Wind turbine installations at near-shore and off-shore sites focuses attention on the operating conditions in very aggressive environments, characterized by the presence of sand, dust and saline moisture in the air stream. The environment causes rotor blade erosion of the leading edge, thinning of the trailing edge and roughness increase all over the rotor blade surface; these effects produce severe performance decay, as lift reduces and drag increases. Test analysis has been performed, with a water-table test-bench at “La Sapienza” University of Rome, on the performances of some new profiles, designed for wind turbine rotor blade applications. The results are compared with literature and previous experimental measures.

The ingestion of solid abrasive particles and/or foulants causes erosion of the compressor blades, resulting in a considerable reduction in the performance and working life of aviation/heavy duty GT and an increase in fuel consumption. The geometry variation at the Leading Edge (L.E. blunting) and Trailing Edge (T.E. thickness reduction), together with the general increase of airfoil surface roughness, depends on the characteristics of the incident particles, the geometry and the materials of the blade cascade, the dynamic parameters of the particles and on the type of impact. In order to rectify this degradation in performance, it is therefore necessary to re-profile the blades with machining that is highly critical for the performance of the engine, the life of the compressor blades and for maintenance costs. In order to determine an optimum and cost effective process of reprofiling, a series of tests reproducing the corresponding models of flow have been carried out on the Water Table Test Bench using Lamb’s hydraulic analogy relative to profiles of the VII and VIII stage HP of the compressor of the GT CF6-50 (G.E. Co.). The tests were carried out both on the isolated airfoil profile and on the blade cascade and both in the original conditions, at varied geometry (because of erosion and/or fouling) and after re-profiling. The trajectories of the particles have been visualised in several ways (like a false color photographic procedure), confirming results reported by various authors related to the model of impact and erosion. Particularly in the case of the dust aspiration during the arrival phase on the deck of an aircraft carrier. The test results have been discussed and compared with those available in scientific literature.

No abstract

Combat helicopters frequently operate in the part of Planetary Boundary Layer (PBL) characterised by the presence of dust and many other aggressive agents, particularly, in desertic areas and in marine sites, so the aerodynamic performance of their ailerons reduced spanwise, carrying out weapon systems, may be reduced within unacceptable values and consequent relevant risks for the stability of the copter. According to some experts, ailerons for weapon systems of helicopter are not involved in the global lift of the copter, but their operative function is only to carry the combat systems..Nevertheless, some crash occurred to US combat helicopters suggest a different point of view, and an aileron damage, perhaps due to a kind of dynamic stall phenomenon, seems have been caused the copter fall. These problems may be avoided using particularly airfoil for the section of aileron instead of classic ones as NACA four digit series (as 00120018). These profiles may be FFA-W1-XXX series, characterised by a double curvature of camber-line. In the present paper, after a deep analysis of operative conditions of modern combat helicopters, the aerodynamic performance of aileron section as NACA 0018 and FFA-W1-182 have been analysed and compared, and the results of tests carried out on a water table test bench are exposed and discusses.

Recently, offshore wind plants, as Horn’s Riv one, have reached a remarkable interest and development. In these sites, HAWT’s blades experiment corrosion, erosion and fouling and, at higher latitudes, icing conditions too, as in mountainous areas and in harsch climate sites. The operative conditions may influence the machine damages and they may occur as consequence of erosion, corrosion, fouling, icing, exfoliation caused by the above mentioned environmental conditions. The paper reports about data collection about failures occurred to HAWTS operating in offshore, mountainous and harsch climate sites in last ten years. Particularly, the damage occurred to blades, gears and bearings have been examined and the consequences analysed. The occurred failures are examined and the reliability of WTGs is assessed by appropriate models and analysis. The results are com pared to literature data and they may be very useful in programmable maintenance and in predictable one. Reliability analysis may be also useful to increase energy production.