Abstract
This paper presents a numerical investigation of bird attitude angles affecting the soft-impact damage of a full fan assembly. Firstly, considering the geometry of a mallard, a real bird model is established by the Smoothed Particle Hydrodynamics (SPH) method and calibrated with available test data. Then, complying with airworthiness requirements, simulations of a full-bladed fan assembly subjected to a real bird were conducted to determine the critical ingestion parameters (CIP). Furthermore, a real bird with different attitude angles aimed at a full fan assembly was simulated. Results show that attitude angles of the bird produce a significant impact on the effect of the bird strike on rotating blades and would increase the possibility of blade failures, especially for the yaw angle of -45° and the pitch angle of −60°. It is invaluable for commercial airlines and engine manufactures to provide safe flight and landing by adopting the real bird model with critical yaw and pitch angles in the design for resistance to bird ingestion.
Highlights
Bird strikes have been presenting the main threat to aircrafts since the beginning of aviation history
D1, D2, D3, D4, D5 -0.09, 0.25, -0.5, 0.14, 3.87 reason that the initial bird loading area is almost like a point loading [29]. e focus of blade damage analysis needs to be on accurately capturing the steady stagnation pressure phase of impact [27]. us, the stagnation pressure is represented as a criterion to calibrate bird models
A segment sensor was assigned at the center of the plate to extract the impact pressure. e stagnation pressures were estimated by averaging the pressure between T0/3 and 2T0/3 [26], where T0 denotes the duration of the bird strike event
Summary
Bird strikes have been presenting the main threat to aircrafts since the beginning of aviation history. According to a large number of reported bird-strike incidents, substantial damage to aircraft structures occurs even though the involved energies of the bird did not achieve the aircraft certification standard. It indicates that only taking the mass and impact speed of the bird into account is far from enough. Wilbeck [3, 4] conducted a comprehensive set of experimental studies on bird impacts on various structures regarding different bird sizes, initial velocities, bird substitutes, and oblique impacts. It can be concluded that the substitute model with bird shapes, namely, ellipsoid and hemispherical-ended cylinder (aspect ratio of 2), is recommended, associated with material properties of homogenized fluidic materials. e equation of state is used to describe the compressibility characteristics of bird material
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