Brush Seal Hysteresis

Abstract

The use of Brush Seals continues to expand in both the Power Generation and the Aerospace markets and we continue to learn more about their functionality. This paper continues on from our previous papers and in particular AIAA 2002-3794 which examines, analytically and experimentally the effects of Hysteresis. The 3D Finite Element Model has been developed further to more accurately predict the physics of brush seal hysteresis. This will be demonstrated by comparison of data from the model to test data gathered from manufactured seals tested in the laboratory. This model has full bristle-to-bristle contact, bristle to back plate contact, bristle to rotor contact and can be pressure drop loaded.

Theoretical and numerical investigation into brush seal hysteresis without pressure differential

“…The main reason can be that FEM divides the whole movement into many individual steps, neglecting the inertia. It is a pity that the comparison between the numerical results and the experimental results of rotor-down process was not presented by Demiroglu et al 9 Similar difference, especially in the rotor-down process, can also be found in the work of Chen et al 10 It is worthy to note the experimental results (figures 22 and 23) in the work of Crudgington et al 11 During the rotor-down process, a less inclined curve was presented which is similar to the present numerical results.…”

“…where K r is the bristle radial stiffness. K r is a quantity to evaluate the bristle stiffness in brush seal field and has already been adopted by previous studies such as the work of Crudgington et al 1 and Chen et al 10 K r in the present research is around 3872 N/mm . The geometry parameters are listed in Table 2.…”

“…However, their experimental results did not match well with the theoretical results. 1 With the development of measurement technology, direct force measurement for brush seals, which are subjected to pressure differential, has been achieved. Aksoy and Aksit presented a brush seal stiffness measurement.…”

“…The numerical model was validated by experimental results only for the case without pressure differential. 11 Duran et al developed an FEM brush seal model to analyze the stiffness by ABAQUS. Their model was able to obtain the hysteresis loop in the static (without rotor rotation), dynamic (with rotation), and pressured cases.…”

Flow Conditioning to Control the Effects of Inlet Swirl on Brush Seal Performance in Gas Turbine Engines

“…A number of approaches to modeling of mechanical aspects have been presented in the literature. Crudgington et al (2012) established a three-dimensional (3D) mechanical model to estimate the reaction forces and bristle deflection, showing that hysteresis and aerodynamic loading are the dominant factors for the sealing performance. Guardino and Chew (2004) and Lelli et al (2006) developed 3D computational fluid dynamics (CFD) and 3D bristle bending models for brush seals, demonstrating the potential to investigate bristle pack deformation under aerodynamic loading.…”