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) 1
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. 2
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: Т flame =1527ºС, Р=22,3 bar; 2. APU: Temperature and pressure in the combustion chamber: Т flame =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. 3
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. Gas-dynamic problem Pressure T ambient, H tran Heat transfer problem T volume Stress analysis problem 4
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. 5
Case 1: APU high temperature jet Computer model: based on the polyhedral cells 5 mln cells for fluid 3 mln cell for solid 6
Case 1: APU high temperature jet Finite element model, contains 366 000 elements 7
Case 1: APU high temperature jet Pressure Temperature 8
Case 1: APU high temperature jet Temperature reaches maximum value T max = 850 C at the time t = 0.1 sec., which is much less than melting temperature for this material T melting = 1640 C 9
Case 1: APU high temperature jet Contours of resultant displacement (m) 10
Case 1: APU high temperature jet Conclusions: through hole does not appear due to of melting; rupture of the part in the zone of the maximum pressure does not occur. 11
Case 2: MPU high temperature jet Computer model: based on the trimmed cells 3 mln cells for fluid 0.5 mln cell for solid 12
Case 2.1: MPU high temperature jet, penetration of the fire protection shield Pressure Temperature 13
Case 2.1: MPU high temperature jet, penetration of the fire protection shield 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. 14
Case 2.1: MPU high temperature jet, penetration of the fire protection shield Evolution of the cavern in time 15
Case 2.1: MPU high temperature jet, penetration of the fire protection shield Finite element model: T = 2 sec. T = 3.5 sec. T = 4 sec. 16
Case 2.1: MPU high temperature jet, penetration of the fire protection shield Contours of resultant displacement Т=2 sec. Т=3.5 sec. 17
Case 2.1: MPU, left side of the pylon, penetration of the fire protection shield Contours of resultant displacement Т=4 sec. Т=5 sec. 18
Case 2.1: MPU high temperature jet, penetration of the fire protection shield 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. 19
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 20
Case 2.2: MPU high temperature jet, jet flame propagation Pressure Temperature 21
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. 22
Thank you for your attention 23