During this period, I sought better ways to teach the technology. Prompted by adult-student struggles, I developed ways to make the study more enjoyable. For example, a major principle in the art of Instrumentation is the study of flow.
- Measure the flow
- Compare the measured flow with what is desired, and
- Make corrections to bring the Measured to the Desired value.
This 3-step process underlies all of Instrumentation! So, how do we measure Flow?
The setup here shows gas flow in a tube with varying diameters, A and B. The question: “In what section will the pressure be highest, A or B, when the flow is turned on?” The small tube between points A and B, a Venturi tube, with a colored liquid, shows any difference between Pa and Pb. The liquid level is the same, no pressure difference, when the flow is off as shown in Fig. 4.1.
When the flow is turned on in Fig. 4.2, the pressure is higher in the larger tube. The kinetic energy of the gas at point A has increased with its greater speed. To compensate for this change, gas pressure must decrease, as shown by the changed level in Fig. 4.2
FIg. 4.1 & 4.2 Pressure vs. Flow
Now that is all well and good, in theory, but to punch the principle home, we created a lab demo as shown next. We place a standard air conditioner fan near the door of the lab in position to blow straight up, with a beach ball resting on the fan.
FIg. 4.3 Position of the beach ball with the fan on and off.
Reason suggests the ball will blow away when the AC is turned on, but Viola! It merely hovers in place as shown in Fig. 4.3. What is remarkable here is the ball remains in the flow, even if we punch the ball, moving it out of the flow. It is pulled right back, where the pressure is least (we call that a vacuum). Nothing gets student attention quite like this, when asked to explain why the ball pops back into the flow. Others come into the lab just to see this phenomena. My students are happy to explain. This is the same action used by some carburetors to inject gas into the engine. It is also why a twister or cyclone sucks houses and cars into its center. During this time there was interest in the literature about the domains of learning: Cognitive, Psychomotor, and Affective. What jumped out at me was the attention on the affective.
a) Cognitive is recognition, the brain and its role in solving mental tasks.
b) Psychomotor is the physical, eye/hand coordination tasks.
c) The Affective domain deals with how the student feels about the learning activity.
I related well to the first two, but had no idea how the affect worked. What I learned, ‘practicing’ with my adult instrumentation students, was that the affective was a powerful and very important domain… and the least understood. Folks in the sciences and math seemed to avoid the affective domain, since their areas are not emotional. What a waste! Play around with a fan/ball setup like shown above and see how very emotional it can be. The students love it and come back for more… Let’s call the Affect, the first of many SECRETS…