274
X. Zhang and Q. Zhang
not specified. The national military standard GJB 2464-95 stipulates that the shape
of bird body should adopt a cylinder with a length-to-diameter ratio of 2:1. Therefore, some domestic researchers used a cylindrical bird body for birdstrike research.
Yongkang and Yulong [1] used the cylindrical bird body to study the bird modelling
method under different impact speeds. Guida et al. [2] analysed the anti-birdstrike
performance of GLARE plates with different layers using a cylindrical bird body.
According to Heimbs’s review of birdstrike research [3], the bird shape of cylinders
with hemispheres at both ends was most used. Hu et al. [4] used this bird shape to study
the response of birdstrike of helicopter, which was consistent with the experiments.
In addition, ellipsoidal bird body is also widely used. Diamantakos et al. [5] used
ellipsoidal bird body in the airworthiness certification of composite leading edge to
establish a set of experimentally validated numerical simulation tools for birdstrike.
Georgiadis et al. [6] also used ellipsoid bird body in the airworthiness certification
of the Boeing 787 tail structure. On the other hand, the sphere-shaped bird body has
few applications. Zammit [7] used the sphere-shaped bird in the birdstrike study of
metal blade and composite blade.
Shuhua and Mingbo [8] found that the bird shape is one of the reasons of mismatch
between the simulation and test. In their birdstrike study on windshield, a cylindrical
bird with hemispheres at both ends was closest to the test. At the same time, there
were other research results showing that the cylinder is more in line with the real
bird [8, 9]. Different kinds of birds have different density, bone hardness, weight
distribution, as well as different impact speeds. Therefore, different studies drew
different conclusions. The actual birdstrike situation may be more complicated. There
are statistical differences in birds in different natural environments [10], and there are
obvious differences in the impact response for different bird parts [11]. Therefore,
it is difficult to get a unified conclusion even through experiments. It also makes it
less meaningful to find the shape of the bird closest to the experiments.
The purpose of the birdstrike test is to ensure the safety of the aircraft, that is,
the aircraft can safely return under the most severe birdstrike damage. Therefore,
the aim converts to determine the shape of bird body that causes the most serious
damage to the engine. In this paper, four shapes of bird body are considered and their
models are established. The response of the four birds impacting the engine blade are
investigated by numerical methods, and the impact risks are analyzed to determine
the bird shape that can cause the most severe damage at the same mass.
22.2 Birdstrike Model
22.2.1 Bird Modeling
There are four commonly used bird shapes: cylinder, ellipsoid, sphere, and cylinder
with hemispheres at both ends, as shown in Fig. 22.1. The lengths of cylinders,
ellipsoids, and cylinders with hemispherical ends are all twice their diameters.
X. Zhang and Q. Zhang
not specified. The national military standard GJB 2464-95 stipulates that the shape
of bird body should adopt a cylinder with a length-to-diameter ratio of 2:1. Therefore, some domestic researchers used a cylindrical bird body for birdstrike research.
Yongkang and Yulong [1] used the cylindrical bird body to study the bird modelling
method under different impact speeds. Guida et al. [2] analysed the anti-birdstrike
performance of GLARE plates with different layers using a cylindrical bird body.
According to Heimbs’s review of birdstrike research [3], the bird shape of cylinders
with hemispheres at both ends was most used. Hu et al. [4] used this bird shape to study
the response of birdstrike of helicopter, which was consistent with the experiments.
In addition, ellipsoidal bird body is also widely used. Diamantakos et al. [5] used
ellipsoidal bird body in the airworthiness certification of composite leading edge to
establish a set of experimentally validated numerical simulation tools for birdstrike.
Georgiadis et al. [6] also used ellipsoid bird body in the airworthiness certification
of the Boeing 787 tail structure. On the other hand, the sphere-shaped bird body has
few applications. Zammit [7] used the sphere-shaped bird in the birdstrike study of
metal blade and composite blade.
Shuhua and Mingbo [8] found that the bird shape is one of the reasons of mismatch
between the simulation and test. In their birdstrike study on windshield, a cylindrical
bird with hemispheres at both ends was closest to the test. At the same time, there
were other research results showing that the cylinder is more in line with the real
bird [8, 9]. Different kinds of birds have different density, bone hardness, weight
distribution, as well as different impact speeds. Therefore, different studies drew
different conclusions. The actual birdstrike situation may be more complicated. There
are statistical differences in birds in different natural environments [10], and there are
obvious differences in the impact response for different bird parts [11]. Therefore,
it is difficult to get a unified conclusion even through experiments. It also makes it
less meaningful to find the shape of the bird closest to the experiments.
The purpose of the birdstrike test is to ensure the safety of the aircraft, that is,
the aircraft can safely return under the most severe birdstrike damage. Therefore,
the aim converts to determine the shape of bird body that causes the most serious
damage to the engine. In this paper, four shapes of bird body are considered and their
models are established. The response of the four birds impacting the engine blade are
investigated by numerical methods, and the impact risks are analyzed to determine
the bird shape that can cause the most severe damage at the same mass.
22.2 Birdstrike Model
22.2.1 Bird Modeling
There are four commonly used bird shapes: cylinder, ellipsoid, sphere, and cylinder
with hemispheres at both ends, as shown in Fig. 22.1. The lengths of cylinders,
ellipsoids, and cylinders with hemispherical ends are all twice their diameters.