High-Speed Dynamometers - Modern Water Brakes Offer New Potential for Testing Engines

New developments make water brakes suitable for an unlimited number of dynamometer applications. Performance, operation, and mechanical design of the multiple, perforated disc water brake is described. Principles of power absorption are discussed and various power absorption devices are compared.

Knowledge gained through 300,000 hr of testing gas turbine engines with water brakes makes it possible to produce compact, lightweight, dependable, low-cost water brakes. The deleterious effect of cavitation has been avoided. A water brake with a weight-to-absorbed power ratio of 0.025 lb/hp was developed.