Lecture 20 Intro to Turbomachines
Turbomachines are mechanical devices that either extract energy from a fluid or
add energy to a fluid.
Classifications of Turbomachines
Axial Flow
Radial Flow
Mixed F
One Dimensional Compressible Flow
Conditions for One-Dimensional Compressible Flow
Stagnation Conditions for Incompressible Flow
Stagnation Conditions for Compressible Isentropic Flow
Bring fluid with
Blasius Exact Solution for Flat Plate
Goal: Find Boundary Layer Thickness at any distance along a flat plate
Analysis
Apply Navier-Stokes in x-direction and Momentum Equation to the
boundary layer.
Tr
Fluid Kinematics
Particle Acceleration
a
a
V dx
V dy
V dz
x dt
y dt
z dt
V
V
V
V
u
v
w
x
y
z
t
V
t
Scalar Form
ax
ay
az
u
u
u
v
w
x
y
z
v
v
v
u
v
w
x
y
z
w
w
w
u
v
w
x
y
z
u
t
v
t
w
t
u
Substantial De
Review of Basic Concepts
Define a Fluid
Methods of Description - Eulerian and LaGrangian
Continuum Assumption
Property Fields
Streamlines
dy
dx
u
Pathlines
v
Classification of Fluid Mechanics
v
u
dx
d
External Flow and the Boundary Layer Concept
Introduction to External Flow
Lift and Drag
Lift
Drag
External Flow Characteristics
The Boundary Layer
Viscous and Inertia Forces in the Boundary Layer
Sep
Boundary Layer Friction and Pressure Drag
Pressure Gradients
Effect of Pressure Gradient on Inviscid Flow:
Adverse pressure gradient Pressure increases in direction of flow, causing
decrease in free s
Compressible Flow
Thermodynamics Review of Ideal Gases
Ideal Gas Law
Internal Energy Relation
Enthalpy
Additional Relations
Entropy Relations
Isentropic Flow
Mach Number and Speed of Sound
where c = s
Normal Shocks
Apply the Energy Equation and Continuity to the Control Volume
T-s Diagram
How will the properties change across the shock wave?
Property Ratio Equations
Example
In a c-d nozzle, air flo