# Transferencia de momentum

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• Publicado : 30 de marzo de 2011

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Goal and Objectives Fundamental Theory Safety Rules Equipment Description Experimental Procedure Data Analysis Work Plan Schedule Lab Tour

Apply the laws ofconservation of mass and momentum and the mechanical energy balance for different geometries.

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Investigate the validity of the theoretical equations that describe the force emitted by a jet ofwater over targets of different geometries Determine the discharge coefficients and velocity coefficients of an orifice. Determine the relation between the water height and the flow of water enteringthe weir. Compare experimental values with theoretical values.

A fluid is a substance that deforms under an applied shear stress. Newtonian Non- newtonian
A fluid whose viscosity is variablebased on applied stress

A fluid that continues to flow regardless of the forces acting on it

Macroscopic Mass Balance

Rate of increase of mass

Rate of mass in At plane 1

Rate of massout At plane 2

S

Newton’s 2nd Law!

Mass flow rate (kg/s) , Velocity in plane 1, 2 (m/s) Momentum Change

Hemispherical Plate Flat Plate

Q

Q

Q ρ A

Volumetric Flow Rate Density ofthe fluid (kg/m^3) Cross-sectional Area of nozzle (m^2)

a) Flow Work b) Kinetic energy c) Potential Energy

a

b

c

Assumptions: 1. Fluid viscosity negligible 2. No friction losses inthe system 3. Steady-state 4. No mechanical work 5. No heat transfer

g Z P

Gravitational constant= 9.81 m^2/s Elevation (m) Pressure (N/m^2)

Assumptions: 1. Area of the tank is much greaterthan that of the orifice 2. No friction losses in the system 3. Steady-state 4. P1/ρ·g = P2/ρ·g 5. V1=0 and V2=V

If P=Patm

A0 = orifice area Avc = area vena contracta

•Discharge coefficient(CD) Fig. 15.5-5 BSL p. 471 Q = Avcvvc = (CcA0)(Cv (2gh)1/2) Q = A0CcCv (2gh)1/2 Q = A0CD (2gh)1/2 Q2 = 2(A0CD)2gh CD = CvCc

Combining Equations x=Vt

Vi  2 gh
Y=0.5 g t2

To find

x2 ...