CoursHeroTranscribedText: Q48. Hopper design Intermittent ow is experienced from a cylindrical silo with a conical hopper that is several years old. The design criteria have been checked by re-measuring the powder properties and wall friction. The powder properties were found to be unchanged but it was discovered that the hopper wall had become badly scored. Using the following data and gures determine what minimum diameter opening is now required. Powder characteristics: Bulk density: 1800 kg/m3, angle of internal friction is 500 Unconfined yield stress (kPa) 8.5 5.8 3.0 Maximum consolidation stress (kPa) 16.0 10.0 3.5 40 Core flow 30 1.2 20 Off= 1 .3 Angle of wall friction, degrees. 1.6 10 2.025 1.4 1.8 4.0 3.0 Mass flow O 30 40 50 O 10 20 Hopper slope from vertical, OH. Fig. 10.19 Jenike design chart for a powder with an effective angle of internal friction of 50 Wall friction results In 1998 Normal stress kPa 8.00 4.00 2.00 In 1998 Shear stress kPa 1.41 0.71 0.35 In 2002 Normal stress kPa 8.00 4.00 2.00 In 2002 Shear stress kPa 3.23 1.62 0.81 Hopper half angle is 150