cycle Engine is suitable for completing long-range missions. If the mission purpose is to save fuel, the lower dynamic pressure climbing mode is selected and if the mission purpose is to spend a short flight time, the higher dynamic pressure climbing mode is selected. Larger wing load takes a longer time to reach the cruise altitude, and the flight distance is also longer. However, when the wing load exceeds a certain value, the supersonic cruise angle of attack will exceed the optimal angle of attack, and the maximum lift drag ratio of the cruise point can’t be fully utilized. The benefit brought by the fuel load of large takeoff weight is greater than the increase of fuel consumption brought by the reduction of thrust weight ratio, but the acceleration is poor in the subsonic accelerating climb, so the mobility in the subsonic climb is also an important constraint restricting the upper limit of the takeoff weight of the aircraft.
The porous-media-based electrospray thruster is a cutting-edge micropropulsion technology that can revolutionize the capabilities of microsatellites. This paper reports the design, fabrication, and characterization of a novel porous-media borosilicate glass electrospray thruster. The porous glass used here is integrally formed by the phase separation method, which make it display outstanding pore uniformity and processability. The picosecond ultraviolet laser processing technique is applied to machine 361 emitters out of glass. Performance characteristic experiments are conducted with the thruster passively fed with ionic EMI-BF4 liquid. The results reveal that the per-emitter can emit up to 200.46 nA of ion current at 2 kV. The novel porous glass and the corresponding machine method present an opportunity to attain more-controllable emitter shapes, which has a positive impact on thruster lifetime and performance improvement.
Solid fuel ramjets (SFRJs) have the advantages of light weight, simple structure, high reliability, high economy efficiency etc. During the transient situation, their actual time fuel consumption can be different from the simple linear control rules due to the limit of mechanical structures. The volume effect can also be treated as an influence factor of fuel. As a result, the dynamic characteristics of fuel will influence the transient performance of SFRJs. To better understand its impact, in-house models for SFRJs’ transient performance and fuel’s dynamic characteristics are built and simulated. During accelerating and decelerating processes, the actual time fuel consumption has characteristics of time-lag. There will exist thrust lost or superfluous thrust. Compared with acceleration processes, the dynamic characteristics of fuel would be more influential in deceleration processes.
Additive manufacturing methods have been widely used in applications for material preference in our daily lives, especially by enabling the production of complex geometry materials with precise tolerances. The purpose of being preferred in industrial applications is to produce alternative materials thanks to the Selective Laser Sintering (SLS) production system, which offers additive manufacturing. For this reason, in order to adapt the SLS system to the test samples, samples of 25x25x3mm 3 were produced from recycled PA 3200 GF powders to form a layer thickness of 100 μm.As a result of the impact of solid particles (especially aerospace systems, energy conversion plants, jet engines, helicopter rotor blades, etc.) with different properties on the material surface at certain velocity and angles, undesirable deformations occur on the material surface. In addition, this type of wear has a critical importance in the world economy. With this convergence, erosion wear tests were carried out in accordance with the international standard ASTM G76-95, prioritizing that material for the aerospace industry can be exposed to this type of wear thanks to the use of samples produced by additive manufacturing and containing recycling powders.In order to carry out solid particle erosion wear tests, especially for sand and dust effect, for the use of samples produced by SLS method and with a change in printing direction in different environmental conditions, taking into account the particle impact angle of 30°, 60° and 90°, under the influence of abrasive particles with Al2O3, SiO2 and C20 properties and experiments were carried out by modeling the operating conditions of 34 m/s impact velocity. Regardless of the printing direction effect, it was concluded that the highest erosion rate of the test materials in all groups occurred at the impact angle of 30°. Erodent properties also showed a dominant effect on the erosion wear mechanism. Moreover, the tangential and vertical efficiency of the abrasive particle impact have a significant effect on erosion wear.
This paper introduces an axial flow fan used in a train air-conditioning condensing system, which is the main sound source of the system. Firstly, in order to analyze the main causes of aerodynamic sound, the wind tunnel model of the axial flow fan for Computational fluid dynamics (CFD) analysis was established. The accuracy of the wind tunnel model was verified by axial fan P-Q performance curve and static pressure efficiency curve obtained from the test. Then the causes of aerodynamic sound of the axial flow fan was investigated by CFD analysis using the Large Eddy Simulation (LES) turbulence model and the Ffowcs Williams-Hawkings model (FW-H). Finally, three different optimization schemes of axial flow fan were proposed and compared with the prototype fan. The result shows that the pressure gradient at blade tip can be reduced by modifying blade airfoil and increasing chord length, and the aerodynamic noise of axial flow fan can be improved, which proves that the noise reduction scheme is effective.
