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Centrifugal Compressor Description Slides
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UNIVERSITY OF WEST BOHEMIA
FACULTY OF MECHANICAL ENGINEERING
DEPARTMENT OF POWER SYSTEM ENGINEERING
Inovace předmětu „TEORIE PROUDOVÝCH STROJŮ “ v rámci projektu CZ.1.07/2.2.00/15.0006
JET ENGINESJET ENGINES
Centrifugal flow compressorsCentrifugal flow compressors
INTRODUCTION
PURPOSE OF COMPRESSORS● Compressor is a device which provide a compression
of air and its transport to combustion chamber in a required amount to ensure continuous process of combustion.
● Compression in centrifugal flow compressor is achieved by centrifugal velocities
● The air in outlet from blade canal is upright to axis of rotation
● Velocity of outlet air depends by diameter of blades and rotor's RPM
INTRODUCTION
Requirements ● Continual supply of required amount of air to
combustion chamber● High values pressure ratio● Stable work in each conditions where engine works● High values of efficiency● Low price● Minimal weight and dimensions● Simple construction and maintenance
INTRODUCTION
Advanteges● Higher pressure ratio in one stage (π=10)● Low length in axial direction● Good efficiency
Disadvatages● High frontal drag● Its necessary to use on outlet a diffuser and
manifold
COMPRESSOR TYPES
TYPES DEVIDED BY DIRECTION OF INLET● Axial inlet● Radial inlet● Diagonal inlet● Single-entry inlet● Dual-entry inlet
TYPES DEVIDED BY NUMBER OF STAGES● Single stage compressors● Dual stage compressors
EXAMPLES
Fig. 2 Centrifugal flow compressor with single axial inlet
EXAMPLES
Fig. 3 Centrifugal flow compressor with dual-entry radial inlet
EXAMPLES
Fig. 4 Centrifugal compressor with single diagonal inlet
COMPRESSOR TYPES
TYPES DEVIDED BY TYPE OF IMPELLER● Single-entry impeller● Dual-entry impeller● Impeller with straight blades● Impeller with curved blades forward● Impeller with curved blades backward● Closed impeller case● Semi-open impeller case● Open impeller case
EXAMPLES
Fig. 5 Single and dual entry impeller
EXAMPLES
Fig. 6 Impellers shape and cases
Straight Curved forward Curved backward
Opened Semi-opened Closed
COMPRESSOR TYPES
TYPES DEVIDED BY NUMBER OF STAGES● Single stage compressors● Dual stage compressors
TYPES DEVIDED BY ARRANGEMENT OF SPOOL
● Bladed diffuser● Non-bladed diffuser
EXAMPLE
Fig. Dual stage centrifugal flow compressor
EXAMPLES
Fig. Various types of dual stage centrifugal compressors
MAIN PARTS
Fig. Main parts of centrifugal flow compressor
MAIN PARTS
Fig. Impeller
MAIN PARTS
Fig. Particle move through the non-blade diffuser
MAIN PARTS
Fig. Particle move through the blade diffuser
MAIN PARTS
Fig. Bladed diffuser
MAIN PARTS
Fig. Output manifold and its loads
MAIN LAYERS
Fig. Layers through the compressor
PARAMETERS TROUGH THE COMPRESSOR
Fig. 7 Ideal and real process of compression in T-S diagram
PARAMETERS THROUGH THE COMPRESSOR
Fig. Evolution of parameters through the compressor
PARAMETERS THROUGH THE COMPRESSOR
Fig. Evolution of velocity parameters through the impeller
BASIC PARAMETERS
ABSOLUTE PRESSURE RATIO
Is non-dimensioned parameter. It is a ratio of outlet an inlet absolute pressure in compressor.
p1a
– absolute pressure value before compressor [Pa]
p5a
– absolute pressure value behind compressor [Pa]
Ca=p5a
p1a
BASIC PARAMETERS
ABSOLUTE COMPRESSOR EFFICIENCY
Is a ratio of adiabatic work and effective work of compression in compressor.
Ca=W ad ,Ca
W e ,Ca
=c p.T 5ad ,a−T 1a
c p. T 5a−T 1a [1]≈0.78−0.82
BASIC PARAMETERS
ηCa
– absolute compressor efficiency[1]
Wad,Ca
– absolute adiabatic compress work [J.kg-1]
We,Ca
– absolute polytropic compress work [J.kg-1]
cp – heat capacity at constant pressure [J.kg-1.K-1]
T5ad,a
– absolute adiabatic gas temperature on the end of compression [K]
T5a
– absolute polytropic gas temperature on the end of compression [K]
T1a
– absolute temperature on the beginning of compression [K]
BASIC PARAMETERS
AIR FLOW RATE
Define mass flow rate of air by one second, which flows trough the compressor.
Q a=ϱ . c1. A1[ kg.s−1]
BASIC PARAMETERS
Qa – Air flow rate through the compressor [kg.s -1]
Qa≈ 25 kg.s-1 (single-entry impeller)
Qa≈ 50 kg.s-1 (single-entry impeller)
ρ – Density [kg.m-3]
c1 – Absolute velocity of the air in the inlet [m.s -1]
A1 – Inlet flow area [m2]
REFERENCES
● Otis, Vosbury: Aircraft gas turbine powerplants – Jeppesen: 2002
● Rolls royce – The jet engine, 1996● Hanus D., Maršálek J, : Studijní modul 15,
Turbínový motor, CERM, s.r.o. Brno 2004● Kadrnožka J.: Tepelné turbíny a
turbokompresory, CERM, s.r.o. Brno 2004
DISCUSSION...
...QUESTIONS