Low-speed flow oscillations in a cavity with slanted front and aft walls

An experimental study was performed to examine the effects of slanted aft and front walls on cavity flow dynamics. Experiments were conducted at a free-stream velocity of 26 m/s using a cavity with a length-to-depth ratio of 3. Unsteady and time-averaged pressure measurements across the cavity span were used to assess the impact of slant angles of 15°, 30°, and 45° on the frequency spectra, with a rectangular cavity serving as a baseline. The baseline case showed dominant oscillation frequencies in line with Rossiter’s feedback mechanism. For the 15° slant angle, cavity oscillation frequencies were present but with reduced amplitudes and deviations from Rossiter’s equation. At a 30° slant angle, the spectra revealed a broadband peak of high amplitude, whereas the 45° slant angle suppressed oscillation peaks, indicating the absence of the feedback mechanism. Noise analysis indicated that the overall noise was highest for the 30° case, lower for the 45° case, and similar to the baseline for the 15° slant angle, with a slight increase noticed near the leading edge. The results underscore the role of slant angle in modulating cavity oscillations and noise, suggesting that the 30° cavity may be better suited for broadband energy harvesting due to its broad frequency response.