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- 4.2 Turbine Casing -----------------------------------------------------------------------
- 4.3 Support Design -----------------------------------------------------------------------
- 4.3.1 Vertical Plate of the Support ------------------------------------------------------
- 4.3.2 Failure Theory ----------------------------------------------------------------------
- 4.3.3 Base of the Support ----------------------------------------------------------------
- 4.3.4 Failure Theory ----------------------------------------------------------------------
- 4.3.5 Bolts for Support -------------------------------------------------------------------
- 4.3.6 Weld for Supports------------------------------------------------------------------
- 4.4 Supporting Ring for Stator Blade ------------------------------------------------
- 4.4.1 Axial Force -------------------------------------------------------------------------
- 4.4.2 Screws for Supporting Ring ------------------------------------------------------
- 4.4.3 Tangential Force -------------------------------------------------------------------
- 4.5 Stator Disk ----------------------------------------------------------------------------
- 4.5.1 Design of Bolts ---------------------------------------------------------------------
- 4.5.2 Thickness of the Disk --------------------------------------------------------------
- 4.6 Outlet Disk ----------------------------------------------------------------------------
- 4.6.1 Design of Screws -------------------------------------------------------------------
- 4.6.2 Thickness of the Outlet Disk------------------------------------------------------
- 4.7 Inner Cone ----------------------------------------------------------------------------
- 4.8 Outer Cone----------------------------------------------------------------------------
- 4.9 Bolts for Inner and Outer Cone ---------------------------------------------------
- 4.9.1 Design of Bolts ---------------------------------------------------------------------
- 4.10 Outlet Duct----------------------------------------------------------------------------
- 4.11 Labyrinth Seal -----------------------------------------------------------------------
- 4.11.1 Bolt Design for Labyrinth Seal for Tensile Force ---------------------------
- Two and Three Dimensional Drawings -------------------------------------------------
- 5.1 Three Dimensional Models --------------------------------------------------------
- 5.1.1 Stator Blade -------------------------------------------------------------------------
- 5.1.2 Supporting Ring -------------------------------------------------------------------- x
- 5.1.3 Turbine Casing ---------------------------------------------------------------------
- 5.1.4 Supports of Turbine Casing -------------------------------------------------------
- 5.1.5 Stator Disk --------------------------------------------------------------------------
- 5.1.6 Outlet Disk --------------------------------------------------------------------------
- 5.1.7 Frame of Turbine -------------------------------------------------------------------
- 5.1.8 Labyrinth Seal ----------------------------------------------------------------------
- 5.1.9 Inner Cone and Outer Cone -------------------------------------------------------
- 5.1.10 Outlet Duct-----------------------------------------------------------------------
- 5.2 Two Dimensional Manufacturing Drawings ---------------------------------
- 5.2.1 Assembly Drawing -----------------------------------------------------------------
- 5.2.2 Outer Cone Drawing ---------------------------------------------------------------
- 5.2.3 Inner Cone Drawing ---------------------------------------------------------------
- 5.2.4 Turbine Inlet Casing Drawing ----------------------------------------------------
- 5.2.5 Turbine Outlet Casing Drawing --------------------------------------------------
- 5.2.6 Stator Disk Drawing ---------------------------------------------------------------
- 5.2.7 Labyrinth Seal Drawing -----------------------------------------------------------
- 5.2.8 Supporting Ring Drawing ---------------------------------------------------------
- 5.2.9 Outlet Disk Drawing ---------------------------------------------------------------
- 5.2.10 Frame of Turbine ----------------------------------------------------------------
- 5.2.11 Inlet Case Support Drawing ---------------------------------------------------
- 5.2.12 Outlet Case Support Drawing--------------------------------------------------
- 5.2.13 Stator Blade Drawing -----------------------------------------------------------
- 5.2.14 Outlet Duct Drawing ------------------------------------------------------------
- Manufacturing of Turbine ----------------------------------------------------------------
- 6.1 Pattern ---------------------------------------------------------------------------------
- 6.1.1 Pattern Material --------------------------------------------------------------------
- 6.1.2 Design Consideration in Patterns-------------------------------------------------
- 6.1.3 Design Allowances ----------------------------------------------------------------
- 6.1.4 Patterns of Turbine Parts ----------------------------------------------------------
- 6.2 Casting --------------------------------------------------------------------------------- xi
- 6.2.1 Sand Casting ------------------------------------------------------------------------
- 6.2.2 Casting of Turbine Parts-----------------------------------------------------------
- Results and Discussion --------------------------------------------------------------------------
- Appendix ------------------------------------------------------------------------------------------
- References ---------------------------------------------------------------------------------------
- Figure 1.1: Development of Engine Pressure Ration over the Year ------------------------- List of Figures
- Figure 1.2: Trend in Improvement in Firing Temperature ------------------------------------
- Figure 1.3: Overall Cycle Efficiency ------------------------------------------------------------
- Figure 2.1: Schematic Diagram for Air Craft Gas Turbine Engine --------------------------
- Figure 2.2: Schematic Diagram for Land Based Gas Turbine Engine -----------------------
- Figure 2.3: Brayton Cycle on T-S Diagram-----------------------------------------------------
- Figure 2.4: Irreversible Brayton Cycle on T-S Diagram --------------------------------------
- Figure 2.5: Stator and Rotor Blades of Axial Flow Turbine ---------------------------------
- Figure 2.6: (a) Pelton Wheel (Impulse Turbine) (b) Its Principle ---------------------------
- Figure 2.7: Pressure and Velocity Variation for Impulse and Reaction Turbine ----------
- Figure 3.1: Axial Flow Turbine Stage ----------------------------------------------------------
- Figure 3.2: Velocity Diagram -------------------------------------------------------------------
- Figure 3.3: Combined Velocity Diagram ------------------------------------------------------
- Figure 3.4: T-S Diagram for an Axial Flow Turbine Stage ----------------------------------
- Figure 3.5: Axial Flow Turbine Annulus ------------------------------------------------------
- Figure 3.6: Optimum Pitch to Chord Ratio ----------------------------------------------------
- Figure 3.7: Typical Labyrinth Seal -------------------------------------------------------------
- Figure 3.8: Flow in a Straight through Labyrinth Seal ---------------------------------------
- Figure 3.9: Nomenclature for Straight Seal ----------------------------------------------------
- Figure 3.10: Seal Loss Schematic ---------------------------------------------------------------
- Figure 4.1: Velocity Diagram -------------------------------------------------------------------
- Figure 4.2: Clearance between Stator and Rotor ----------------------------------------------
- Figure 4.3: Conical Pressure Vessel ------------------------------------------------------------
- Figure 4.4: Turbine Support ---------------------------------------------------------------------
- Figure 4.5: Cantilever Beam ---------------------------------------------------------------------
- Figure 4.6: Section Diagram of Cantilever Beam ---------------------------------------------
- Figure 4.7: Simply Supported Beam------------------------------------------------------------
- Figure 4.8: Free Body Diagram of Simply Supported Beam --------------------------------
- Figure 4.9: Section diagram of simply supported beam --------------------------------------
- Figure 4.10: Section diagram of simply supported beam ------------------------------------ xiii
- Figure 4.11: Supporting Ring -------------------------------------------------------------------
- Figure 4.12: Cantilever Beam -------------------------------------------------------------------
- Figure 4.13: Section Diagram of Cantilever Beam -------------------------------------------
- Figure 4.14: Diagram of Stator Disk -----------------------------------------------------------
- Figure 4.15: Semi Circular Disk ----------------------------------------------------------------
- Figure 4.16: Diagram of Outlet Disk -----------------------------------------------------------
- Figure 4.17: Semi Circular Outlet Disk --------------------------------------------------------
- Figure 4.18: Diagram of Inner Cone ------------------------------------------------------------
- Figure 4.19: Diagram of Outer Cone -----------------------------------------------------------
- Figure 4.20: Diagram of Circular Cone Showing Pitch Circle Diameter -------------------
- Figure 4.21: 3D And 2D Diagram of Outlet Duct --------------------------------------------
- Figure 4.22: Diagram of Labyrinth Seal -------------------------------------------------------
- Figure 4.23: Schematic Diagram of Labyrinth Seal ------------------------------------------
- Figure 4.24: Diagram of Labyrinth Seal Showing Pitch Circle Diameter ------------------
- Figure 5.1: Stator Blade of Single Stage -------------------------------------------------------
- Figure 5.2: Supporting of Stator Blades --------------------------------------------------------
- Figure 5.3: Supporting Ring and Stator Blades Assembly -----------------------------------
- Figure 5.4: Turbine Casing with Inlet and Outlet Casing ------------------------------------
- Figure 5.5: Support of the Turbine Casing -----------------------------------------------------
- Figure 5.6: Stator Disk ---------------------------------------------------------------------------
- Figure 5.7: Outlet Disk of Turbine--------------------------------------------------------------
- Figure 5.8: Frame of Turbine --------------------------------------------------------------------
- Figure 5.9: Labyrinth Seal -----------------------------------------------------------------------
- Figure 5.10: Inner Cone --------------------------------------------------------------------------
- Figure 5.11: Outer Cone -------------------------------------------------------------------------
- Figure 5.12: Outlet Duct -------------------------------------------------------------------------
- Figure 5.13: 3D Assembly Model --------------------------------------------------------------
- Figure 5.14: Outer Cone Drawing --------------------------------------------------------------
- Figure 5.15: Inner Cone Drawing ---------------------------------------------------------------
- Figure 5.16: Turbine Inlet Casing Drawing ----------------------------------------------------
- Figure 5.17: Turbine Outlet Casing Drawing -------------------------------------------------- xiv
- Figure 5.18: Stator Disk Drawing ---------------------------------------------------------------
- Figure 5.19: Labyrinth Seal Drawing-----------------------------------------------------------
- Figure 5.20: Supporting Ring Drawing --------------------------------------------------------
- Figure 5.21: Outlet Disk Drawing --------------------------------------------------------------
- Figure 5.22: Frame of Turbine ------------------------------------------------------------------
- Figure 5.23: Inlet Case Support -----------------------------------------------------------------
- Figure 5.24: Outlet Case Support Drawing ----------------------------------------------------
- Figure 5.25: Stator Blade Drawing -------------------------------------------------------------
- Figure 5.26: Outlet Duct Drawing --------------------------------------------------------------
- Figure 6.1: Electric Planner Machine-----------------------------------------------------------
- Figure 6.2: Band Saw Machine -----------------------------------------------------------------
- Figure 6.3: Support of Turbine ------------------------------------------------------------------
- Figure 6.4: Pattern of Turbine Inlet Casing ----------------------------------------------------
- Figure 6.5: Pattern of Turbine Outlet Casing --------------------------------------------------
- Figure 6.6: Stator Blade after Casing -----------------------------------------------------------
- Figure 6.7: Supporting Ring after Casting -----------------------------------------------------
- Figure 6.8: Supporting Ring after Machining Processes -------------------------------------
- Figure 6.9: Turbine Support after Casting -----------------------------------------------------
- Figure 6.10: Turbine Inlet Casing ---------------------------------------------------------------
- Figure 6.11: Turbine Outlet Casing -------------------------------------------------------------
- Figure 6.12: Labyrinth Seal----------------------------------------------------------------------
- Figure 6.13: Outer Cone -------------------------------------------------------------------------
- Figure 6.14: Inner Cone --------------------------------------------------------------------------
- Figure 6.15: Outlet Duct -------------------------------------------------------------------------
- Figure 6.16: Turbine Frame ---------------------------------------------------------------------
- Table 1-1: Chronology of Gas Turbine Development ----------------------------------------- List of Tables
- Table 1-2: Range of Different Parameters for Designing of Axial Flow Turbine ----------
- Table 1-3: Range of Different Parameters for Axial Flow Turbine Designing. ------------
- Table 3-1: Symbols of Different Variables ----------------------------------------------------
- Table 3-2: Ranges for Labyrinth Seal Parameters. --------------------------------------------
- Table 3-3: Clearance between Shaft and Labyrinth Seal -------------------------------------
- Table 4-1: Given Data for Designing of Axial Flow Turbine -------------------------------
- Table 4-2: Results of the Calculation -----------------------------------------------------------
- Table 4-3: Results of the Calculation for Screw ----------------------------------------------
- Table 4-4: Results of the Calculation of Bolts for Outer Cone ------------------------------
- Table 4-5: Results of the Calculation for Bolts of the Labyrinth Seal ----------------------
- Table 6-1: Parts of Turbine and Their Manufacturing Methods -----------------------------
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Abstract
The objective of thesis is manufacturing of laboratory scale Axial Flow Gas Turbine Casing system for single stage. Initially some basic theory as well as the history of the Axial Flow Gas Turbine will be discussed in this report. The report includes also calculations which are based on the constant root radius. This Axial Flow Gas Turbine is design for blade speed of 60 m/s, revolutions are 6000rmp (100rps), mass flow rate is 1 kg/s, inlet temperature is 900 K and for inlet pressure 2 bar. The design calculations include the mean, root and tip radii, the height, width of the stator blades and clearance between the stator and rotor, the shaft length (length of the casing) and the angle of divergence of the turbine casing. The report also consists the designing of supporting ring of stator blades, stator disk, supports of the turbines, for uniform guide of inlet air the cones being designed, the outlet disk and out let ducts. The report contains the 3D modeling through Pro-E wildfire 3.0 and the 2D manufacturing drawings. Some parts of the turbine will cast while some parts will manufacture through machining and cold working, so the reports contains which parts will be cast and which will be manufacture through other methods.
Table 1-1: Chronology of Gas Turbine Development Year Name Invention 130BC Hero of Alexandria Reaction Steam Turbine 1550 Leonardo da Vinci, Italy Smoke Mill 1629 Giovanni Branca, Italy Impulse Steam Turbine 1791 John Barber, England Steam Turbine and Gas Turbine 1831 William Avery, USA Steam Turbine 1850 Fernimough, England Gas Turbine 1884 Charles A. Parsons Reaction Steam Turbine & Gas Turbine 1888 Charles G.P. de Laval Impulse Steam Turbine Branca type 1895 George Westinghouse Steam Turbine Rights 1896 A.C. Rateau, France Multi Impulse Steam Turbine 1896 Charles Curtis Velocity Compound Steam Turbine/Gas Turbine 1895 Dr. Zoelly, Switzerland Multi Impulse Steam Turbine 1900 F. Stolze, Germany Axial Compressor & Turbine Gas Turbine 1902 Stanford A. Moss, USA Turbo-Charger/Gas Turbine 1908 Karavodine Gas Turbine with deLaval Steam Turbine 1908 Holzwarth Gas Turbine with Curtis + Rateau Com pressor - 1930 Frank Whittle, England Aero Gas Turbine (Jet Engine) 1938 Brown Boveri—, Switzerland 1st Commercial Axial Compressor & Turbine
The Industrial Gas Turbine has always emphasized long life and this conservative approach has resulted in the Industrial Gas Turbine in many aspects giving up high performance for rugged operation. The Insustrial Gas Turbine has been conservative in the pressur ratio and the firing temperatures. This has all changed in the last 10 years;
spurred on by the introduction of the “Aero-Derivative Gas Turbine” the industrial gas turbine has dramatically improved its performance in all operationas aspects. This has resulted in dramatically reducing the performance gap between these two types of gas turbines. The gas turbine to date in the combined cycle mode is fast replacing the steam turbine as the base load provider of dlectrical power throughout the world. Figures 1.1 and 1.2 [1]. show the growth of the pressure ratio and firing temperature. The growth of both the pressure ratio and firing temperature parallel each other, as both growths are necessary to achieving the optimum thermal efficiency.
Figure 1.1: Development of Engine Pressure Ration over the Year
Figure 1.2: Trend in Improvement in Firing Temperature
The increase in pressure ratio increases the gas turbine thermal efficiency when accompanied with the increase in turbine firing temperature. Figure 1.3 [1] show the
1.4 Problem Definition
More than one design parameters are to be addressed simultaneously for an efficient design under a given condition. These parameters include blade loading coefficient, flow coefficient, mass flow rate, Hub to tip ratio, tip speed, height of the blade, rotational speed, pressure ratio, degree of reaction, isentropic efficiency, blade and air inlet and outlet angles and power output. The number of stages is only one. A design based on constant root radius will be good for manufacturing ease. Similarly a repetition stage will also be beneficial for an ease in blades manufacturing because the blade angles will be same for each row of blades. The ranges of parameters to be used in the designing are given below in table 1-2.
Table 1-2: Range of Different Parameters for Designing of Axial Flow Turbine
Parameter Value range
Blade Loading Coefficient ' ' 3-
Swirl Angle ' 3 ' 0°-20°
Flow Coefficient ' ' 0.8-
Degree of Reaction ' ' 50%
Nozzle Exit Angle ' 2 ' >60°
Height to chord ratio hc 3-
Staying within the above main constraints, the design of a small size axial flow gas turbine along with the manufacturing drawings will be the main task.
Table 1-3: Range of Different Parameters for Axial Flow Turbine Designing.
Parameter Value range
Space to blade width ratio 0.25-0.
Lift Coefficient CL 0.9-1.
Number of blades ' n ' 11-
opening to pith ratio os 0-
Surface curvature downstream of throat (^) es 0.25-0. Leading edge radius 0.05s-0.1s
Trailing edge thickness ' ste ' 0.015c-0.05c
Stagger angle ' ' In range of 30°, 45°, 60°
Hub to tip ratios r t
r (^) r
Angle of divergence 25°
2.1 The Brayton Cycle
Theoretical cycle on which gas turbine power plants work is the Brayton cycle. Brayton cycle is based on ideal processes throughout the gas turbines. An ideal process is one which is adiabatic (no heat gain or loss to or from the system). Also the ideal processes are reversible i.e. the fluid passes through a continuous series of equilibrium points. The state point can be located on Ts diagram and both the fluid and its surrounding come back to their original state. A reversible adiabatic process is thus an ideal process also known as isentropic process [7]. Ideal Brayton cycle is shown on Ts diagram in figure 2-3 [6] and consists of the following processes [8].
- Process 1-2 Isentropic compression in the compressor
- Process 2-3 Constant pressure heat addition in combustion chamber
- Process 3-4 Isentropic expansion inside the turbine
- Process 4-1 Constant pressure heat rejection
Figure 2.3: Brayton Cycle on T-S Diagram
Actual processes in the turbines or compressors are not completely adiabatic because there are no perfect insulations so some amount of heat is exchanged by the system with the surroundings. In practice all processes are irreversible. This irreversibility is due to friction between moving parts, large temperature and large pressure differences between
the system and surroundings and there is always an increase in entropy. Actual processes in gas turbine are shown in figure 2-4 [6] and consist of the following processes [8].
- Process 1-2 Adiabatic process compression
- Process 2-3 Isobaric process heat Addition
- Process 3-4 Adiabatic process expansion
- Process 4-1 Isobaric process heat Rejection
Figure 2.4: Irreversible Brayton Cycle on T-S Diagram
2.2 Turbine Classification
Mainly the rotodynamic turbine may be classified into two ways: firstly by the direction of flow of the fluid relative to the rotor; secondly by the way in which the rate of change of angular momentum is achieved. The flow of fluid can be either in a direction parallel to the axis of rotor, in a radial direction or in a mixed mode [7]. The main classification according to the type of flow is given below:
- Axial flow turbine
- Radial flow turbine
- Mixed flow turbine However the thesis work is concerned with the axial flow gas turbine.
2.4 Types of Axial Flow Turbine
On the basis of energy available at the rotor inlet, there are two types of axial flow turbine: Impulse turbine Reaction turbine
2.4.1 Impulse Turbine
The impulse turbine has its entire enthalpy drop in the Nozzle; therefore it has a high velocity entering the rotor. The energy available at the entrance to the rotor of the impulse turbine is entirely kinetic energy. Figure 2-7 shows the velocity and pressure variation of fluid in the nozzle and rotor passages. In the impulse type turbine there is no net change in pressure between rotor inlet and rotor exit. Therefore, the blades relative discharge velocity will be the same as its relative inlet velocity. The nozzle guide vanes are shaped to form passages, which increase the velocity and reduce the pressure of the escaping gases. Figure 2-6 (b) shows the runner of the pelton wheel which is an impulse turbine. It alters the direction of the impinging fluid by 180°.
Figure 2.6: (a) Pelton Wheel (Impulse Turbine) (b) Its Principle
2.4.2 Reaction Turbine
The fluid entering to the rotor blades of the reaction turbine, posses both kinetic as well as pressure energy. In the reaction turbine the nozzle guide vanes only alter the direction of flow for the proper entry to the rotor. The reaction turbine divides the enthalpy drop in
the nozzle and the rotor passages. Each stage of reaction turbine consists of the fixed row of blades over the whole circumferential annuluses which are called stator blades, nozzle guide vanes or stator as shown in figure 2.5. Admission in the reaction turbine takes place in the complete annulus. The fixed blades are of nozzle shape and there is comparatively small drop in pressure accompanied by an increase in velocity. The fluid then passes over the moving blades and as in the pure impulse turbine a force is exerted by the fluid on the blades. There is further drop in pressure as the fluid passes through the moving blades. Since the moving blades are also of nozzle shape and therefore there is an increase in the fluid velocity in the rotor. The decrease in pressure and increase in velocity of the gas is accomplished by the convergent shape of the passage between the rotor blades. Figure 2-7 shows the basic difference in the velocity and pressure variation inside the impulse and reaction turbines.
Figure 2.7: Pressure and Velocity Variation for Impulse and Reaction Turbine
Most of the axial flow turbines consist of more than one stage. The impulse stages produce about twice the output of a comparable 50% reaction stage, while the efficiency of an impulse stage is less than that of 50% reaction stage.
