Search results
Results from the WOW.Com Content Network
In engineering, the Moody chart or Moody diagram (also Stanton diagram) is a graph in non-dimensional form that relates the Darcy–Weisbach friction factor f D, Reynolds number Re, and surface roughness for fully developed flow in a circular pipe. It can be used to predict pressure drop or flow rate down such a pipe.
where the pressure loss per unit length Δp / L (SI units: Pa/m) is a function of: ρ {\displaystyle \rho } , the density of the fluid (kg/m 3 ); D H {\displaystyle D_{H}} , the hydraulic diameter of the pipe (for a pipe of circular section, this equals D ; otherwise D H = 4A/P for a pipe of cross-sectional area A and perimeter P ) (m);
The friction loss is customarily given as pressure loss for a given duct length, Δp / L, in units of (US) inches of water for 100 feet or (SI) kg / m 2 / s 2. For specific choices of duct material, and assuming air at standard temperature and pressure (STP), standard charts can be used to calculate the expected friction loss.
English: A graphical depiction of the relationship between S = Δ p / L, the pressure loss per unit length of pipe, versus flow volume Q, for a range of choices for pipe diameter D, for air at standard temperature and pressure. Units are SI.
The viscous friction causes the flow properties to change along the duct. The frictional effect is modeled as a shear stress at the wall acting on the fluid with uniform properties over any cross section of the duct. For a flow with an upstream Mach number greater than 1.0 in a sufficiently long duct, deceleration occurs and the flow can become ...
For this model, the duct area remains constant and no mass is added within the duct. Therefore, unlike Fanno flow , the stagnation temperature is a variable. The heat addition causes a decrease in stagnation pressure , which is known as the Rayleigh effect and is critical in the design of combustion systems.
Pressure drop (often abbreviated as "dP" or "ΔP") [1] is defined as the difference in total pressure between two points of a fluid carrying network. A pressure drop occurs when frictional forces, caused by the resistance to flow, act on a fluid as it flows through a conduit (such as a channel, pipe , or tube ).
[1] [2] [3] A key question is the uniformity of the flow distribution and pressure drop. Fig. 1. Manifold arrangement for flow distribution. Traditionally, most of theoretical models are based on Bernoulli equation after taking the frictional losses into account using a control volume (Fig. 2).