A single-stage subsonic compressor was examined with respect to compressor instabilities. During the inception of rotating stall, the transients of the pressure rise and mass flow were measured as well as their hysteresis. The development of the stall cell and the characteristics of the unstable operating range were determined.Several measurement techniques and data analysis methods for the real-time detection of unstable compressor operation and aspects of their implementation on a digital signal processor are discussed.The results of the work are meant to serve as a basis for the design of an active stall avoidance system.

Includes any simple suction head used on a hose from a vacuum truck or a portable pump. To be considered in this category the skimming head must only be a suction device and not include any oil/water separation device such as a weir. Typical skimming heads are small and maneuverable, allowing their use in confined spaces such as among dock pilings. They can be operated from small boats, or dock side with vacuum trucks. Oil/water separators are recommended to deal with the large volumes of water that may be recovered along with the oil.

Zero relative velocity (ZRV) Skimmers are rope mop devices used in catamaran hull vessels. A series of separate ropes (generally four to six) are arranged between the hulls. They are allowed to hang loosely on the water surface and are rotated aft at a velocity close to the forward speed of the vessel. Velocity of the ropes relative to the oil on the water is close to zero.