Steam Engine Project

1
Steam Engine Project

• Department Discussions / Brainstorming Of The
  Steam Engine Development Program
• Using The Interface Check List To Start The
  Abstraction Phase Of Design
• Kinematics Analysis Of Piston Engines
• Thermodynamics Of Piston Expander Engines

2
Development Using The Interface Check List

• Basic Sketch
• Develop Math Model
• Describe System Physics
• Preliminary Structural Requirements
• Preliminary Design Intent
• Structural Analysis
• Identify Interfaces

• Allocate Tolerances
• Assembly Process
• Component Selection
• Modeling Flow Chart / Model Parts
• Final Tolerance Check At Each Interface

3
Design Intent

• What is Design intent for a crank and slider?
• Turn translation energy exerted by steam on
  piston into rotation energy / motion on the
  crankshaft.

4
Basic Crank And Slider DesignSide View
Bore
Stroke
½ Stroke
5
Basic Crank And Slider DesignTop View
6
Basic Sketch Of Motor

• No porting
• No mounting harware

Rear bearing
Forward bearing
Connecting rod
Crank shaft
Crank support
Cylinder Block
Cylinder head
Rear crank case
Side View
Piston pin
7
Basic Sketch Of Motor

• How Do We Describe The Physics Of Operation?
• How Much Power Will It Make With RDs Steam
  Source?

Inlet Port Exhaust Port
Side View
8
Requirements For Engines

• The Engines Must Use Standard Bearings
• McMaster Car
• Piston Clearance Volume Between 2-5 Of Max
  Cylinder Volume
• Piston Area x Stroke Max Cylinder Volume
• Clearance Volume .02 x Max Cylinder Volume
• Other Tolerances To Be Discussed In Department
  Meetings

9
Basic Piston Expander DesignRear View
Bore
½ Stroke
Basic Kinematics Linkage
10
Piston Engine Kinematics
11
Power TransmissionFBD Of Piston
12
Shaft Torque From Piston
13
How Do We Evaluate Cylinder Pressure To Obtain
Power?

• Thermodynamics Portion Of The Analysis
• Need To Make Some Basic Simplifying Assumptions
• Consider The Cylinder The Control Volume
• First Pass Assume No Heat Transfer
• Adiabatic No Heat Transfer
• Reversible Process - Isentropic
• Simple Valve Operation

14
Thermodynamic Analysis

• Assuming A Closed Adiabatic System
• Ideal Gas Behavior
• Simple Valve Operation

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Engine ThermodynamicsWhats Happening In The
Cylinder?
1 Intake Opens 2 Top Dead Center 3 Intake
Closes 3-4 Adiabatic Expansion 4 Exhaust Opens 5
Bottom Dead Center 6 Exhaust Closes
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Next Steps

• Utilize The Kinematics and Thermodynamics To
  Complete Simulation Provided On Web Site
• Simulation Will Evaluate
• Output Torque
• Component Loading
• Cylinder Pressures and Temperatures
• Utilize Component Loading In Stress Analysis Of
  Various Parts

17
Simulation Inputs

• The RD Department Has Refined The Steam
  Generator To Produce 500 psi Steam At 400 ºF.
• Utilize These Inputs For Your Engine Performance
  Predictions
• Vary Valve Port Timing To Try To Optimize Output
  Power / Efficiency.

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Interfaces Of The Motor

• What Is The Design Intent Of The Interfaces?
• What Information Will The Simulation Provide
  Regarding Interfaces?
• What Information Regarding Component Loading?

Inlet Port Exhaust Port
Side View
19
To Establish Fits, Evaluate Requirements For
Engines

• The Engine Must Be Capable Of 5,000 RPM and 10Hp
• Indicates Requirements For Bearings
• Indicates Loose Running Clearance Needed For
  Slider Due To High RPMs
• Indicates High Level Of Positional / Location
  Accuracy Needed In Mating Parts

20
Motor Assembly Process

• Two Sub-Assemblies Are Put Together Prior To
  Final Assembly
• Forward Crank Support Sub-Assembly
• Piston And Rod Sub-Assembly
• All Sub-Assemblies Will Require Separate
  Sub-Assembly Drawings
• This Will Drive The Family Tree

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Assemblies / Family Trees

• Assemblies And Sub Assemblies Should Reflect The
  Assembly Process
• The Lower Level Parts Should Reflect The Assembly
  They Are Used On
• The Family Tree Is A Graphical Representation Of
  The Parts Used In The Assembly And How They Are
  Assembled

22
Requirements For Engines Engine Parts

• Crank Shaft
• Connecting Rod
• Piston
• Piston Pin
• Cylinder Block
• Crank Support
• Rear Crank Case

• Forward Bearing
• Rear Bearing
• Cylinder Head
• Cylinder Head Gasket
• Screw Size 1
• Screw Size 2

23
Family Tree
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Design Documentation

• Each Designer Will Develop An Engineering
  Notebook
• The Notebook Will At Minimum Contain
• System Requirements
• Functional Requirements
• System Simulation And Power Predictions
• Assembly Section
• Sketches
• Interface Check List
• Tolerance Analysis Of Each Interface
• Separate Section For Each Part
• Detailed Sketches
• Tolerance Allocations
• Structural Analysis

25
Parts Development

• Utilize The Simulation For General Sizing Of
  Components Using The Materials Specified In The
  Interface Work Sheet.
• Flow Charts Of The Parts Are A MUST!
• Flow Charts Should Be Developed With An Eye
  Toward Assembly And Future Modifications.