UNIVERSITY OF WEST BOHEMIA FACULTY OF MECHANICAL ENGINEERING DEPARTMENT OF POWER SYSTEM ENGINEERING Ratkovská Katarína
Feb 23, 2016
UNIVERSITY OF WEST BOHEMIAFACULTY OF MECHANICAL ENGINEERING
DEPARTMENT OF POWER SYSTEM ENGINEERING
Ratkovská Katarína
JET ENGINES
HISTORY• 17.12.1903 Orvill Wright and Wilburom Wright
- first controlled flight
• 1935 Frank Whitley- patented principle of jet engines
• 27.8.1939 Hans von Ohain- HeS – 3B jet engine
W - 1
He - 178
TYPICAL ENGINE CUTS
0 – 1 engine intake1 – 2 compressor2 – 3 main combustion chamber3 – 4 gas turbine4 – 5 exhaust system
VK 1 engine with radial
compressor
RD 33
MiG-29
BASIC PARAMETERS
• Engine thrust [N]- It's more important parameter, which is
characterized a jet engines with direct reaction
[N ]Where:- mass flow rate []- – output gas velocity []- – air speed []
• Engine thrust [N]
mass flow rate - gas [] mass flow rate - air [] – output gas velocity [] – air speed []
• Engine performance P[W] turbo-prop engines
- – propeller thrust [N]- – air speed- – propeller efficiency [1]
Turboprop engine TP 100
TS - 21
- Turboshaft engine with free gas turbine.- It is starter of R-27F2M-300 engines.
Mig 23 - FLOGGER
• Air mass flow rate[] - Quantity of air that flows through the engine
in second.
=
• m – air mass [kg]• t – time [s]
• Specific engine thrust Fm []
• Hour fuel consumption [kg.]
- Fuel flow rate.
• Total compressor pressure ratio - Define ratio between total pressure on compressor
output to total pressure on compressor input.
– total air pressure on compressor input [Pa] – total air pressure on compressor output [Pa]
COMPRESSOR TYPESCentrifugal flow compressors
AXIAL FLOW COMPRESSORS
• Total absolute temperature before turbine stage [K]
- is the temperature value on combustion chamber output before turbine stage.
T3T = t3T+273,15 [K]
• Total absolute temperature behind turbine stage [K]
T4T = t4T+273,15 [K]
THERMAL CYCLE
• Jet engines are reactive engines witch works with atmospheric air. Purpose of air in this case is:
- Basic component of working media in thermodynamic cycle- Oxygen included in air is used during chemical reaction of burning- Accelerated air (in case of engines with direct reaction) create trust
SfJE - Ideal thermal cycle
SfJE with afterburner – ideal thermal cycle
WORK OF IDEAL THERMAL CYCLE
• In p-V diagram
• In T-s diagram
1,,. . kgJWWW adkomadexid
121. . kgJqqWid
WORK OF IDEAL THERMAL CYCLE
Ideal expansion work of gas:
1013
3
5353,
.11...11..
1..
kgJe
TcTc
TTTcTTcW
pp
ppadex
EFFICIENCY OF IDEAL CYCLE - SfTJE
• Quality of transformation of input heat “” to work “” is described by thermodynamic efficiency “”
111111..
1.1..
10
0
1
ee
eeTce
eTc
qW
p
pi
t
DEPENDENCE OF “” BY “”
WORK OF IDEAL THERMAL CYCLE - SfTJE
0
3
.
1
. TTe
opt
opt
0dedWi
1.2
0
31.2.
TT
opt
CONCLUSION
• Work of ideal cycle in thermodynamics is characterized by efficiency .
• Thermal efficiency of cycle depend by pressure ratio π and temperature ration /
DISCUSSION
QUESTIONS