NUMERICAL MODELLING OF BIRD STRIKE ON A ROTATING ENGINE BLADES BASED ON VARIATIONS OF POROSITY DENSITY

A numerical investigation is conducted on a rotating engine blade subjected to a bird strike impact. The bird strike is numerically modelled as a cylindrical gelatine with hemispherical ends to simulate impact on a rotating engine blade. Numerical modelling of a rotating engine blade has shown that bird strikes can severely damage an engine blade, especially as the engine blade rotates, as the rotation causes initial stresses on the root of the engine blade. This paper presents a numerical modelling of the engine blades subjected to bird strike with porosity implemented on the engine blades to investigate further damage assessment due to this porosity effect. As porosity influences the decibel levels on a propeller blade or engine blade, the damage due to bird strikes can investigate the compromise this effect has on the structural integrity of the engine blades. This paper utilizes a bird strike simulation through an LS-Dyna Pre-post software. The numerical constitutive relations are keyed into the keyword manager where the bird’s SPH density, a 10 ms simulation time, and bird velocity of 100 m/s are all set. The blade rotates counter-clockwise at 200 rad/s with a tetrahedron mesh. The porous regions or voids along the blade are featured as 5 mm diameter voids, each spaced 5 mm apart. The bird is modelled as an Elastic-Plastic-Hydrodynamic material model to analyze the bird’s fluid behavior through a polynomial equation of state. To simulate the fluid structure interaction, the blade is modelled with Johnson-Cook Material model parameters of aluminium where the damage of the impact can be observed. The observations presented are compared to previous study of a bird strike impact on non-porous engine blades. ABSTRAK: Penyelidikan berangka telah dijalankan ke atas bilah enjin berputar tertakluk kepada impak pelanggaran burung. Pelanggaran burung tersebut telah dimodelkan secara berangka sebagai silinder gelatin dengan hujungnya berbentuk hemisfera demi mensimulasikan impaknya ke atas bilah enjin yang berputar. Pemodelan berangka bilah-bilah enjin yang berputar tersebut menunjukkan bahawa pelanggaran burung mampu menyebabkan kerosakan teruk terhadap bilah enjin terutamanya apabila bilah enjin sedang berputar oleh sebab putaran menghasilkan tekanan asal di pangkal bilah enjin. Kajian ini mengetengahkan pemodelan berangka ke atas bilah-bilah enjin tertakluk kepada pelanggaran burung terhadap bilah-bilah enjin yg mempunyai keliangan demi menyelidik dan menilai kerosakan kesan daripada keliangan tersebut. Keliangan juga mempengaruhi tahap-tahap desibel ke atas bilah kipas ataupun bilah enjin, kerosakan hasil serangan burung boleh menterjemah tahap ketahanan struktur integriti bagi bilah-bilah enjin tersebut. Penyelidikan ini mengguna pakai perisian “LS-Dyna Pre-post” untuk simulasi pelanggaran burung. Hubungan konstitutif berangka telah dimasukkan sebagai kata kunci di mana ketumpatan SPH burung, masa simulasi 10ms, dan halaju burung ditetapkan kepada 100 m/s. Bilah tersebut berputar pada 200 rad/s arah lawan jam dengan jejaring tetrahedron. Kawasan berliang atau kosong di sepanjang bilah ditetapkan diameternya kepada 5 mm, dan dijarakkan 5 mm di antara satu sama lain. Burung pula dimodelkan sebagai material “Elastic-Plastic-Hydrodynamic” untuk mengkaji sifat bendalir burung melalui persamaan polinomial. Demi mensimulasi interaksi struktur bendalir, bilah tersebut dimodelkan sebagai parameter aluminium material “Johnson Cook” di mana kerosakan daripada impak tersebut dapat diteliti. Penelitian-penelitian tersebut dibandingkan dengan kajian terdahulu ke atas serangan burung terhadap bilah-bilah enjin tidak berliang.

Effect of Impact and Bearing Parameters on Bird Strike with Aero-Engine Fan Blades

Bird strikes are one major accident for aircraft engines and can inflict heavy casualties and economic losses. In this study, a smoothed particle hydrodynamics (SPH) mallard model has been used to simulate bird impact to rotary aero-engine fan blades. The simulations were performed using the finite element method (FEM) at LS-DYNA. The reliability of the material model and numerical method was verified by comparing the numerical results with Wilberk’s experimental results. The effects of impact and bearing parameters, including bird impact location, bird impact orientation, initial bird velocity, fan rotational speeds, stiffness of the bearing, and the damping of the bearing on the bird impact to aero-engine fan blade are studied and discussed. The results show that both the impact location and bird orientation have significant effects on the bird strike results. Bird impact to blade roots is the most dangerous scenario causing the impact force to reach 390 kN. The most dangerous orientation is the case where the bird’s head is tilted 45° horizontally, which leads to huge fan kinetic energy loss as high as 64.73 kJ. The bird’s initial velocity affects blade deformations. The von Mises stress during the bird strike process can reach 1238 MPa for an initial bird velocity of 225 m/s. The fan’s rotational speed and the bearing stiffness affect the rotor stability significantly. The value of bearing damping has little effect on the bird strike process. This paper gives an idea of how to evaluate the strength of fan blades in the design period.

Severity assessment of aircraft engine fan blades under airborne collision of unmanned aerial vehicles comparable to bird strike certification standards

Airborne drone collision on commercial manned aircraft has received extensive awareness due to the increasing drone operations in the restricted airspace. In addition, the bird strike certification for aircraft engines is likely to be inadequate for a drone collision with identical kinetic energy due to the difference in damage levels. Thus, it is important to understand and compare the risk between drones and bird strikes. This study aims to understand the damage severity from bird and drone strikes on the manned commercial aircraft engine. The finite element method (FEM) simulation is adopted to obtain the damage of engine fan blades under the drone collision and bird strikes at different collision positions. The Lagrangian and smoothed-particle hydrodynamics approaches are employed for the drone and bird simulations, respectively. In addition, three different drone and bird weight categories were considered in this study, namely, small, medium, and large, to investigate the effect of kinetic energy on the damage of fan blades. Results from the FEM simulation demonstrated that the damage of the engine fan blades due to drone collisions were more severe when comparing bird strikes of the same weight category. The damage severity level was proposed based on the damage of engine fan blades. In the event of a drone ingestion, the damage severity level assists in the identification of potential damage to engine fan blades and its performance.

Investigate the Crashworthiness of high-velocity bird impact on three different designed model wings by using Coupled Eulerian-Lagrangian approach

Bird strike is a significant threat to the parts of the flying aircrafts. The wing is a central part, which provides stability to the aircraft. Mostly at wing, bird attack the leading edge. Worldwide aviation regulation FRA, EASA, required 4Ib bird strike on the wing of aircraft, and after this bird strike, aircraft is able to be safely landed. This study aims to investigate the resistance of the wing against the bird strike and damage analysis of the high-velocity bird collision on the model wing, inner structure, spar, and ribs. By using the Coupled Eulerian-Lagrangian (CEL) approach in ABAQUS/Explicit. Our contribution 1) bird strike on a wing with assembled inner structure by aluminium and outer skin composed of unidirectional fiber-reinforced composite material. 2) bird strike on-wing which is similar with the first test in which the difference is of spar designed layers of horizontal plates like a comb. 3) bird strike on-wing which is similar with second model wing difference in this wing put an aluminium leading edge on the skin leading-edge, final to analyze the damage of bird impact on the wing, the velocity of bird strike is 200m/s and analyze the behavior of the bird at this velocity. Resistance behavior of composite skin After penetration in the wing, analyze the impact on the spar and stress on the inner structure. Analysis of the kinetic and internal energy graph and Comparison all of these results and check the performance, which gives an excellent result at this velocity. based on these results suggest which inner part is sensitive.

Dynamic Responses of the Aero-Engine Rotor System to Bird Strike on Fan Blades at Different Rotational Speeds

To study the effect of a bird striking engine fan on the rotor system, a low-pressure rotor system dynamic model based on a real aero-engine structure was established. Dynamic equations were derived considering the case of the bird strike force which transferred to the rotor system. The bird strike force was obtained from the bird strike process simulation in LS-DYNA, where a smoothed particle hydrodynamics (SPH) mallard model was constructed using a computed tomography (CT) scanner, and finite element method (FEM) was used to simulate the bird strike on an actual fan model. The dynamic equations were solved using the Newmark-β method. The effect of rotational speeds on the rotor system dynamics after bird strike was investigated and discussed. Results show that the maximum bird impact force can reach 104 kN at 3772 r/min. Impact time is only 0.06 s, but the bird strike on fan blades lead to a transient shock on the rotor system. Under the action of transient shocks, the rotor system displacement in the horizontal and vertical directions increase sharply, and the closer the mass point is to the fan, the more it is affected; the vibration amplitude at the fan will increase 15 times within 0.1 s of the bird strike and will gradually decrease with the effect of damping. The dynamics of the rotor system changes from a stable single periodic motion to a complex irregular quasi-periodic motion after a bird strike, and the strike force excites the first-order vibrational mode of the rotor system. This phenomenon occurs at all speeds when bird strikes occur. Bird strikes will cause resonance in the rotor system, which may cause damage to the engine. It was also seen that the bird strike force, and hence the effects on the rotor system, increases as the engine rotational speed increases; the peak force is larger and the number of peaks has increased. The impact force at 3772 r/min is 99.5 kN higher than at 836 r/min, and three additional peaks emerged. This effect is more reflected in the amplitude, and the overall vibration characteristics do not change. Combining the bird strike with the rotor dynamics calculation, the dynamic response of the aero-engine rotor system to bird strike is studied at different flight stages, which is of guiding significance for power evaluation of aero engines after bird strike.

Isolated medial rectus muscle laceration after bird strike

Introduction: A 66 year-old male suffered globe trauma due to A bird, a German Desert Hawk, strike. At the first examination in the emergency ünit a few hours after the injury, the patient reported persistent horizontal diplopia. Case report: He had right conjunctival laceration, mild proptosis, subconjunctival hematoma, exotropia with no adduction. Magnetic Resonance Imaging (MRI) revealed that it was suggestive of laceration of the right medial rectus muscle, at about the junction of it’s anterior and middle thirds. During surgery; initially, the lacerated proximal end of the distal segment was isolated. The proximal segment of the medial rectus muscle was then carefully dissected. The two lacerated ends were then joined with 6-0 polyglactin sutures. Conclusion: The day after surgery, there was no deviation and diplopia in all diagnostic gaze positions.