In 1934, based on wind tunnel tests, Woelfle developed a shield similar to the Nipher.
The Woelfle windbreak ring is equipped with vertically arranged circular metal louvers. These louvers are fixed and converge at the base of the rain gauge. The individual louvers are connected by a ring.
The Woelfle windbreak ring consists of:
· Standpipe for the rain gauge
· frame
· metal slats
· small parts for assembly
1. Messhöhe
The existing foundations and threaded studs on the measuring field are used for installation.
The windscreen is made of V2A 1475 stainless steel. A lifespan of 10 years can be guaranteed under average meteorological conditions. This guarantee cannot be given for use on islands.
2. Structure
2.1. The Ring
The Woelfle windbreak consists of 21 circularly arranged metal slats, each 35 cm long. The metal strips are trapezoidal and U-shaped.
The arrangement on the circle with a diameter The 1060 mm spacing is achieved at equal intervals using slots.
This also ensures that the metal slats can be easily replaced.
The louvers are arranged in a fixed vertical position. This prevents the louvers from becoming blocked at high flow speeds, depending on the direction of the flow and the wind speed.
3. Modifications
The aerodynamic shaping of the upper ends of the metal lamella is done at an angle of almost 90°.
4. Maintenance
To facilitate maintenance of the rain gauge, one element of the ring is designed to be hinged. This element is secured with wing nuts and can be removed without tools.
5. The frame
The supports are at a 120° angle The supports are staggered and taper conically towards the foundation base. They are fixed in place using the pins already present in the foundation.
The supports and all connecting components are made of V2A stainless steel. The entire structure is also height-adjustable at the supports. This allows the system to be releveled and adapted to the requirements of the measuring point.
6. Other
The windscreen can be retrofitted with a bracket for an anemometer to correct the precipitation values.
