Hydraulics experiments - Carleton laboratory

Experiment 1: Laminar flow table

• the dyes on the laminar flow table are indicative of the streamlines (streamline = a path defined by the motion of fluid elements in a flow; at any point along a streamline, the flow direction is tangent to the streamline. Conceptually, water may not cross streamlines.)
• the density of streamlines is proportional to the flow velocity
• observe and note the flow line patterns around the obstructions (Fig)
• what conclusion can you draw in terms of pressure and flow velocity, considering that Bernoulli's law is valid for this situation: u²/(2*g) + z +p/(r*g) = constant?
• is there evidence for turbulent flow  (Fig)
• where in the real world can you find situations like the ones shown here?

Experiment 2: Discharge measurements using control structures

• the height behind a weir is related to the discharge rate by the equations given below

• determine the geometry of the weir and measure the relevant parameters
• measure Q as a function of H for 5 different settings for one of the weirs  (Fig)
• enter the data in Google doc
  
• Some of the results of this exercise will be subject of the next homework.
• previous year's data (channel_lab_sum.xls)

Experiment 3: Bernoulli's law

• Bernoulli 's theorem states that along a streamline:
• u²/(2*g) + z +p/(ρ*g) = constant and the flow rate in a pipe is Q=u*A (A is the cross sectional area of a pipe).

• The experimental set-up  includes a transparent horizontal pipe that decreases from a diameter of 25 mm to a minimum diameter of 10 mm and then increases back to a diameter of 25 mm. The changes in pipe diameter are achieved via tapered sections. The converging section has a smaller angle that the diverging section.
• Manometer tubes are attached at different locations along the pipe. The entrance to these tubes is perpendicular to the direction of flow. Thus, the tubes measure the piezometric head (p/(ρ*g) + z) at a specific location. A total head probe can be inserted into the pipe to measure the total head (u²/(2*g) + z +p/(ρ*g)) at different locations within the pipe.
• Make sure the apparatus is level. Check that the manometer tubes do not contain air-bubbles as this will distort the readings.
  
• Use the top of the base-plate upon which the apparatus rests as a datum (z=0). Measure the elevation of the horizontal centerline of the pipe above this datum as well as the elevation of the zero scale for the manometer tubes above this datum.
  
• Carefully adjust the inlet feed and the flow control valve on the outlet of the apparatus so that the water in the manometer tubes rises as high as is reasonably possible.
  
• Note the scale reading on each tube. Find the flow rate through the pipe, Q. by takjng the average of three sets of volume and time measurements. Use the tank 's volume measurement system for this. Insert the total head probe into the pipe and measure the total head at each location where a manometer tapping is measuring the piezometric head.
• Repeat the procedure outlined in the above paragraph for two flow rates in total. Flow rates can be adjusted using the outlet flow control valve. Try to obtain a reasonable change in the manometer heights between the different flow rates.
• Enter the data in the Google document.
  

• Pictures of the Carleton activities (Fig)
• Thin Plate Weir Stage Discharge Relationships