The directivity of wind turbine noise is of widespread interest and has received attention over an extended period. The reason for this is partly that noise optimization procedures can be implemented in order to increase the efficiency of the power output. Although directivity of horizontal axis wind turbines (HAWTs) are well understood, the directivity pattern around vertical axis wind turbines (VAWTs) are less well investigated.This paper presents measurements of directivity on a 200 kW VAWT, a so called H-rotor, with variable speed and a tower height of 40 m. The turbine, which is situated in a flat agricultural landscape close to Falkenberg at the Swedish west coast, is one of the world’s largest today operational VAWTs. Experimental results as well as a theoretical model based on the turbulent-boundary-layer trailing-edge (TBL-TE) noise suggest higher noise levels upwind of the rotor and the lowest noise levels in the perpendicular directions. Moreover, modulation analysis of the measurements indicates the presence of modulations but the results are inconclusive.

Initial noise measurements were performed on a 200kW vertical axis wind turbine (VAWT) and results were compared to that of a Vestas V27, a similar size horizontal axis wind turbine (HAWT). Multiple recording units were placed in line downwind of the turbine to investigate noise propagation. The frequency distribution of the noise were analyzed indicating that the VAWT has lower relative levels for frequencies under 3000 Hz, especially within 600-1200 Hz. Furthermore, VAWT noise seems to occur more around the same frequencies as the natural background noise, increasing masking probability. Results from propagation measurements seemed to indicate that noise declines more rapidly with distance for the VAWT then for the reference HAWT, possibly explained by the lower levels at low frequencies. Further investigation is needed to establish these differences and the 200 kW VAWT creates an opportunity doing so utilizing arguably the largest operational VAWT existing today.

It is a constant challenge for the automotive industry to reduce friction losses and oil consumption in automobile engine. The piston ring friction accounts for approximately 20% of the total mechanical energy losses in a modern engine. Oil control rings limit and control the oil consumption of the engine as well. They scrape off excess lubricating oil from the cylinder walls and return it to the crank case. Piston rings are designed to distribute the thin oil film evenly to ensure piston and ring lubrication. The surface topography of a piston ring is an efficient variable in the control of the oil consumption and friction losses. In places where the interacting surfaces come in contact, the oil film thickness is extremely thin and the surface asperities may deform because of the high pressures. There are different types of oil control rings.The most common one is the twin land oil control ring, which consists of two narrow lands that scrape off the oil on the liner and a spring on the back that exerts the load. In this paper, the surfaces of the two lands were investigated, since they play the key role in its function. The goal is to map the variation in surface roughness of piston rings that appear at different scales from form and waviness to micro and nano roughness. Areal topography measurements were made by white light interferometer designed at the Halmstad University able to measure and scan the total functional area of a piston ring. An significant amount of oil control piston rings of heavy duty truck engines were examined and 24 measurements were made in circumferential direction and on each ring land. The results show both the variation and uncertainty of the ring topography and discuss the instrument and measuring methodology uncertainty. The most stable parameters were found and recommended for an effective quality control. Comparisons between established coherence scanning interferometer and the instrument built in Halmstad were made. To ensure a good quality, the measurements were made both on calibration standards and on piston ring surfaces. Finally the influence on function and energy losses in the final engine assembly is discussed to indicate future design and metrology improvements.  

This paper presents observations of audio noise in frequency range 20e20 000 Hz from wind turbines. The observations were performed around the theoretically calculated 40 dBA noise perimeter around the wind turbine farm at Oxhult, Sweden. This paper describes a newly designed and constructed a field qualified data acquisition system to measure spectra and total noise level of sound from wind turbines. The system has been calibrated at SP Borås. It is shown that it has a flat frequency response and is linear with amplitude and time.

The total noise level (as integrated 20e20 000 Hz) is shown to be below 35 dBA (below the reference background noise at 36 dBA) at a 10 m altitude wind speed of 4e5 m/s. The measurements were made along the theoretical 40 dBA border at 8 m/s.

It is concluded that the theoretical 40 dBA border seems reasonable calculated if the manufacturer specifications are used to extrapolate the sound level to correspond to 8 m/s at 10 m. Our data indicate that a simple sound propagation model is sufficient since the sound level is more affected by the nearby environment than the large scale forest structure. Also, the large scale forestry structure is bound to change with time and the error bars of measurements on total sound level are about 1 dBA, which is larger than any fine tuning with a more sophisticated model. More care should be taken to model the reflections from walls and other obstacles close to the microphones.

The distribution of the spectral noise level around the turbine farm suggests that the noise originates from individual wind turbines closest to the measurement location rather than from the wind turbine farm as a whole. The spectra show narrow band spectral line features which do not contribute signifi-cantly to the total noise at this level. The narrow band features are only detectable at very long inte-gration time and at 1 Hz spectral resolution. The spectral features are typical to originate from mechanical noise.

The spectral acquisition method described in this paper can be used as a field qualified system for sound measurements in forest areas. The high spectral resolution is a viable remote diagnostic method for mechanical faults in the turbine machinery. Future work will concentrate on these two areas.

The customer’s demands for higher quality, faster delivery times and reduction of cost, give evidence for the need to develop new technologies or enhance existing technologies combined with research activities.

The automotive industry's capability to develop new products in a shorter time is constantly improved.  Tool and die creation is a major part of the product creation for many industrial products and in particular for the automotive industry.  The higher product requirements on reduced weight, better safety, and lower emissions have meant that a larger number of automotive body parts must be made in advanced high strength steels.

Improved functionality of surface textures and engineered tailor made component surfaces is one enabling technology for industry to increase compete ability by improved component function and reduced friction losses.

However, material properties’ variation, un-evenly spread wear, unknown manufacturing process variations, the ”human factor”, faulty metrology procedures …   All factors interact to increase the problems of utilizing surface texturing on the micro metre level as a competitive tool for industry.

Large variation of the micro topography created by industrial machining processes tends to reduce the impact of the usage of improved engineered surfaces on critical components.

A proposal of a strategy for metrology using "intelligent" sampling techniques comprising of regionalization of the functional area and designed sampling patterns is presented.

To efficiently make use of efficient sampling, an example of a recently developed optical scattering light in-line metrology of high precision surfaces is discussed as a tool to enable efficient control of machine tools in general.

Future steps discussed include developing of control loops for implementation in CNC controllers to efficiently make use of the "smart" surface texture characterisation data from the developed in-line surface texture sensors.

Polymer optics is a growing market both for medium quality optics and precision optics. Steel moulds for polymer optics are normally produced in several process steps; the last step before moulding is manual polishing. This step requires skilled experts and is very time-consuming. The focus of this paper is on robot polishing of steel moulds for polymer injection moulding of optics. The goal of this work is to replace manual polishing and other process steps with robot polishing. Therefore a new process has been developed to minimize the number of required process steps.

Steel moulds for polymer optics demand high standards of roughness and shape accuracy. To reach the required specifications concerning roughness and shape accuracy different measurement and characterization methods are necessary. A combination of parameters determined with different measurement instruments is needed to validate the polishing results.

This project was started by Aalen University and UVEX Safety Group together with the Experimental Ophthalmology Group Homburg/Saar. The goal for this new process is to produce a ready to use steel mould with a shape accuracy better than 4µm and a micro roughness of less than 5nm rms; with just one process step after grinding.

There is an increasing requirement from manufacturing industries for improved technologies to measure surface topography. New instruments have to be accurate; robust to be used on the industry floor; non-invasive; automatic; and sufficiently fast to be used in real time as well as to simultaneously measure over a large area. The industrial applications are plenty:

• On-line quality control of machined parts,
• Direct feed back to the manufacturing process,
• Analysis and selection of surface texture/structure.

This paper presents new developments in interferometer techniques for new robust area-based topographic instruments.