virtaustilakäyrin

A virtaustilakäyrin, often translated as flow state curve or characteristic curve, is a graphical representation used in fluid dynamics and engineering to describe the performance of a centrifugal pump or fan. It illustrates the relationship between the flow rate (virtaama) and the total head (nostokorkeus) or pressure developed by the machine at a constant speed.

The curve typically starts at zero flow rate, where the pump or fan produces its maximum head, known as the shut-off head. As the flow rate increases, the head developed by the machine gradually decreases. This inverse relationship is a fundamental characteristic of centrifugal machinery due to factors like internal friction and recirculation losses.

The shape of the virtaustilakäyrin is crucial for selecting the appropriate pump or fan for a specific application. It helps engineers understand how the machine will perform under different operating conditions. When a pump is used in a system, its performance is determined by the intersection of its virtaustilakäyrin and the system curve, which represents the head losses in the piping system. This intersection point, known as the operating point, indicates the actual flow rate and head the pump will deliver.

The virtaustilakäyrin can also illustrate efficiency, power consumption, and cavitation characteristics at different flow rates. These additional curves, often plotted on the same graph, provide a comprehensive view of the machine's performance envelope. Factors such as impeller diameter, speed, and design variations can significantly alter the shape and position of the virtaustilakäyrin.