Numerical Simulations of High Temperature Jets from the ...mdx2.plm.automation.siemens.com/sites/default/files/Presentation/... · Power Unit Impinging Against a Construction of the

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Numerical Simulations of High Temperature Jets from the Main Propulsion System and Auxiliary Power Unit Impinging Against a Construction of

the Passenger Plane

Kudryavtsev A. Yu., Zhelezov S.A., (Sarov Engineering Center)

Polovin M.M., Litvinov M.S. (Sukhoi Civil Aircraft)

STAR Global Conference 2012, March 19-21, Amsterdam

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MPU APU Accidental High Temperature Jets


All newly designed passenger planes must meet safety and reliability requirements in possible emergency situations, one of which is a burn-through of a combustion chamber body of the main propulsion system (MPS) and auxiliary power unit (APU) both on the ground and in flight.

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Problem Statement

In accordance with the international safety standards, an emergency case is investigated using STAR-CCM+ and Abaqus when due to local disruption of the combustion chamber a flame jet is erupted. As a result of the flame jet impingement some parts of the airplane construction can substantially be heated, deformed and, possibly, disrupted. The following variants of jet are considered: 1. MPS: Temperature and pressure in the combustion chamber: Тflame=1527ºС, Р=22,3 bar; 2. APU: Temperature and pressure in the combustion chamber: Тflame =1015ºС, Р=10,6 bar. Duration of the flame jet eruption t ≤ 5 sec in all cases. This presentation gives results of numerical investigations of deformation of airplane parts entering the zone of possible gas-dynamic and thermal effects from the flame jet.


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Methodology of simulation Solution of the problem is divided into three stages : 1. Gas-dynamic problem 2. Heat-transfer problem 3. Stress analysis problem

The result of solving the gas-dynamic problem is the pressure, temperature and the heat transfer coefficient on the surfaces. Temperature and HTC are then used as boundary conditions for solving the heat transfer problem. The result of solving the heat problem is a three-dimensional temperature field for all the details. The resulting solution of the temperature field is interpolated on the finite element model, where it is based on the calculated mechanical properties of materials.

Tambient, Htran

Tvolume

Heat transfer problem

Stress analysis problem

Gas-dynamic problem

Pressure


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Methodology of simulation

Gas-dynamic problems are solved in a steady-state formulation, stress - in the static. The thermal calculations were carried out both in steady-state and in transient variant. The calculation results show that during the jet flame impact T = 5 sec., the temperature of the studied elements of the airframe and the pylon reaches maximum, and does not to grow up further. A solution of the stationary and transient problem for final moment of time are identical. With regard to the this type of problem, the steady-state solution is worse and provide heavier loads to parts of the airplane construction than the solution of the transient problem for any finite time.


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Case 1: APU high temperature jet


Computer model: • based on the polyhedral cells • 5 mln cells for fluid • 3 mln cell for solid

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Finite element model, contains 366 000 elements



8 STAR Global Conference 2012, March 19-21, Amsterdam


Pressure Temperature

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Temperature reaches maximum value Tmax = 850 C at the time t = 0.1 sec., which is much less than melting temperature for this material Tmelting = 1640 C

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Contours of resultant displacement (m)



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Conclusions: • through hole does not appear due to of melting;

• rupture of the part in the zone of the maximum pressure does not occur.



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Case 2: MPU high temperature jet


Computer model: • based on the trimmed cells • 3 mln cells for fluid • 0.5 mln cell for solid

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Case 2.1: MPU high temperature jet, penetration of the fire protection shield



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In this case temperature of jet is T = 1527 C and melting temperature T = 1496 C. Temperature of the shield reaches critical value to the t = 2.5 sec. Therefore it is expected that though hole will appear just due to the melting. But size of hole can increase as result of jet pressure force.



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Evolution of the cavern in time



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Finite element model:

T = 2 sec.


T = 4 sec.

T = 3.5 sec.


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Т=2 sec. Т=3.5 sec.

Contours of resultant displacement



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Т=4 sec. Т=5 sec.

Case 2.1: MPU, left side of the pylon, penetration of the fire protection shield


Contours of resultant displacement

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Conclusions: • at time ~ 3.5 sec. fire protection shield breaks though, hole continues enlarging mainly due to melting of the material, influence of jet pressure to size of hole is minor; • to the 5th second the hole takes the final shape and size, the further the increasing of hole does not occur.



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Case 2.2: MPU high temperature jet, jet flame propagation


Propagation of the jet flame into the compartment of pylon

Computer model: • based on the trimmer cells • 2.5 mln cells for fluid

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Case 2.2: MPU high temperature jet, jet flame propagation

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Conclusion: • Using of STAR-CCM+ allowed in short time investigate different scenarios of possible accident of the board of the new aircraft and prove safety of the its construction.


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Thank you for your attention


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Numerical Simulations of High Temperature Jets from the ...mdx2.plm.automation.siemens.com/sites/default/files/Presentation/... · Power Unit Impinging Against a Construction of the