Potentiometer and Iris Valve Analysis for Flow Rate and Diameter

This assignment delves into the analysis of a mechanical system involving a potentiometer and an iris valve. The student has provided a detailed analysis, including the calculation of flow rate and diameter based on potentiometer settings and valve positions. The assignment includes sample calculations, such as determining the percentage of open diameter in the iris valve and calculating the flow rate based on pressure drop and potentiometer settings. The data presented showcases the relationship between the potentiometer settings, the iris valve's open diameter, and the resulting flow rate. The student's observations suggest a linear relationship between the flow rate and the percentage of open diameter, with variations attributed to the estimation of velocity from a nomogram. This assignment is a practical application of engineering principles, demonstrating the student's ability to analyze and interpret experimental data. The assignment aims to understand how the iris valve controls the flow linearly with respect to % open diameter and provides the reader with the ability to understand how to calculate the flow rate of the valve.

Potentiometer
Setting
∆h
(mm)
∆P
(N/m2)
Air
Flow
(dm3/s)
%Valve
Opening
Diameter
2 4 39.2
2 4 39.2
2 3 29.4
2 3 29.4
2 2 19.6
2 1 9.80
3 8 78.4
3 8 78.4
3 7 68.6
3 7 68.6
3 5 49.0
3 3 29.4
4 15 147.0
4 14 137.0
4 13 127.0
4 12 117.0
4 9 88.2
4 6 58.8
5 22 215.6
5 21 205.8
5 20 196.0
5 18 176.4
5 15 147.0
5 10 98.0
6 31 303.8
6 30 294.0
6 29 284.2
6 27 264.6
6 22 215.6
6 15 147.0

20 30 40 50 60 70 80
0
20
40
60
80
100
120
140
160
E) Iris Valve Characteristics
2 3 4 5 6
% Open diameter
Flow Rate in lit/s
Legends 2, 3, 4, 5, 6 are potentiometer settings for the blower.
Sample Calculations:
1) Calculation of % Open Diameter in Iris valve:
For position 2 of the valve,
d = 47.5 mm. Fully open diameter = 80 mm.
Therefore, % open diameter = 47.5/80 = 59%.
2) Calculation of Flow rate in Iris Valve:
For potentiometer setting of 6 and the iris valve position of 5, ∆h = 36 mm.
As explained in 1) above, 36 mm WC = (36*9.8) = 353 Pa.
For line number 5 at 300 Pa, flow rate is about 95 dm3/s. So, using judgement, for
353 Pa, the flow rate would be close to 100 dm3/s.
Comments:
The % flow-rate is generally falling in a straight line with respect to % open diameter.
The variation is due to estimating velocity from nomogram. Thus, the Iris valve
controls the flow linearly with respect to % open diameter.