Experimental and numerical investigation on leakage flow, bristle deflections, and oscillation characteristics of brush seals

The objective of this research is to delve into the leakage, deflection, and oscillation characteristics of brush seals. To achieve this, the flow characteristics of a brush seal were first analyzed through numerical simulation. Subsequently, a static brush seal test rig was utilized to measure the leakage performance and hysteresis characteristics of brush seals with varying geometric structures under pressure ratios ranging from 1.1 to 3.8. The deflections of bristle during operation were observed using an endoscope, and dynamic pressure sensors were employed to collect data on the airflow dynamic pressure in the free end area of bristles, facilitating the analysis of bristle oscillation characteristics. The results indicated that considering the parameters of this study, the leakage increases with the rise in pressure ratio and radial gap. The long front plate configuration was found to contribute to an increase in leakage. Specifically, under the three radial gap conditions of 0, 0.1, and 0.2 mm, the maximum leakage difference between brush seals with and without the front plate configuration was 4.9%, 4.6%, and 2.6%, respectively. The increase in radial gap and the existence of the front plate were observed to diminish the hysteresis effect of brush seals. At a pressure ratio of π = 2.0, the hysteresis indicator H for structures with a radial gap of 0.2 and 0.1 mm decreased by 45.5% and 63.6%, respectively, compared to the 0 mm gap structure. The existence of the front plate resulted in a 33.3% reduction in H compared to its absence. Additionally, an increase in pressure ratio and radial gap was correlated with an increase in brush oscillation frequency. Under identical pressure ratio conditions, brush seals with the front plate also exhibited higher brush oscillation frequencies than those without.