# Static Efficiency

on . Posted in Classical Mechanics

Static efficiency, abbreviated as SE, a dimensionless number, is a measure of an air mover's efficiency based on its air horsepower in terms of flow and static pressure vs. required shaft input power.  Static efficiency is a term commonly used in the context of fluid dynamics and turbomachinery, particularly for pumps and turbines.  It refers to the efficiency of a device when it is operating under steady state or static conditions.

In turbomachinery, such as pumps and turbines, energy is transferred from a fluid to mechanical work or vice versa.  The efficiency of these devices is a measure of how effectively they can convert energy without losses.  Static efficiency specifically focuses on the efficiency when the device is operating at a specific point or condition without accounting for transient or dynamic effects.

Static efficiency is typically expressed as a percentage and is calculated by comparing the actual power or work output to the ideal or theoretical power or work output.  The actual power output refers to the actual work or power delivered by the device under operating conditions, taking into account losses due to factors such as friction, mechanical inefficiencies, and fluid flow losses.  The ideal power output represents the theoretical maximum work or power that could be obtained if there were no losses or inefficiencies.

Static efficiency is an important parameter for assessing the performance of turbomachinery and evaluating the energy conversion efficiency.  It helps engineers and designers optimize the design and operation of pumps, turbines, and other fluid handling devices to achieve higher efficiency and minimize energy losses.

## Static Efficiency Formula

$$\large{ SE = \frac{ HP_o }{ HP_i } }$$
Symbol English Metric
$$\large{ SE }$$ = static efficiency $$\large{dimensionless}$$
$$\large{ HP_i }$$ = horsepower input $$\large{\frac{ft-lbf}{sec}}$$ $$\large{\frac{Btu}{s}}$$
$$\large{ HP_o }$$ = static horsepower output $$\large{\frac{ft-lbf}{sec}}$$ $$\large{\frac{Btu}{s}}$$

Tags: Efficiency