CHAPTER 3
                        CHARACTERIZATION OF FACILITY

    To characterize the wind and water tunnel test sections, the mean flow quality of both the sections and the influence of vibration of the fan and pump on the test section vibration are considered here. The mean velocity profiles of both the test sections are measured separately. For the velocity measurements, a pitot-static probe is used in conjunction with a differential pressure transducer. Vibration measurements are carried out by placing accelerometers at tentative vibration sources, namely the fan and the pump, and the mid region of the test section. The velocity profile measurement for the air tunnel is described below.

                          Velocity Profiles of the Air Tunnel

Experimental Set-up

    The experimental set-up for measuring the velocity profile of the air stream is shown in Figure 3-1. The pitot-static probe is inserted from the slot in the ceiling of the test section at a distance of 19 in. from the start of the test section. The mounting of the pitotstatic probe and the coordinate system defined are shown in Figure 3-2. To avoid the air water interface, the tunnels are isolated using a plexiglas cover. Along with the pitotstatic probe, two pressure transducers, Validyne P855A and a Heise HSQ-1 (Range: 0 15 in. H20), are used to measure the dynamic head of the flow. A T-junction is used to split the pressure lines from the pitot-static probes to connect to the Heise and the Validyne transducers. The voltage output from the Validyne P855A, in the range from

5 to +5 V DC, is read using a UIP 34970A integrating voltmeter.

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