Abstract
Tests were conducted to find the effects of container diameter and air travel distance on the resistance to air flow through cut orchard grass hay.
To find the effects of the container diameter, hay samples were packed into the container of 7.7-80cm in diameter to a depth of 30cm, and to find the effects of the air travel distance they were packed into the container of 7.7cm in a diameter to a depth of 180cm.
1) The general equation for airflow through hay is
P=10-uLSvdmVn
where P: pressure drop, mmAq
L: distance of air travel through material, m
S: container diameter, m
d: apparent density, kg/m3
u: exponent
v: diameter exponent
m: density exponent
n: velocity exponent
2) Exponents u, v increased slightly as moisture content increased. For 20-60% moisture content, exponents u, v of first cutting hay were 1.268-1.800, 2.857-4.911 and second cutting hay were 0.789-0.978, 4.040-6.067 respectively.
3) Density exponent m increased as moisture content increased and the container diameter decreased. For 20-60% moisture content and 1m container diameter, exponent m of the first cutting hay was 1.599-4.791 and that of the second cutting hay was 1.448-1.635.
4) Velocity exponent n increased as moisture content increased and apparent density decreased. For 20-60% moisture content and 100-300kg/m3 apparent density, exponent n of the first cutting has was 0.907-1.301 and second that of the cutting has was 1.271-1.401.
5) Airflow resistance was nearly proportion to air travel distance L and container diameter S.
