1. The facility has been designed to simulate the conditions of an actual pulsed jet. The air supply to the facility is equipped with an inline heater that can sustain a mass flow rate of 0.5 kg/s (1 Ib/s) at 700 K and 1035 kPa (150 psi). The proper heating of the flow allows matching the dimensionless parameters of Mach number, Reynolds number and Strouhal number of the simulated jet. A stagnation chamber with a flow chopper (a rotating disc with 6 circular openings) is used to produce the pulsed jet. The frequency of the pulses can be varied precisely up to 250-1 Hz by changing the rotational speed of the motor driving the chopper. As shown in figure 1a, the ejector coupled to a linearly free support, is attached to the nozzle for thrust measurement purposes. The rectangular ejector duct is of a fixed length (508 mm) width (150 mm) and a variable height (38.1 mm - 158.75 mm) giving the flexibility of having variable area. The ejector is designed with a super elliptic curve at the leading edge to avoid separation for increased performance as shown in figure 1b and 1c. The ejector is positioned in such a way tha
2. with time. seeded with sub-micron (~0.3 µm) oil droplets generated b to the main jet. The flow rate of the seeding particles was controlled in such a way that there were enough particles in the jet. The ambient air was seeded with smoke particles (1-10µm) produced by a Rosco fog generator. The necessary signal for the synchronization of the PIV system and the pulsed flow was obtained from an incremental optical encoder attached to the rotating shaft. The encoder had 720 increments in order to precisely mark the phase of the pulses. C. The Thrust Balance
3. As /Ap 0 2 4 6 8 10 12 14 16 18 20 0 Figure 18a. Typical Microphone Time Signal at M=0.80. time (s) 0 0.005 0.01 0.015 0.02 0.025 -150