The bird-strike problem for aircraft is introduced

1. Rajasthan Technical University, Kota
Seminar Presentation
Effect of Bird Strike on Jet Engine
Under the guidance of –
Mr Anshul Bansal
Asst. Professor
Rajasthan Technical University, Kota
Submitted to –
Department of Mechanical Engineering
Rajasthan Technical University, Kota

2. Effect of Bird Strike
on Jet Engine
Seminar Presentation
Submitted by-
Mahendra Gehlot
15/551
A1 Aeronautical Engineering

3. What is bird strike?
• Any contact between a moving vehicle (aircraft) and an airborne
avian creature (usually a bird or bat) or a group of such avian
creatures

4. Location of bird strike on aircraft
Figure – Location of bird strike [1]

5. Effect of bird strike on Aircraft
Figure – Jet engine being affected after bird strike [1]

6. Factors to be consider to predict effect of bird strike
• Bird size
• Bird weight
• Bird orientation
• Aircraft speed
• Angular velocity of engine
• Engine type
• Location of impact

7. How bird ingestion affect performance?
• Bird strikes usually occur at the inlet of the engines
• Small birds do not usually pose a big problem to the engine
• Small birds do not usually impose damage to the internal rotors of the
engine
• In more serious impacts, the bird can severely bend the blades of the
frontal rotor which after being broken are thrown out either sideways,
forward, or backward
• The most dangerous case occurs when the broken blades are thrown
backward which can cause a chain breakage of the blades of the next
rotors and the compressor[2]
• Small engine is more susceptible to be repeatedly hit and damaged by
each ingested bird because of their higher angular velocity compared to
larger engines

8. How bird ingestion affect performance?
• The blade of large engines usually sustain “local” damages such as
dents, tears, and curl-backs, whereas small engine blades usually
experience extensive airfoil untwist, extensive airfoil flexure, or
blade root fracture[4]
• The blades of small engines can be damaged by small, medium,
and large birds, while the large engine blades are not usually
affected by small birds because the large blades easily chop them

9. Bird ingestion in engine

10. Bird strike – A case study
• Anghileri et al. [3] investigated a 4 lb bird strike into a turbofan
engine using experimental tests and numerical modelling
• The engine intake had the capability of withstanding a bird with
initial velocity of 265 knots, but was destroyed in a subsequent
impact with 360 knots initial velocity
• The nose-lip was not able to bounce back the bird without being
damaged
• The hitting bird created a pocket-shaped cavity in the nose-lip and
after being deflected it struck the aft-bulkhead

11. Continue…..
• For the numerical modelling, an SPH bird model was created in
LSTC/LS-DYNA
• The final shape of the turbofan structure and the structure failure
mechanisms were very similar to the observation of the
experimental tests

12. Continue…
Figure - Damage in the nose-lip of a
turbofan engine (Anghileri et al.,
2005).
Figure - Results obtained from the
SPH model of a bird strike
(Anghileri et al., 2005).

13. Various researches…
• In a numerical simulation of a bird strike into turbojet engine fan blades
(Shmotin et al [5]), it was shown that the coefficient of friction does not
have a direct effect on the generated strains in the blades
• In numerical simulations carried out by Meguid, Mao, & Ng (2008), bird
models with different geometries including hemispherical-ended
cylinder, straight-ended cylinder, and ellipsoid, and also three different
length-to-diameter aspect ratios were impacted to a single static fan
blade[6]
• Orientation of the bird with respect to the engine axis can have significant
effects on the damage imposed to the engine structure [7]

14. Continue…
Figure - Comparison of normalized pressure profiles of birds with three configurations
when striking a single fan blade [6].

15. Things to be consider for safe flight operation
• The aircraft safety standards allow failure of the intake itself, but
malfunction of the equipment behind the intake is not tolerated
• Intake should deflect the bird or absorbs the most part of its energy
before the bird reaches the internal parts of the engine[3]
• Even the minor damage into the blades creates an uneven distribution of
mass around the rotation axis. The mismatch of the mass centre of the
blade system and the rotor axis causes a torsional moment which gives
the rotor a wobbling movement characteristic
• According to current airworthiness standards, the engine must be able to
continue its safe flight by not losing more than 25% of its thrust for 20
mins after being impacted by four medium-sized birds, each weighing 1.1
kg and/or one large bird weighing 3.6 kg

16. Bird Strike Prevention Method
• Prevention : on-board equipment
• Prevention : Airport
• Bird-proofing regulation
• Experimental ingestion tests
• Numerical Approaches

17. Prevention – on board equipment
• Onboard aircraft systems such as pulsed landing lights, strobe
lights, colour schemes, infrasound, and microwave generators, can
warn wildlife of approaching aircraft [8]
• If the birds are alerted of the approaching aircraft at a sufficiently
great distance, they can use their inherent flight manoeuvres to
escape the aircraft path in a similar way to which they respond to
aerial predators [9]

18. Prevention – Airport
• Aircraft flight path and schedule modifications
• Habitat modification and exclusion
• Repellent and harassment techniques
• Wildlife removal

19. Bird-Proofing regulation
• Bird-ingestion regulation can be seen in 14 CFR 33.76.
• Typical Experimental Setup consist
• Gun systems
• Support systems
• Measurement systems
• Bird impactors

20. RR Engine – Bird ingestion testing
This video may be subject to copyright.

21. Bird-Proofing regulation
• Numerical Approaches
• In high velocity impacts, the pressure on bird tissues severely exceeds the
tissues tolerable values, making the bird’s material actually behave like a fluid.
To discretize the bird model, there are generally three well-established
approaches:
• Lagrangian
• Arbitrary Lagrangian Eulerian (ALE)
• Smoothed Particle Hydrodynamics (SPH)
• LS-DYNA

22. References
1. https://www.boeing.com/commercial/aeromagazine/articles/2011_q3/4/
2. Blokpoel, H. (1976). Bird hazards to aircraft. Clarke
(https://www.refhub.elsevier.com/B978-0-08-100093-9.00007-8/rf0050)
3. Anghileri, M., Castelletti, L. M., & Mazza, V. (2005). Birdstrike: approaches to the
analysis of impacts with penetration. In Impact loading of lightweight structures
(pp. 63–74).
4. Teichman, H. C., & Tadros, R. N. (1991). Analytical and experimental simulation of
fan blade behaviour and damage under bird impact. Journal of Engineering for
Gas Turbines and Power, 113(4), 582–594.
5. Shmotin, Y. N., Chupin, P. V., Gabov, D. V., Ryabov, A. A., Romanov, V. I.,
Kukanov, S. S., & Saturn, N. (2009). Bird strike analysis of aircraft engine fan. In:
7th European LS-DYNA users conference, Salzburg, Austria, May 14A¯ 19, LSTC,
Livermore, CA.
6. Meguid, S. A., Mao, R. H., & Ng, T. Y. (2008). FE analysis of geometry effects of an
artificial bird striking an aeroengine fan blade. International Journal of Impact
Engineering, 35(6), 487–498.

23. References
7. Hedayati, R., & Ziaei-Rad, S. (2013). A new bird model and the effect of bird
geometry in impacts from various orientations. Aerospace Science and Technology,
28(1), 9–20.
8. MacKinnon, B., Sowden, R., & Dudley, S. (2001). Sharing the skies: An aviation
guide to the management of wildlife hazards. Ottawa, Ontario: Transport Canada.
9. Blackwell, B. F., DeVault, T. L., Seamans, T. W., Lima, S. L., Baumhardt, P., &
Ferna´ndez-Juricic, E. (2012). Exploiting avian vision with aircraft lighting to
reduce bird strikes. Journal of Applied Ecology, 49(4), 758–766.
10. Reza Hedayati, Mojtaba Sadighi . Bird Strike - An Experimental, Theoretical, and
Numerical Investigation.