Static Evaluation of a Circulation Control Centrifugal Fan.
Abstract
The static characteristics of a circulation control (CC) fan were determined to demonstrate the feasibility of the CC concept as a means of meeting the lift system requirements of a large, open ocean capable, surface effect ship (SES). These requirements being variable performance, at constant RPM, of sufficient range to provide for heave alleviation when operating at high speeds in advanced sea-states. The scope of the program included two solidity ratios within the model centrifugal impeller and, in effect, two volutes. The better performing combination of these variations was the low solidity (sigma = 0.65) impeller mated with a reduced internal volume volute. This fan demonstrated a flow rate increase of 100 percent over that achieved at the design point, through increasing the flow of control air, while maintaining a constant head rise. The peak efficiency of this combination was 83 percent. From this peak efficiency, achieved with a moderate amount of control air, the efficiency dropped to a low of 65 percent when operating with a maximum flow of control air. It is shown that the most likely demands of the heave alleviation system would allow for the fan to operate at the highest efficiency possible for the flow rate required. The high solidity (sigma = 1.3) impeller was found to produce an increase in flow rate of 50 percent over that achieved at the design point, through increased control air, and did not achieve as high an efficiency as that of the lower solidity configuration. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1977
- Accession Number
- ADA041463
Entities
People
- Robert E. Whitehead
- Roger J. Furey