Re: Apron Feeder
My understanding is that
Hydraulic Radius = 2 x Cross Sectional Area / Perimeter ■
Re: Apron Feeder
Thanks for your reply.
What I want to know, is in a given drawing of Hopper , which is the portion that constitutes ' Hydraulic Radius ' ? I mean , what is the definition?
Baiju Joshi. ■
Re: Apron Feeder
For a non-circular section the hydraulic radius is a 'notional' value.
In the case of a circular hopper outlet the hydraulic radius is equal to the hopper outlet radius.
In the case of a rectangular outlet of sides a & b
hydraulic radius = (a x b) / (a + b) ■
Re: Apron Feeder
Dear Shree Joshi,
In general, the hopper comprises of vertical portion and bottom converging portion.
While designing the belt feeder or apron feeder, one has to find out the material pressure at the outlet of the hopper i.e. at the lower end of converging portion of the hopper. The pressure at the hopper outlet is also depending on the material pressure in the vertical portion of the hopper. Therefore, firstly one has to calculate the material pressure at the interface of "vertical portion and converging portion". The material pressure in vertical portion is calculated by Janssen formula wherein the certain values are conveniently expressed as hydraulic radius. So, this term is applicable for pressure calculation for vertical portion.
Subsequent to this, one has to use the formula for calculation of pressure in converging portion of hopper. In this pressure calculation, the material vertical pressure "at the interface of vertical section and convergent section", becomes the input to the formula for converging portion. Using the formula for convergent portion, calculate the pressure at the outlet of the converging portion. This pressure is conveniently expressed as material column load (i.e. hypothetical material column height as if freely standing at the outlet and creating same pressure as it actually occurring.
As said above, you have to also use the one more formula which is other than the formula mentioning the hydraulic radius.
Regards,
Ishwar G Mulani.
Author of Book : Engineering Science and Application Design for Belt Conveyors.
Author of Book : Belt Feeder Design and Hopper Bin Silo
Advisor / Consultant for Bulk Material Handling System & Issues.
Email : parimul@pn2.vsnl.net.in
Tel.: 0091 (0)20 25882916 ■
Re: Apron Feeder
I am sorry for not being able to revert earlier, due to a site-visit.
I thank the 'Designer' and Shri I. G. Mulani for their replies.
Further on the topic and to complete my calculations to determine the resistances, I need to know the numerical value to factor K in the following formula :
Resistances due to column load = (hopper opening x hydraulic radius x Bulk Density x 1000):-(K x co-efficient of the internal
friction of the material)
From what I gathered , I think K is not less than 1. And, co-efficient-constants vary in different literatures / books.
Kindly, also let me know what is the factor K?
Baiju Joshi. ■
Re: Apron Feeder
Originally posted by Baiju Joshi
I need to know the numerical value to factor K in the following formula :
Resistances due to column load = (hopper opening x hydraulic radius x Bulk Density x 1000):-(K x co-efficient of the internal
friction of the material)
From what I gathered , I think K is not less than 1. And, co-efficient-constants vary in different literatures / books.
Kindly, also let me know what is the factor K?
Baiju Joshi.
Since I have no idea where your formula came from I am unable to comment further.
You need to ask the guy who wrote the formula! ■
Re: Apron Feeder
The formula is from 'Deevski' and even I can't figure out where to contact him.
Baiju Joshi. ■
Apron Feeder
While calculating resistances due to column load of material on an Apron Feeder, I have come across a term called ' Hydraulic radius of the hopper section opening '. I want to know , what is it ?
Baiju Joshi ■