| Abstract | The ultrasonic method of measuring sand size distribution and concentration is based on the attenuation of an ultrasonic plane wave due to the presence of suspended particles in water. It attempts to meet the need for accurate and automatic instrumentation for studying
the sediment loads of artificial open channels and alluvial streams. The energy loss mechanism consists of four ranges each characterized by the relationship of the particle circumference to sound wave¬
length. The transition loss range (1.50 < ⫪dg /λ < 12.50) was found to be the most significant in the measurement of sand sizes where the geometric mean size, d is from 100 to 500 microns, It was studied using dimensionless plots of Of αλ vs. ⫪dg/ λ known as standard ultrasonic curves which were derived by numerical integration of the attenuation relation.
In this study, empirical relations that were derived in proceeding
investigations are presented in graphical form. Verification measurements by ultrasonic, sieve, and visual accumulation tube, using 23 sand samples, showed good correlation. With sieve as standard, the results
are comparatively close considering errors of measurement, sampling, and curve fitting, except the geometric standard deviation measured by the V.A. tube which was found to be less than that of the ultrasonic technique. For the geometric mean size determination, the average
deviation from the sieve standard is 5.24% for the ultrasonic analysis, and 3.43% for the V.A. tube; for the geometric standard deviation, the ultrasonic average deviation is 4.03%, and for the V.A. tube, 4.40%. In conclusion, the ultrasonic method compares favorably with sieve and V.A. tube analysis for sand size distribution including the range
of sizes from 0.044 to 1.00 mm. Furthermore, the electronic apparatus is subject to considerable improvement which would in turn increase the ultrasonic measurements accuracy considerably |
