OPERATIONAL CAPABILITIES. Off Frequency Operation The primary operating consideration of an LP turbine under load at either greater or less than normal system frequency is the protection of the tuned blading so that harmonic resonance does not occur. In the design verification process, great care is taken to properly tune the tapered and twisted blades that constitute the last LP stages. The result of improved manufacturing techniques combined with a more rugged geometry is an improved off frequency capability. HIGH BACK PRESSURE OPERATION -------------------------------------------------------------------------------- Proprietary Information Page 12 AES IRONWOOD CONTRACT FINAL ISSUE - OCTOBER 30, 1998 -------------------------------------------------------------------------------- Westinghouse performed a detailed test in a dynamic blowdown wind tunnel which was designed to specifically investigate such instabilities at low volumetric flow. An original design blade which did demonstrate this flutter condition, as evidenced from the field telemetry testing, was thoroughly tested; verifying that the blade tip region could experience self-excited vibrations or blade flutter. Most important, these tests further verified that orientation of the blade tip is the principal parameter that controls the susceptibility for flutter; and that minimizing the incidence angle minimizes the likelihood of flutter and the high stresses associated with it. All Westinghouse last row blades are designed to allow maximum backpressure operation while minimizing susceptibility to flutter. As a result of this effort, the LP turbine is capable of continuous high load operation with a maximum backpressure of 20.3 cm (8.0") HgA.
Appears in 3 contracts
Sources: Engineering, Procurement and Construction Services Agreement (Aes Ironwood LLC), Engineering, Procurement and Construction Services Agreement (Aes Ironwood LLC), Engineering, Procurement and Construction Services Agreement (Aes Ironwood LLC)