info: The Superpipe Facility

An experimental facility has been constructed to investigate a fully developed turbulent pipe flow over a large range of Reynolds numbers. This wind tunnel is called the Princeton/DARPA-ONR SuperPip Facility, and it uses air at pressures up to 3,500psi as the working fluid In the past many experiments (Nikuradse, 1932; Laufer, 1954 and Townes et al., 1972 to name a few) have been performed on a fully developed turbulent pipe flow because of its simplicity and industrial importance. However, despite the vast amount of data in publication it is difficult to find satisfactory agreement (on friction factor and turbulence intensities for example) between investigations or to find data at very high Reynolds numbers where many industrial systems operate. All of these investigations are lacking in some respect due to either a limited range of Reynolds numbers investigated, an uncertainty in the quality of the inner pipe finish, a questionable accuracy of the measurements, or a lack of experimental proof that the turbulence is fully developed. In the design of the Superpipe, particular attention was paid to the question of obtaining fully-developed flow (L/D = 200, with an internal diameter of 5.09in), and achieving a smooth-wall finish (roughness less than 6 microin). Therefore, we believe that the Superpipe allows very accurate measurements over a large range of Reynolds numbers, from approximately 5,000, to more than 38,000,000, corresponding to an order of magnitude increase over the highest Reynolds number for mean flow measurements (Nikuradse, 1932), and almost two orders of magnitude over the highest Reynolds number for turbulence measurements (Townes et al., 1972).

Results have led to a new set of scaling laws for turbulent pipe flow, showing that the almost universally accepted logarithmic behavior does not hold in the near-wall region. There, a power law holds instead, and a logarithmic behavior appears only at Reynolds numbers that are considerably greater than those commonly achieved in the laboratory. The scaling has been extended to boundary layer flows, and comparisons with existing data are very encouraging. The original mean flow data set is available here, and further details of the facility are given by Zagarola (1996). This work is ongoing, as are detailed studies of the turbulence behavior, which are focusing on the extension of these scaling laws to the turbulence behavior. This work is currently supported under ONR Grant N00014-97-I-0618 "Student Training Program in the Study of High Reynolds Number Turbulent Flows."

Relevent publications can be found in the papers section under superpipe