Performance of Grain Augers

With the growing increase in the bulk handling of grain, the grain-auger type elevator is now being widely used. While some theoretical analyses of the grain auger have been made and performance data for particular size augers have been obtained, little information is available for general design purposes. This work, which is based on an experimental approach, is aimed at producing such information. The investigation has been carried out using a small scale model auger which allowed a comprehensive range of tests to be conducted on a more manageable basis In the first part of the investigation, a study is made of the auger performance characteristics with the aim of determining the conditions for most efficient operation. An examination is made of output and volumetric efficiency in relation to speed, angle of elevation and choke length (the length of exposed screw projecting from the lower end of the casing). The effect of casing clearance on auger output is also partially examined. In addition, the variation of auger horsepower and overall efficiency with speed and angle of elevation is observed In the second part of the investigation, equations are developed and design charts given which enable the performance of augers to be predicted. The equations and charts are based on the application of dimensional analysis and dynamic similarity and apply to augers of the same geometrical proportions as those of the model. The data apply mainly to granular materials of similar shape and properties to wheat. A comparison is made between the predicted performance with the actual performance of a 6-in. auger, good agreement being obtained The investigation shows that many combinations of auger size, speed and angle of elevation may be adopted for a particular conveying application and general recommendations are given regarding the choice of these variables for efficient operation