Propeller Design (Detail Stage)
To this point we have developed the K T vs J2 (J4 ) design approach. Most references present the series data in
alternative format. One version is curves of constant efficiency and 1/J on a scale of P/D vs B P1 or P/D vs
Kq

section 3.4 Resistance & Propulsion
source: Woud
Chapter 3
3.4.1 Hull Resistance
2
R := c1 v s
physics
PE := R v s
R
PE = effective_power
(3.1)
(3.2)
defined
(3.3)
3
PE c1 v s
substitution
( )
c1 := y c0 v s
(3.4)
physics
y = f( fouling , displacement_

Combustion
define some units
3
combustion of dodecane a parafin of type CnH2n
(represents diesel fuel) in stochiometric proportions:
kN := 10 N
6
MPa := 10 Pa
C12H26 + x O2 = y H2O + z CO2 + heat
3
kPa := 10 Pa
3
kJ := 10 J
3
kmol := 10 molebar := 0.1MPa

Availability
From chapter 8 VW&S
control volume in uniform state, uniform flow process USUF, irreversible Q c.v. and Wc.v.
what if process were reversible, how much work would have been done if the process had been reversible
<= reversible heat
engine
Wre

these notes are landscape
as plots are usually shown in
that mode
Using KT and KQ for design
we have seen in general the development of the Wageningen B series. The performance curves are available either in chart form or can be generated from
polynomials

First Law
first law: during any cycle a system undergoes, the cyclic integral of the heat is proportional to the cyclic
integral of the work
pg 83 van Wylen & Sonntag Fundamentals of Classical Thermodynamics 3rd Edition SI Version
1 dQ = 1 dW
first law f

Polytropic Efficiency
kJ := 1000J
consider a two stage compressor with a stage efficiency = 0.9
p 1 := 1bar
p 2 := 5bar
kJ
s1 := 1
kg K
p 3 := 20bar
stage := 0.9
calculations
the states resulting are plotted .
Temperature
800
600
400
200
0.95
1
1.05
1.1

Second Law
Kelvin-Planck: It is impossible to construct a device that will operate in a cycle and produce no effect other than the
raising of a weight and the exchange of heat with a single reservoir.
Clausius: It is impossible to construct a device that

Waterjet
VA
velocity inlet
w
Vs
Vj
wake fraction
ship velocity
nozzle (outlet) velocity
h
Vj
VA := Vs(1 w)
(
)
T = m_dot VJ VA
d
m_dot = mass_flow_rate
VA
p local = p atmos + g d
at inlet centerline .
1
1
2
2
p oin = p local + VA = p atmos + gd + VA
2
2
a

Properties of Water
a k a Thermodynamic Properties of Working Fluids with Phase change
discussion of water properties, T s diagram, stauration, phase change, h - s diagram critical pressure
~ figure 3.3 VW & S
T temperature deg C
600
400
200
0
0
2
4
6
s e

Rankine cycle
rev 2 added s = constant interpolation
area to determine state 2 enthalpy and
corrected T2 calc
this file calculates reversible Rankine cycle with following parameters:
condenser 40 deg C
steam pressure 30 bars (3 MPa)
superheat 460 deg_C
3

Propeller Testing
Screw propeller replaced paddle wheel ~1845 in Great Britain (vessel) - Brunel
In test;
independent variables are
velocity of advance
VA
shaft rotation speed
n (rev/sec), N (rev/min)
dependent variables are:
torque
Q
thrust
T
i.e. we bui

Basic Practical diesel cycle
define some units
3
kN := 10 N
The textbook Diesel cycle is represented by all heat addition at constant
pressure. The Otto cycle which is implemented by the spark ignition internal
combustion engine adds all heat at constant

Summary of Thermo
First Law
1 dQ = 1 dW
first law for cycle
first law for system
change of state
Q1_2
Q1_2 = E2 E1 + W1_2
E1
(5.2)
is the heat transferred TO system
E2
are intial and final values of
energy of system and .
W1_2
(5.5)
is work done BY the s