Session: 01-09 Modelling, Simulation and Validation I

Paper Number: 151886

Analysis and Comparison of Hydrodynamic Features in Liftoff Seals 

Dynamic seals are often used in the aerospace industry for sealing fluids in gearboxes, turbo pumps, engine main shafts, and industrial compressor applications. Dynamic seals consist of two pieces, a rotating mating ring (rotor) that is attached to the shaft and a static, non-rotating carbon face (stator). During operation, the mating ring rubs against the carbon element, generating heat from friction and the environment. In applications where temperature, leakage, or life requirements demand higher performance, hydrodynamic liftoff seals are generally employed. Mating rings are designed with features on the contacting surface that enable the development of a film of oil and air between the mating ring and carbon seal face above certain operating speeds. This film significantly reduces the heat generated from friction compared to a contacting face seal as there is no contact between components when liftoff is achieved. 

There are multiple ways to design and manufacture a hydrodynamic liftoff seal. A major part of the manufacturing of such seals consists of two proprietary processes used to manufacture the hydrodynamic features. These processes will be referred to as process A and process B. Process B is a relatively fast and inexpensive method for creating features, but generally reduces the amount of customization that the surface shapes can be designed to have. Process A is a slower process, but it allows finer geometric control of the features. This work aimed to characterize the performance differences between these two types of hydrodynamic features manufacturing methods by studying the speed at which the seals liftoff, the film stiffness that the seal rides on, the operating temperatures, and resultant seal leakage. Four mating ring designs were tested and included seals designed for process A which were manufactured using both processes, and two more seals designed for process B, and which were manufactured using both processes.  

These experiments showed a direct correlation between liftoff speed and film stiffness. This means that seals that lifted off at lower speeds generally exhibited lower film stiffness. The chosen manufacturing method, process A or B, has a relatively large impact on seal performance (operating temperatures, liftoff speed, and film stiffness). Seals designed for a particular process performed similarly with both manufacturing methods.  

Presenting Author: Stefan Roeseler Technetics Group

Presenting Author Biography: R&D Design Engineer at Technetics Chicago.

Authors:

Stefan Roeseler Technetics Group
Aaron Glafenhein Technetics
Todd Adams Technetics
Miguel Rodriguez Technetics
Justin Baldauff Technetics
Ryan Plessinger Technetics
Erin Volpe Technetics
Elaine Motyka Technetics
Tyler Noyes Technetics
Becca Jones Technetics
Shannon Depratter Technetics
Jonathan Kweder Technetics