VALIANT 7FP EC Project Meeting

The «Validation and optimization of aerodynamic noise simulating tools» meeting of all partners of the VAALIANT 7FP EC project was held in the Moscow Complex of TsAGI, September 2–3, 2010.The VALIANT project was kicked off on September 1,2009. It was mainly targeted at the adjustment of mathematical simulation methods used to estimate airframe components airflow aerodynamic noise.

The problem of noise that is generated when the under-carriage and lift devices (slats, flaps and spoilers) airflow emerges when the aircraft is performing the landing approach, when the engines are idle and the aircraft power-plant noise is no longer dominant, as compared to other noise sources. Creating advanced civil aircraft with enhanced acoustic properties that meet the ICAO vicinity noise norms is undergoing increasingly more severe demands, especially the significant reduction of airframe components flow noise as compared to existing aircraft.

The design of optimal methods to alleviate the noise of aerodynamic origin needs an integrated approach that provides the ability of the developed noise reduction techniques not to deteriorate the performance characteristics of the rest of the aircraft systems. That is why the creation of mathematical models of noise generation processes is one of the foremost tasks of modern aeroacoustics. Unfortunately, the current status of numerical methods of modeling makes it impossible for them to be used when searching for novel ways to reduce the noises of different aircraft, and in particular as far as it concerns the airframe structures noise flow.

The VALIANT project is aimed exactly at thendevelopment of numerical methods of modeling that could be used in the research of new ways to reduce the airframe structure noise. To obtain this target the model flows were selected. On one hand they have simplified geometrical configurations, but on the other hand they correspond completely to noise generation physics when flowing over the airframe components. At the first project stage these flows will be investigated experimentally (measuring the aerodynamic and aeroacoustic properties), and at the second stage the numeric simulation of all measured parameters of these model flows is to be carried out.

TsAGI contributes to the experimental part of the project. At the preliminary draft design stage specialists of the acoustic department proposed to use for numerical simulation and experimental modeling one of the most important noise generation phenomena when flowing over flaps and slats, i. e., the phenomenon of quasi-monopole acoustic radiation of slots with turbulent flow around them. This solution was supported by the project partners and TsAGI was authorized to be a leader of a Workpackage. The numeric simulation for the abovementioned phenomenon will be performed by MMI RAS, DLR, NLR and TUB.

In the course of the preceding meeting that was held by TsAGI, the VALIANT project partners presented the results obtained during the first working year.

In conformity to the work schedule the Experimental Production Shop of TsAGI manufactured a plate with a rectangular perforation. The plate and the nozzle were integrated. The trial acoustic measurements were executed in the AK-2 acoustic chamber in order to demonstrate the operability of the model in terms of acoustic radiation perceptibility and the ability to simulate numerically the emerging phenomena that were directly demonstrated to meeting participants.