The University of Arizona Hyperloop Pod Compressor & Air

Bearing System Design

DLN 8/24/15

Team Description & ObjectiveThe University of Arizona Hyperloop Team is a motivated group of three graduate and twenty undergraduate students who have an interest in the Hyperloop concept. Our team represents an engineering club on campus whose aim is to develop research and technical skills while being students at the University of Arizona.

Our team’s objective is to study and optimize the compressor and air bearing systems for a hyperloop pod design. We plan on presenting our design at design weekend but we do not intend to compete with a full pod design.

Team Members:John Donald Mangels, Irene Moreno, Philip Ciuffetelli, Jacob Grendahl, Kevin Sherwood, Mark Ernst, Rohan Mehta, Tristan Roberts, Aaron Kilgallon, Corey Allen Colbert, Jeremy Harrington, Mandy Olmut, Ryan Jensen, James Nguyen, Namrah Habib, Jacob Pavek, Patrick Portier, Harshad Kalyankar, Ryan Petronella, Jonathan Heinkel, Joel Mueting, Sean Gellenback, Ben Kaufman

Faculty Advisor:Dr. Cholik Chan

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DLN 8/24/15

System Level RequirementsName Description

Verification MethodAnalysis Inspection

Pod Constraint Pod mass shall not exceed 11,000 lbm X X

Test Track Interface Pod shall fit within the cross-sectional area of the test track X X

Operational Pod shall be moveable at low speeds when not in operation X  

Test Track Interface Pod shall utilize Operational Propulsion Interface   X

Operational Pod shall be able to come to a complete stop by use of a braking system   X

Operational Pod shall travel along the track in a smooth motion without colliding into the center rail. X  

Operational Pod shall be able to travel at Mach 0.3 without inducing a syringe effect X X

Operational Pod shall be able to levitate using air bearings between the end of the acceleration phase and the beginning of the braking maneuver X X

Pod Constraint Pod shall be powered by an onboard power system   X

Operational Pod shall be able to operate with an ambient tube pressure between .02 - 14.7 psi X X

Power Constraint Compressor and bearing support subsystems shall not exceed 1082.82 HP of onboard power X X

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DLN 8/24/15

Subsystem Level RequirementsSubsystem Description Verification Method

Analysis Inspection

Bearings Air bearing system shall interface with the test track according to the Hyperloop Tube Specification Document   X

Bearings Air bearings shall levitate the pod before the completion of 800 ft acceleration phase X  

Bearings Wheels shall support the pod during initial acceleration X X

Bearings Bearings subsystem weight shall not exceed 3700 lbm.   X

Bearings Pod shall smoothly transition from wheeled bearings to air bearings during acceleration phase X  

Compressor Compressor shall intake air moving between 0 and 334 ft/s X  

Compressor Compressor shall supply air pressurized to 3.34 psi for the air bearing subsystem X X

Compressor Compressor diameter shall not exceed 70% of tube diameter   X

Compressor Compressor subsystem weight shall not exceed 4700 lbm   X

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*Demonstrations and test verification methods were not considered because no physical pod is being built

Air Bearing & Suspension System

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Concept 1

Operation < 100 MPH

• Pod levitated according to wheel requirements• Air bearings float• Hydraulic system activated at 100 MPH

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6

45

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(1)Nose (2)Hydraulic Actuators (3)Pod (4)Air bearing Platform (5)Wheel (6)Ground

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Concept 1

ConditionNormal Operation > 100 MPH

• Hydraulic actuators activated• Wheels are retracted• Air bearings fixed• Pod levitated according to air bearing

requirements

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6

4 5

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(1)Nose (2)Hydraulic Actuators (3)Pod (4)Air Bearing Platform (5)Wheel (6)Ground

ConditionCompressor Failure

● Air bearings fed from air tank● Pod slows to safe wheel speed● Wheels extend● Pod levitated according to wheel requirements

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Concept 2 (Selected)

Operation < 100 MPH

• Pod levitated according to wheel requirements• Air bearings float• Hydraulic system activated at 100 MPH

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3

6

4 5

1

(1)Nose (2)Hydraulic actuators (3)Pod (4)Air bearing platform (5)Wheel (6)Ground

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ConditionNormal operation > 100 MPH

• Hydraulic actuators activated• Air bearings are extended• Wheels float • Pod levitated according to air bearing

requirements

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3

6

4

2

5

(1)Nose (2)Hydraulic actuators (3)Pod (4)Air bearing platform (5)Wheel (6)Ground

ConditionCompressor failure

● Air bearings fed from air tank● Pod slows to safe wheel speed● Air bearings retract● Pod levitated according to wheel requirements

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Concept 2 (Selected)

Compressor

Wheels

Air Tank

Air Bearing

Air Bearing Platform

LegendAirPhysical Connection

Pushrod Suspension

Pod Frame

Cabin/Thrust

Hydraulic Suspension

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Concept 2 Architecture (Selected)

Trade Studies Air Bearings Linear Actuators Wheels

Trade Circular Ski Hydraulic Pneumatic Solid Pneumatic

Pros -Well Understood Concept-Simplified Flow Analysis -Symmetric-Requires One Orifice

-Utilizes All Available Area-Ideally More Even Pressure Profile

-Durability -Proven Technology-Quick Reaction-Precise Control

-No Associated Fluids-Light -Clean-Small Profile

-Not Concerned With Deflating-Maintenance Free

-Low Maintenance Cost -Light weight-Non flammable gas-Higher Capacity

Cons -Unused Available Bearing Area Due To Geometry

-Requires Numerous Inlet Orifice

-No Available Designs

-Introduces fluid to the system-Large Profile-Requires Fluid Reservoir

-Limited Output Force-Internal Pressure Fluctuations-High Cost

-High Inertia-Heavy-High Replacement Cost

-Routine PressureChecks

Selected Design

Circular Single Orifice Fed Hydraulic Linear Actuators Nitrogen Filled Rubber Wheels

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Concept 2 System Design

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Nominal Operations:Drag force: 107.14 lbfCompensated by exhaust thrust of velocity magnitude X Mach

Kantrowitz Limit Concept 2: Compressor Failure

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Contingency Operations:Drag Force: 543.8 lbfDeceleration 3.15 ft/s^2 for a 551.2 lb podTime to reach < 100 mph: 59.7 secondsDeceleration Distance: 14364 feet

Compressed Air TankAssumption:No pressure loss upstream of the jet

Pressure Needed: 3.34 psiMass Flow Rate from the tank: 1.87 lb/s

Approximate stored air density: 0.161 lb/ft3

● Based on a stored air temperature of 557 K (543 F)

Approximate Volume needed: 348.03 ft3

Material: Aluminium 6061● Density: 168.56 lb/ft3

● Approximate Thickness: 0.20 in - 0.23 in

Emergency Response

Air Tank Cabin/Thrust

Air Bearings

Pressure - 23 kPaMass flow - 0.1984 lb/s

Divert all air to the bearings for the duration of emergency deceleration

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Pod to damper attachment point

Air bearing to damper attachment point

Spring

Piston guide cylinder (hydraulic fluid contained here)

Damper piston

Damper piston guide

Hydraulic fluid line connections

Hydraulic System Components

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Air bearing to damper attachment point

Hollow chamber for air bearing feed tubes

Circular air bearing

Compressor Subsystem

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Power

Tubing

Design Concept 1Legend

Data

Bridged Power

Thrust

Axial Compressor

Storage Tank

Air Bearings

Mechanical Connection

ProcessorControl System

Power

Suspension

Motor

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Power

Tubing

Design Concept 2 (Selected Design)Legend

Data

Bridged Power

Mechanical Connection

Axial Compressor 1

Axial Compressor 2

Motor 1 Motor 2

ControlSystem

Processor

Storage Tank

Air Bearings

Suspension

Thrust

Power

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Trade Studies-CompressorTradeoff Matrix

Trade Single Axial Compressor System Two Axial Compressor System

Pros • Simple 1 motor system • Uses less power• Basics compressor• Simplistic design and easier to model

• Can manipulate and change the compressor pressure ratio between the 2 stages

• High compression compared to initial conditions due to the second stage

Cons • Limited rpm movement for the same compressor ratio

• Low compression system• Less efficient

• Two drive shafts and two motors therefore higher power

• High intensity design harder to model

Selected Design Two Axial Compressor System (Design Concept 2)

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DLN 8/24/15

Material Selection• Materials for High Performance Compressor Blades

• Need stable microstructure • Want material that can be directionally solidified or want to be able to use

a single crystal for each turbine blade • Best choice material: Nickel Based Superalloy

• Materials for Stators and Shell • High specific strength • Want rigid material that is resistant to moving• Best choice material: Titanium Alloys

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DLN 8/24/15

Compressor Modeling•All compressor modeling has been done using Laux-C

•Models only design concept #1•Limited by:

•Pressure range < 7.35 psi•Mass flow rate < 110 lb/s•Can’t set constant area of compressor

•Simulations have good theoretical precision to output values

•We want to model the compressor with a specific area and be able to change the blade angle and rotational speed to create a better compression

•Switch to modeling the compressor in SolidWorks & ANSYS

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DLN 8/24/15

Compressor Model using SolidWorks

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Estimate Design Dimensions

Tube Pressure .044 Psi

Pod Cross-Sectional Area 8.61 ft2

Diffuser Entrance Cross-Section 2.15 ft2

Compressor Mass-Flow Rate 1.87 lbf/s

Exhaust Velocity 3.5 Mach

Exhaust Mass Flow Rate 0.77 lbf/s

Mass Estimate of Compressor 4629 lb

Item No. Material Description Quantity Total Mass (lbm)1 1060 Al Alloy Circular Air Bearing 15 in diameter 20 33.22 6061 Al Alloy Air Bearing Platform 15 in x 84 in 4 705.723 6061 Al Alloy Hydraulic system 4 165.044

Air bearings/Suspension:

Compressor:

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Table of Analysis

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Based on requirements, verifications, and sub-system interfaces

Requirement Model Tool

Bearing Pressure ProfilesBearing Mass Flow RateAir Bearing SystemHydraulic SystemWheel SystemEmergency Wheel SpinPod Nose Profile Compressor ModelCompressor Pressure ModelTotal Compressor Design

NumericalNumericalSolidSolidSolidNumericalNumericalSolidNumericalNumerical

ANSYS FLUENTMATLABSolidWorksSolidWorksSolidWorksExcelANSYS FLUENTSolidWorksANSYS FLUENTLUAX-C and ANSYS FLUENT

Risks Identified (R1-R6)

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Label System Failure Possible Solution(s) Risk Matrix Rating

R1

Hydraulic Suspension

Suspension won't come down/jammed upon reaching

reasonable speeds for air bearings.

Recall the pod for inspection.Minor/Moderate &

Rare

R2 Suspension locked in the "down" position.

Slow the pod down using flaps and have the pod attempt to slow down enough to where it can safely glide on the air

bearings with little to no damage to the parts. Fix upon arrival.Moderate & Rare

R3

Wheels & Wheel Suspension

Broken spring, rocker, damper, torsion bar, etc.

General maintenance inspections Insignificant & Rare

R4Broken spring, rocker,

damper, torsion bar etc. during transit

There should be multiple wheels so not much concern during transit. If this occurs during the beginning of the trip recall the pod and fix. At the end of the trip, decelerate to slower speeds

than what would be normal to pull the air bearings up and gently rest the pod on the remaining wheels. Fix at the end of

trip. Make sure that max weight isn't reached.

Minor & Rare

R5Wheels/tires worn during

transit Decelerate to slower speeds. Minor and Unlikely

R6 Wheels/tires worn General maintenance inspections Insignificant & Rare

Risks Identified (R7-R13)

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Label System Failure Possible Solution(s) Risk Matrix Rating

R7

Wheel Motor(s)

Motor(s) failure (won't work, turn on, etc.)General maintenance inspections. Before take off,

if not working, delay the schedule to fix. Minor & Unlikely

R8 Motor(s) failure during transitSlow pod down enough to where the weight can

be put on wheels without them being turned/rotated beforehand.

Minor & Unlikely

R9

Air Bearings

Damage to air bearings during transit Maintenance/repair/replacement after pod comes to a stop at the end.

Moderate & Unlikely

R10Loss of pressure to one or multiple bearings

in transit (duct failure or clogged orifice)

Decelerate to slower speeds, retract air bearings to have pod on wheels to reduce damage to the bearings. Try and figure out issue, otherwise roll

on wheels to end of trip.

Moderate & Unlikely

R11 Loss of pressure to all bearings

Pod falls on bearings; bearings will be coated with material with a low coefficient of friction; this will allow the pod slide without causing catastrophic

damage

Major & Rare

R12 Compressor Complete compressor failureCompressed air tank will supply to the bearings

with air until the pod can be slowed to acceptable wheel deployment speed

Major & Rare

Risks Identified (R14-R18)

28No use of hazardous materials in compressor design

Label System Failure Possible Solution(s) Risk Matrix Rating

R13

Compressor

Complete rotor failure Regular metallographic examinationsCompressor Braking mechanism Minor & Unlikely

R14 Duct to storage tank failureAuxiliary duct system.

High strength/reliability ductsRegular inspection of ductwork

Insignificant & Unlikely

R15

Material Failure:• Low/High cycle and thermal fatigue• Environmental exposure and foreign

object debris • Excessive tensile load on blade tip

Regular inspection of high stress partsHigh performance materials Moderate & Rare

R16

Blade Failure• High centripetal forces

• Gas flow induced steady state stress• Foreign object debris

• Thermal stress e.g: nonuniform temperature distribution

Highly accurate, symmetrical blade designHigh performance material composition

Regular blade inspectionPerformance inconsistencies require inspection

Moderate & Unlikely

R17 Entire Pod Weight Overload Check weight before takeoff. Insignificant/Minor & Rare

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R5 R7R8

R9

R1R3R6 R4

R17

R2R15

R10

R11R12

R16

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R13R14

Next StepsAir Bearings & Suspension Subsystem:

•Modeling of Nose Cone Profile•Reducing weight required to be lifted by air bearing•Flow analysis for air bearing pressure distribution•Create full model of pod assembly•Stress analysis on suspension components

Compressor Subsystem:• Develop a duct system

•Account for pressure loss due to friction•Account for temperature increase due to friction

• Model the compressor with a better modeling tool such as ANSYS• Verify and clarify tolerance ranges and dimensions of compressor• Model bypass stream of air to cool compressor to prevent overheating of system

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