Aerodynamic investigation of the Cour's pollen filter

Abstract

At the Department of Physical Geography, Göteborg University, the Cour's pollen filter was used to calculate the aerial mass flow and concentration of marine salts in coastal and inland locations. During this work, it became apparent that a correction formula for obtaining the flow through the filter was required. This was obtained by acquiring correct concentration values from the flow through an undisturbed, equally-sized cross section beside the filter. Cour (1974) suggests that concentration values should be multiplied by a factor of five but also adds that the relation is wind speed dependant. Hence, an aerodynamic investigation was performed in a wind tunnel at five different reference wind speeds. The air flow through the filter was thus found to depend on reference wind speed as a 4th grade polynomial. The airflow through the filter is insignificantly affected by applied contamination of wheat flour or pollen grains to the filter surface up to approximately 500 mg. Above is an increasing risk for reduced flow. The reduction can be estimated using the results of this work. Applying the correction to existing data showed that the correction effect decreases with increasing reference wind speed. Due to the form of the polynomial, a correction is not recommended outside the approximate interval 2 27 ms−1. © 1998 Taylor & Francis Group, LLC.