The most reliable and economic way to control fluid leakage from industrial equipment such as centrifugal pumps and mixers is to isolate the rotating shaft and its housing with a mechanical seal. These devices, though simple in concept, present a variety of engineering challenges to the designer.

Of particular concern is the thermofluid environment in which key components of the seal must operate. In order to protect critical parts and ensure functionality, heat caused by sliding friction is commonly removed by forced convection cooling. Experience shows that cooler operating temperatures correlate with improved, more stable performance, reduced wear, and extended life of the seal.

Visualizing Fluid Flow and Heat Transfer

in

Rotating Shaft Seals

Ray Clark and Henri Azibert

A. W. Chesterton Company

Stoneham, Massachusetts 02180

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Design concepts for improved fluid sealing were studied using advanced engineering analysis and state-of-the-art data visualization. Computational Fluid Dynamics (CFD) provided the principal means for evaluating the circulation and effectiveness of coolants used in dual mechanical seal. Virtual prototype tests were carried out using FLUENT, a general-purpose fluid flow solver. Laboratory measurements were also made to confirm the CFD results.

The simulations of flow behavior in seals were examined using IBM Visualization Data Explorer. Visual programs developed within the DX environment were used to display and extract important design information from large sets of three-dimensional multivariate data.

A particularly interesting and revealing aspect of the analysis involved flythrough animation sequences created from images depicting fluid particle trajectories. From an immersed, moving frame of reference the observer travels through the flow alongside data-mapped streamribbons. This technique has proven useful for identifying causal relationships between fluid motion and local flow variables such as temperature, static pressure, turbulent kinetic energy, and vorticity.

Conclusions drawn from the project suggest simple and cost-effective ways to enhance removal of heat, while improving the thermal environment, operation, and life expectancy of seals.