What is it about?

Analyze the dynamic characteristics of hammer shock caused by engine surge, a serpentine inlet with a front fuselage is simulated under conditions of subsonic inflow and three flight angles, based on improved delayed detached eddy simulation method. An unsteady back pressure boundary condition in the Aerodynamic Interface Plane is used to simulate the overpressure during engine surge. There is a certain angle between the normal line of the hammer shock and the centerline, which is approximately equal to the corresponding flight angle. The inlet wall pressures are above 2.3 times of the free-stream static pressure, and even local transient pressures reach more than 3 times. Complex flow field structures are generated behind the shock which affected by centrifugal force and lateral pressure gradient.The velocities and intensities of the hammer shocks, the pressure distributions on the wall and the shapes of the flow field structures are greatly affected by the flight angle. In large yaw angle, the hammer shock velocity is the fastest, internal airflow and load are the most severe. In particular, it is necessary to consider the influence of the ultra-high dynamic loads in the opposite direction at the two bends in a short period of time.

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Why is it important?

In the design of the serpentine inlet structure, it is necessary to evaluate the ultra-high impact pressure loads of the hammer shocks generated by the engine surge and ultra-low pressure loads at the time of the backflow, and the application of the pressure loads in the opposite direction for a short time has a severe test on the safety of the inlet structure. Among them, attention must be paid to the hammer shock load on the inlet structure at large yaw angle.


The research in this article can clearly observe the occurrence of hammer shock in the serpentine inlet, which is of great engineering value.

PeiLi Wu
Northwestern Polytechnical University

Read the Original

This page is a summary of: Dynamic characteristics analysis of hammer shock in serpentine inlet, AIP Advances, January 2021, American Institute of Physics,
DOI: 10.1063/5.0018140.
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