The paper presents the results of an experimental investigation wherein the bullet form drag force as a function of oscillating actuator frequency, various voltage and for different orifice/slot configuration are studied. In order to perform the experiment, an axisymmetric bullet shape model with ellipsoidal nose was used in wind tunnel. The synthetic jet actuator was used to flow control at sharp cut end. The experiment was conducted in a wind tunnel with a working diameter of 1000 mm and a maximum velocity of 45 m/s. The measurements were carried out for the Reynolds number from 88000 to 352000 and for relatively large Strouhal numbers up to St = 4.5 based on model external diameter and free stream velocity. While synthetic jet was switched on, drag coefficient has been reduced by-6% and increased by +22% in relation to the case with the synthetic jet was switched off. The synthetic jet has more impact for relatively low free stream velocity and for single axisymmetric orifice.
The acoustic and flow aspects of the novel synthetic jet actuator (SJA) with fins inside the cavity were experimentally investigated for three types of enclosure design and two models of loudspeaker. The aim of the study is to find the parameter which connects the flow and acoustic properties of the SJA and allows us to choose the optimal solution in those regards. The hot wire anemometry was used for the velocity measurements and the sound pressure level was measured with a sound level meter. The model of the loudspeaker turned out to have a significantly stronger impact on the flow parameters and noise level than the shape of the fins in the cavity. The parameter that showed a dependence on the shape of the fins was the actuator’s efficiency. A ratio of the root-mean-square velocity at the orifice axis to the sound pressure level (U0.c/SPL) was used to connect the acoustic and flow properties of the tested actuators. This parameter was subsequently applied to determine the best configuration among the tested actuators.
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