Analysis of Experimental and Numerical Studies of the Rudimentary Landing Gear

We present CFD results contributed by six groups at the workshop Benchmark problems for Airframe Noise Computations (BANC-1), held in Stockholm in June 2010, and experimental results obtained by the group led by Dr. Venkatakrishnan at the National Aerospace Laboratories (NAL) in Bangalore. The RLG appears successful as an opendomain test case, and likely to be the subject of sustained experimental and especially numerical efforts, and further workshops. The methods are Large-Eddy Simulation (LES) or a hybrid of LES with Reynolds-Averaged Navier-Stokes (RANS). The focus here is on wall quantities, especially as they are linked to noise generation, while actual noise predictions are left for later accounts. Surface distributions are displayed from CFD and experiment, and tables are presented of numbers thought to be meaningful, with the intent of later tracking progress and convergence between methods. The level of agreement for mean and fluctuating quantities is quantified as clearly as possible, hoping to describe today’s standards precisely. As expected, the agreement is tighter for “aerodynamic” quantities including near-field turbulence than for “noise” quantities, and we are far from having sufficient knowledge to anticipate the accuracy of far-field noise predictions. The general impression is of a good-willed and productive community effort. CFD, without a doubt, will some day reach industrial accuracy for noise just like it has for aerodynamics in the simpler regimes, but that the time frame for this is not known today, especially considering the much wider range of scales in real-life geometries.