XI - 1 XI. Turbomachinery This chapter considers the theory and performance characteristics of the mechanical devices associated with the fluid circulation. General Classification: Turbomachine - A device which adds or extracts energy from a fluid. Adds energy: Pump Extracts energy: Turbine In this context, a pump is a generic classification that includes any device that adds energy to a fluid, e.g. fans, blowers, compressors. We can classify pumps by operating concept: 1. Positive displacement 2. Dynamic (momentum change) General Performance Characteristics Positive Displacement Pumps1. Delivers pulsating or periodic flow (cavity opens, fluid enters, cavity closes, decreasing volume forces fluid out exit opening. 2. Not sensitive to wide viscosity changes. 3. Delivers a moderate flow rate. 4. Produces a high pressure rise. 5. Small range of flow rate operation (fixed pump speed). Dynamic Pumps1. Typically higher flow rates than PD’s. 2. Comparatively steady discharge. 3. Moderate to low pressure rise. 4. Large range of flow rate operation. 5. Very sensitive to fluid viscosity.
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