Numerical Aerodynamics

More Precision for Aircraft Engine Jets

ONERA'scientists have developed a synthetic turbulence generator to simulate the development of aircraft engine jets with greater accuracy. The results are presented in a video.

Recent joint numerical and experimental studies carried out at Onera on aircraft engines highlighted the strong effect of the turbulence from the engine on jet development.

Since the models referred to as classical (RANS1) were unable to reproduce this effect, it was necessary to develop a synthetic turbulence generator dedicated to advanced ZDES2 / LES3 simulations. This development carried out with the elsA software now allows jet development to be simulated with great accuracy.

Work on jet turbulence modeling is of paramount importance because aircraft noise is mainly caused by turbulent jets, at the rear of the engines.

Representation of turbulent structures in jets in a by-pass configuration

1RANS - Equations "Reynolds-averaged Navier–Stokes"
These are the equations that describe turbulent flows, at the cost of simplifying assumptions. In particular, they are time-averaged and are suitable for relatively stationary flows.

2ZDES - Zonal Detached Eddy Simulation
 Method that allows a RANS-type model and a LES type model, located in the separated areas, to coexist in a single simulation. This means that the more powerful (and more expensive) model is only used when it is really necessary, allowing for acceptable simulation times. ZDES has been developed at Onera.

3LES - Large Eddy Simulation
[for large scale simulation] Technique for solving turbulent flow equations, where the large scales of motion are solved explicitly, while small scales (smaller in size than the calculation mesh) are modeled by an "eddy viscosity" term.

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