Jet Impinging on an Inclined Plate

1. Setting the facility

1. Make sure that there is no flow in the facility.
2. Set the instruments according to the schematic in figure 2.
3. Adjust the plate to the desired angle . Record this value in table 1.
4. Measure the jet nozzle width W. Record this value in table 1.
5. Measure the plate span L. Record this value in table 1.
6. Zero the pressure transducer.
7. Note the calibration constant of the pressure transducer, m_p (Pa/V). Record this value in table 1.
8. Connect the high-pressure port of the transducer (marked as +) to the pressure tap of the plenum (marked as ).
9. Since all the operations take place inside the receiver, leave the low-pressure port of the transducer (marked as -) open to sense the pressure in the receiver ().
10. Start the flow facility (FLL).
11. Use the digital multi-meter to record the voltage (V) associated with the pressure difference between the plenum and the receiver sensed by the pressure transducer. Record this value in table 2.
12. Use the calibration constant m_p from 1.7 to determine the pressure difference between the plenum and the receiver (). Record this value on table 2.

Figure 2 . Details of data acquisition system. Schematic for equipment connections. Please click here to view a larger version of this figure.

Table 1 . Basic parameters for experimental study.

Parameter	Value
Jet nozzle width (Wn)	41.3 mm
Plate span (L)	81.3 cm
Plate height (H)	61cm
Transducer calibration constant (m_p)	137.6832 Pa/V

2. Running the experiment

1. Connect the high-pressure port of the transducer (marked as +) to the common port of the scanning valve. Leave the low-pressure port of the transducer (marked as -) open to sense the pressure in the receiver ().
2. Home the scanning valve to start your measurement from the first pressure tap position.
3. Run the Traverse VI (LabView virtual instrument).
4. Input the calibration constant m_p in the VI.
5. Set the sampling rate to 100 Hz and the total of samples to 500 (i.e. 5 seconds of data).
6. Enter in the VI the position () of the pressure tap from which plate-pressure data will be acquired. Take into account that the pressure taps are spaced by 25.4mm. Hence, the position will be mm, where is the index of the tap starting at 0.
7. Record the data. The VI will read the pressure difference between the pressure tap and the receiver (.
8. Step the scanning valve to the next tap position.
9. Repeat steps 2.6 to 2.8 until all the pressure taps are traversed.
10. At the end, the VI provides a table and a plot of tap position vs pressure.
11. Stop the VI.
12. Change the position of the flow control plate to close the flow area roughly by half (see Figure 3 for reference). This will modify the flow rate. Use Equation (5) to determine the value of this flow rate.
13. Repeat steps 2.3 to 2.11 for the new position of the flow control plate.
14. Modify the angle of the impingement plate and set the flow control plate to its initial position.
15. Repeat steps 2.3 to 2.14 for 80^o, 70^o, 60^o, 50^o, and 45^o.

Figure 3 . Experimental setting. Test section. Left: Impingement plate in front of slit. Higher-pressure air is discharged from the plenum into the receiver through this slit. Middle: pressure taps connected to the impingement plate are distributed into the scanning valve to sample one at a time. Right: impingement plate in front of receiver discharge. The discharge has a perforated plate to regulate flow rate. Please click here to view a larger version of this figure.

3. Analysis

1. For each inclination angle, plot the pressure data for both flow rates.
2. Use the experimental data to estimate the force on the plate based on equation (2).
3. Determine the jet velocity at the vena contracta using equation (3).
4. Estimate the mass flow rate using equation (5).