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This design review discusses the development of a bearing dynamic similarity test rig to investigate the dynamics of Dresser-Rand floating ring main compressor bearings. It covers the objective, customer needs, engineering requirements, system analysis, risk assessment, and concept selection.
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P14453: Dresser-Rand Compressor Bearing Dynamic Similarity Test Rig System Design Review Rochester Institute of Technology
Project Team Rochester Institute of Technology
Stakeholders RIT: Researchers: • RIT: Industry Engineers: • Dresser-Rand: • MSD1 Team – 14453 • Graduate/Masters Students • William Nowak (Xerox) • Dr. Jason Kolodziej • Assistant Professor • (Primary Customer) • Dr. Stephen Boedo • Associate Professor • (Subject Matter Expert) • James Sorokes • Principal Engineer • Financial Support • Scott Delmotte • Mgr. Project Engineering • Point of Contact ? Rochester Institute of Technology
System Design Review Agenda • Objective Statement • Review of Customer Needs • Review of Engineering Requirements • System Analysis: • Pareto Analysis • Functional Decomposition • System Architecture • Concept Selection • Morphological Chart • Pugh Charts • Engineering Analysis & Feasibility • Risk Assessment • Milestones Chart (Updated) Rochester Institute of Technology
Objective Statement • Objective: • Develop a bearing dynamic similarity test rig to more carefully investigate the dynamics of the Dresser-Rand floating ring main compressor bearings. • Design the rig such that it can incorporate all journal bearings for the purpose of fault detection research at RIT. Rochester Institute of Technology
Customer Needs Rochester Institute of Technology
Engineering Requirements Rochester Institute of Technology
Pareto Analysis *link to House of Quality upon request: https://edge.rit.edu/edge/P14453/public/Problem%20Definition Rochester Institute of Technology
Functional Decomposition Rochester Institute of Technology
Functional Decomposition:Test Setup Rochester Institute of Technology
Functional Decomposition:Running the Test Rochester Institute of Technology
Functional Decomposition:Monitoring Bearing Characteristics Rochester Institute of Technology
System Architecture Rochester Institute of Technology
Concept Selection:System Morphological Chart Rochester Institute of Technology
Concept Selection:Concept Summary Rochester Institute of Technology
Concept Selection:System Pugh Analysis Rochester Institute of Technology
Concept Selection:Drivetrain Pugh Analysis Rochester Institute of Technology
Drivetrain Analysis:Direct Drive • Direct Drive • - Direct drive is done by attaching the motor straight to the shaft that is going to be spun. Rochester Institute of Technology
Drivetrain Analysis:Direct Drive • Direct Drive • - This can be done by using a coupling to attach two or bolting the two pieces together using a flange. The problem with both ideas is that without a dampening device on the motor or on the coupling the shaft could see outside vibrations which could affect testing results. • - Shaft alignment is also crucial in making sure that no extraneous forces are acting on the shafting while it is rotating which could cause the system to fail. Rochester Institute of Technology
Drivetrain Analysis:Direct Drive • Direct Drive Rochester Institute of Technology
Drivetrain Analysis:Belt Drives • Belt Drives • Research shows that generally different drive types can be organized into a linear range due to their properties, below is the range created as a result of the research: Stiff Soft Driveline stiffness: Misalignment allowance: Low High Shock absorption: Low High System vibration: High Low Rochester Institute of Technology
Drivetrain Analysis:Belt Drives • Types of Belt Drives • Flat belts – Used for high speed applications, used because belt slips before component damage occurs in overload scenarios. • Vee belts – Used for mid range to high speed applications, industry standard due to it’s vibration absorbing properties, allowance for misalignment, and limited slippage (~15%) due to the sloped contact surfaces. • Timing belts – Used for mid range to high speed applications, used in applications where very accurate position and speed correlation is needed. Less vibration absorption and misalignment tolerances than other belt types and the most expensive belt drive. Broken down into three types (specified later). Rochester Institute of Technology
Drivetrain Analysis:Belt Drives • Vee Belts: • Benefits: • Drawbacks: • Smooth startup – Operates smoothly at a large range of speeds and torques. • Long operation life – Well designed and maintained vee belt drives can have service live from 8,000 – 12,000 hours. • High efficiency – Vee belt drives can have efficiencies of 90-96%. • Vibration absorption – Built in belt slip, elastic properties of belt, and consistent engagement mean that driveline absorbs shocks and vibrations . • Large power and speed range – Vee belt drives can be used in a wide range of speeds and power ratings, the Journal Bearing test range is covered in this range. • Belt slip – Vee belts have both built in slip and system slip, this is based on both speed and environmental factors. This complicates the speed control system in the rig. • Expense – Like most indirect drives there are multiple precision parts required. This raises expense and system complication. • Maintenance – Continuous belt systems have the drawback that they must have an open side In the system for the removal, replacement, and maintenance of the belt. However this can be a benefit due to the system being designed for easy access. • Lubrication sensitivity – Vee belt drives are extremely sensitive to lubricants. When lubrication and other debris are introduced to the system the friction and slippage characteristics of the drive can vary greatly. Rochester Institute of Technology
Drivetrain Analysis:Belt Drives • Cogged Belts: • Benefits: • Drawbacks: • Smooth startup – Operates smoothly at a large range of speeds and torques. • Long operation life – Well designed and maintained cogged belt drives can have service live from 8,000 – 12,000 hours. • High efficiency – High efficiency, more-so than vee belts, 94-98% efficient. • Positional accuracy – Cogged belt design means high positional accuracy, in machines such as spot welding machines the positional accuracy of the belt is normally less than 1 mm. • Large power and speed range – Cogged pulleys can handle a large range of speeds and power ratings (1000KW for HTD and 600KW for GTD) • Lubrication Sensitivity – Because of the cogs on the belt there is no danger of slip caused by lubricants and other materials. • Expense – Like most indirect drives there are multiple precision parts required. This raises expense and system complication Additionally cogged drives are more expensive relative to other belt systems. • Maintenance – Continuous belt systems have the drawback that they must have an open side In the system for the removal, replacement, and maintenance of the belt. However this can be a benefit due to the system being designed for easy access. • Low misalignment tolerance – Because cogged belts are stiffer than other belt types some of the benefits of a flexible belt are lost as is the case for misalignment. A cogged belt’s tolerance for misalignment can be as low as 10% that of an equivalent vee belt. Rochester Institute of Technology
Drivetrain Analysis:Belt Drives • Example Vee Belt calculation: Assuming a speed ratio of 2:1 with a output of 4000rpm the belt required would be (Bando USA): 1 std. A transmission belt pulley 1: 10.40 in OD pulley 2: 5.20 in OD Rochester Institute of Technology
Concept Selection:Load Application Pugh Analysis Rochester Institute of Technology
Load Application Analysis:Hydraulic Cylinders • Benefits: • Load Accuracy • Required Analysis (Incompressible Fluid) • Drawbacks: • Safety • Maintenance • From PRP and Markus’s Thesis: • Up to 900lbs (4000N) applied force • Up to 2000 rom shaft speed (33Hz) • Journal to sleeve clearance: 35 to 95 microns • Compressor Operating Rpm: 360rpm (Dr. Kolodziej) Rochester Institute of Technology
Load Application Analysis: Hydraulic Cylinders • Parker Electro-Hydraulic Actuator (EHA) • Hybrid combining benefits of hydraulic cylinder and electric servo • Self-contained unit • Speed and Load Range • Size Rochester Institute of Technology
Load Application Analysis: Hydraulic Cylinders • Calculations for Parker EHA (w/ Motor B and 0.327 gear): • Distance for Piston to move (conservative): • 95µm=0.00374"; 0.00374"*2= • 0.00748“ ≈0.01" (cushion) • Piston Speed from Graph ≈ 2.9in/s • Cycle time: • (0.01in)/(2.8 in/s)*2(extend & retract)= • 0.007143 secs/cycle • Actuator Frequency: • 1/(0.007143 secs/cycle)= • 140 cycles/second = 140Hz • Compresser Frequency: • 360rpm/60=6rps(rotation=cycle) =6Hz • Requested Frequency: • 2000rpm/60 = 33.3Hz Rochester Institute of Technology
Load Application Analysis:Pneumatic Cylinders • Pneumatic Load Application: • Benefits • Pneumatic cylinders are relatively inexpensive • Compressed air is readily available within most lab spaces • Disadvantages • Nonlinear operation, specifically when direction of motion changes • Overcoming resulting issues creates a complicated controls problem • Below is a diagram for a twin servo valve control setup for a pneumatic cylinder as proposed by J. Falcao Carneiro, F. Gomes de Almeida in their paper Using two servo-valves to improve pneumatic force control in industrial cylinders. Rochester Institute of Technology
Load Application Analysis:Pneumatic Cylinders • The following graph, from their paper, demonstrates the issues related to pneumatic load control. • This problem is accentuated by the fact that we will require high loads ( ~ -3000 to 4000 N ) at very low displacement ( Less than 0.5 mm ). Force (N) Velocity (m/s) Rochester Institute of Technology
Load Application Analysis: Pneumatic Cylinders • Control System for Pneumatic Loading • Requires two servo valves per cylinder • System needs to react in advance in order to redirect air in time to maintain proper shaft loading • Controls programming will be time intensive • Hydraulic systems do not suffer from issues with compressibility, and therefore react better to high frequency, low displacement changes Rochester Institute of Technology
Additional Engineering Analysis • Structural: • Shaft stress & deformations • Mounting component stress • Support bearing analysis • Lubrication System: • Required pressure analysis • Flow rate • Data Acquisition System: • Sampling rate • Power Requirements Rochester Institute of Technology
Proposed Layout 1: Direct Drive Shaft Coupling Bearing Shaft Drive Motor Support Bearings Load Block / Custom Bearing Housing Test Stand Test Bearing Oil Sump Hydraulic Cylinders Rochester Institute of Technology
Proposed Layout 2: Belt Drive Belt System Drive Motor Support Bearings Load Block / Custom Bearing Housing Bearing Shaft Test Stand Test Bearing Oil Sump Hydraulic Cylinders Rochester Institute of Technology
Risk Assessment Rochester Institute of Technology
MSD1 Milestones Chart Rochester Institute of Technology
Problem Definition [09/10/13]: • Define problem • Define customer requirements • Define engineering requirements • Plan project • System Design Kick-Off [09/17/13]: • Problem definition completed • Begin concept development • Decomposition analysis • Risk assessment • Benchmarking concepts • System Design Review [10/01/13]: • System design completed • Meet with guides/panels/stakeholders • Select feasible system • Sub-System Design [10/08/13]: • Subsystem design and interactions • Requirement flow-down • Next level of decomposition analysis • Feasibility analysis • Subsystem Design Review [10/24/13]: • Subsystem design completed • Meet with guides/panels/stakeholders • Detailed Design & Component Selection [10/31/13]: • Fully completed drawings • Component list • Any FEA/Simulations • Risk assessment • Benchmarking plans • Preliminary DDR [11/19/13]: • Meet with guides/panels/stakeholders • Ensure that all design components are complete MSD1 Milestones Rochester Institute of Technology
Develop sub-sys and interfaces [10/8/13]: • Consider alternatives, feasibility, requirement flow-down • Refine requirements, needs vs. spec mapping • Perform next level functional decomposition • Perform next level of risk assessment • Second-order Analysis (PoC) [10/17/13]: • Manual formulation/analysis • CAD modeling • FEA analysis/simulations • Review feasibility • Develop/update test plan • Prepare presentation (PoC, pre-DDR) [10/22/13]: • Action items from sub-system design and impact on project • Compile modeling/FEA • Review and analysis of function flow-down within sub-systems • Feasibility demonstrated by PoC • What is the requirement test schedule • Has the design been adequately reviewed? MSD1 Sub-System Design Milestones Rochester Institute of Technology
Questions? Rochester Institute of Technology