刷式密封吹下效应诱发机理流固耦合数值研究

分析了刷式密封吹下效应理论模型,建立基于arbitrary Lagrange-Euler(ALE)流固耦合方法的刷式密封吹下效应三维瞬态数值模型,在验证数值模型准确性的基础上,分别研究了刷丝轴向、径向和截面变形特性,量化分析了刷丝径向吹下量,揭示了刷式密封吹下效应诱发机理.研究表明:刷式密封吹下效应会减小刷丝径向间隙,...

Numerical investigation on induced mechanism of blow-down effect of brush seals with fluid-structure interaction

The theoretical model of blow-down effect of brush seals was analyzed. The three-dimensional transient numerical model of blow-down effect of brush seals based on arbitrary Lagrange-Euler（ALE） fluid-structure interaction method was established. The axial, radial and sectional deflection characteristics of bristles were studied respectively. The radial blow-down displacements of bristles were analyzed quantitatively, and the induced mechanism of blow-down effect of brush seals was revealed. The results showed that the leakage can be calculated more accurately with consideration of blow-down effect, because the bristle radial clearance was reduced by blow-down effect. Blow-down effect of brush seals presented an unsteady deflection with bristle oscillation. Compared with bristle cross section in the radial middle and end position of backing plate, blow-down effect and bristle oscillation of bristle tip were stronger. Bristles had more radial blow-down displacements and stronger bristle oscillation with the increase of inlet-outlet pressure ratio. When the inlet-outlet pressure ratio was 2, 3 and 4, the maximum radial blow-down displacement of bristles in the middle of bristle pack was 0.004, 0.010 mm and 0.019 mm, respectively, under the studied condition. The initial condition for the bristles with a certain circumferential lay angle and the radial pressure gradient in bristle pack contributed to the induced blow-down effect, and blow-down effect was further influenced by the normal pressure and the tangential friction between bristles. Blow-down effect of brush seals can be weakened by increasing the circumferential lay angle.