飞机迎风面蒙皮涂层高动态雨蚀损伤评价和机理OA

When an aircraft flies at high speed in the rain,the skin coating on the windward side of the fuselage is damaged by the impact of raindrops.In order to ensure the safety of flight,the rain erosion damage mechanism of the skin coating is studied in depth.To simulate the raindrop impact,a single-jet test platform constructed by a first-class light-air gun and a multi-jet test platform modified by a water-cutting device were utilized.Rain erosion tests were conducted on the materials under different experimental conditions,where the substrate is made of carbon fiber T300 woven fabric,and its surface is coated with three types of polyurethane coating materials of equal thickness.Single-jet flow tests were performed on three coating materials at an impact velocity of 617 m/s and impact angles of 0°,15°,and 30° as well as on three coating materials at impact velocities of 430,490,and 555 m/s and an impact angle of 15°.Multi-jet flow tests were performed on three coating materials at impact velocities of 350,370,and 420 m/s with 1 000 impacts.The results showed that,with the change of impact angle and velocity,the damage trend of the three coating materials was consistent and the typical damage morphology was the same.For example,when the water hammer pressure was lower than the yield strength limit of the coating material,the damage area consisted of a ring-shaped region encircling the central uninjured area,and when the water hammer pressure was higher than the yield strength limit of the material,the combination of the water hammer pressure with the lateral jet would cause a damage area 1-2 times the diameter of the liquid droplet.Under the impact of a single jet,the damage profile of the coating material was not symmetrical,and the damage profile in the transverse direction was larger than that in the longitudinal direction.This occurred because the jet was affected by gravity during flight,which produced a downward drop,resulting in hindered lateral jet propagation in the vertical direction.Under the impact of multiple jets,the damage critical velocities of materials 1 and 2 were in the range of 320-350 m/s and the damage critical velocity of material 3 was slightly lower than 320 m/s.Different materials produced distinct erosion pit shapes under the impact of multiple jets.These shapes affected further erosion differently:flat-bottomed pits promoted erosion,while sharp-bottomed pits mitigated it.There was a similarity between the test results for single and multiple jets.Comparing the typical damage morphology of the coating materials under single-jet and multi-jet tests,it was found that the rain-etching damage mechanism of the materials was closely related to their own mechanical properties,but not to the impact mode.Based on the damage results of the three coating materials under different test parameters of single and multiple jets,material 1 performs best under different rain field impacts simulated by the test and can adapt to the aircraft under different flight conditions.