[L1] 1 Throttling [L2] 1) Definition [L4] - A device or process where fluid in a pipe passes through a suddenly narrowed passage (nozzle, orifice), lowering pressure and temperature without doing external work. [L4] - Morphologically, the pipe line suddenly narrows, which is called a throttling device, and this pressure drop/temperature drop phenomenon is called throttling (phenomenon). [L2] 2) Features [L4] - If the throttling phenomenon occurs in an adiabatic state, pressure and temperature can be lowered. (Adiabatic Expansion) [L1] 2 Nozzle [L2] 1) Definition [L4] - A device that creates a high-speed fluid jet. [L4] - A device that decreases pressure energy and increases kinetic energy. [L4] - A device utilizing the principle that pressure energy converts to velocity energy when high-pressure liquid is ejected through a small cross-sectional area. [L2] 2) Features [L4] - Used in automotive carburetors, sprayers, and kerosene outlets of pressurized kerosene stoves. [L4] - Used in water wheels and steam turbines to eject water or steam from nozzles to rotate impellers at high speed, converting velocity energy into mechanical energy. [L4] - A nozzle with a tapered end is called a convergent nozzle, and one that narrows and then widens at the end is called a divergent (expanding) nozzle or De Laval nozzle. [L4] - Supersonic flow can be obtained by narrowing and then widening the flow area. [L2] 3) Flow inside Nozzle [L4] - Exit Velocity : V=(2(h1-h2)^0.5 [L4] - Sonic Velocity : C=(kRT)^0.5 [L5] * k : J/kg, R : J/kgK [L4] - Critical Pressure [L5] * Pc = P1(1/(K+1))^(k/(k-1)) Source : Naver Encyclopedia [L1] 3 Orifice [L2] 1) Definition [L4] - A hole that ejects fluid, referring to a throttling passage (a structure connecting passages by drilling a hole in a plate). [L2] 2) Features [L4] - Mainly used to measure flow rate. [L4] - One of the throttle mechanisms installed in the middle of a pipeline, serving as a primary conversion element for flow-differential pressure. [L4] - A throttle form consisting of a thin plate with a hole smaller than the cross-sectional area of the pipe installed in the middle of the pipeline, with sharp edges on the inflow side. [L4] - Utilizes the principle that the pressure difference changes according to the flow rate when fluid flows through it. [L4] - In addition to concentric orifices where the hole is concentric, there are eccentric orifices and segmental orifices. [L1] 4 Diffuser [L2] 1) Definition [L4] - A device that increases the static pressure of a fluid by decreasing its velocity. [L4] - Refers to an expanding pipe used to smoothly reduce fluid velocity and increase static pressure. [L2] 2) Features [L4] - Assuming the relationship between inlet 1 and outlet 2 of the expanding pipe as shown below is independent of height position and viscosity loss is negligible, the following relationship holds. Source : Naver Source : Naver [L4] - Efficiency is maximized when the divergence angle is 4~5° (Loss is minimal at this angle). [L4] - Laval nozzles with a narrow throat (slot) are widely used to recover static pressure by slowing down supersonic compressible fluids.