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Development Process - Aerospace Engineering Design - Lecture Slides, Slides of Engineering Dynamics

University of AllahabadEngineering Dynamics

These are the Lecture Slides of Aerodynamics which includes Fundamentals of Aerodynamics, History of Fluid Mechanics, Compared to Many Fields, Fluid Mechanics, Began With Newton, Particle Dynamics, Mechanics, Particles, Momentum etc. Key important points are: Development Process, Concept Development, System Level Design, Contrasted Phase, Emphasis, Simplified Calculations, Ground Effect Project, Optimize Weight, Takeoff Distance Ratio, Clear Target Number

Typology: Slides

2012/2013

Uploaded on 03/24/2013

dhyanesh
dhyanesh 🇮🇳

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PRODUCT DEVELOPMENT PROCESS
•In last lecture examined
–Phase 1: Concept Development
–Phase 2: System-Level Design
–Contrasted Phase 1 and Phase 2 for ‘product’ vs. ‘research project’
–Check website for many more references (9 examples on line)
•Emphasis now on Phase 3: Detailed Design
•Simplified calculations to guide Phase 3
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Download Development Process - Aerospace Engineering Design - Lecture Slides and more Slides Engineering Dynamics in PDF only on Docsity!

PRODUCT DEVELOPMENT PROCESS

  • In last lecture examined
    • Phase 1: Concept Development
    • Phase 2: System-Level Design
    • Contrasted Phase 1 and Phase 2 for ‘product’ vs. ‘research project’
    • Check website for many more references (9 examples on line)
  • Emphasis now on Phase 3: Detailed Design
  • Simplified calculations to guide Phase 3

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WING IN GROUND EFFECT PROJECT

Boeing has recently taken interest in the WIG phenomenon and proposed a concept for a massive craft to meet a US Army need for a long-range heavy transport. Called the Pelican, the 500 ft (153 m) span vehicle would carry up to 2,800,000 lb (1,270,060 kg) of cargo while cruising as low as 20 ft (6 m) over water or up to 20,000 ft (6,100 m) over land. Unlike the Soviet concepts, the Pelican would not operate from water, but from conventional runways using a series of 76 wheels as landing gear. Docsity.com

EXAMPLES: EKRANOPLAN CRITERIA FOR SUCCESS

  • Example 3:
    • Achieve a transportation efficiency: >> 0.23 kg/hour/kW (modern turbo-diesel barge, ref [6] )
  • Comments:
    • A clear goal, a clear number that is a target
    • Corroborate with literature
    • How do measure that?
  • Example 4:
    • Achieve good cost effective design
  • Comments:
    • What does ‘good’ mean?
    • How do you determine if it is ‘cost effective’?
    • ‘Cost effective’ by whose standards?

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EXAMPLES: EKRANOPLAN

  • Objective/Goal Statements:
    • “Data gathered from our wind tunnel testing will hopefully allow the team to develop a system of permanent equations that will allow us to mathematically show why ground effect vehicles are more efficient and which designers can use to design WIG vehicles in the future.”
    • “Use CFD to model ground effect”
  • Comments:
    • Great idea, correlate data from wind tunnel and experiment to develop new predictive methods
    • Already been shown why and how ground effect augments lift
    • Wind tunnel testing is effective, but can some simply models be developed to understand the phenomena and make predictions?
    • How does the wing tunnel testing and CFD fit together?

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SPACECRAFT SLOSH

  • Upper-stages of expendable vehicle fleet undergo orbital maneuvers that may lead to large propellant slosh motions
  • Slosh motion can affect vehicle performance
    • Example: reorientation maneuver may cause liquid propellant to exit through pressure relief valves designated for gas venting leading to uncontrollable dynamic instability
    • Example: cryogenic liquid may splash onto hot sections of tank side walls and dome leading to large boil-off of propellant
    • Example: NEAR spacecraft interrupted its insertion burn when fuel reaction was larger than anticipated. Prevented NEAR from orbiting Eros and delayed mission
    • Example: Does Orion need baffles?
  • Models needed to predict impacts of propellant slosh for various mission scenarios
  • Limited database to benchmark CFD codes in very low-gravity (low-acceleration) environments

Lockheed Martin’s Atlas V 401

Boeing’s Delta IV Heavy

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SIMPLE SLOSH

  • Actual situation looks highly complex: droplets, wave break-up, non-uniform surface thickness, does not look exactly the same with time (transient behavior)
  • However, simple models capture the general behavior of lateral slosh
  • Two simple models (1) Pendulum Model, and (2) Spring-Mass Model Docsity.com

EXAMPLE OF CFD CALCULATION

  • CFD provides additional details
  • Important to ask whether or not you need these details for the level of fidelity required
  • Before you do a CFD calculation, ask yourself: - Why am I doing this? - Is there a cheaper, faster way to get what I want? Docsity.com

REAL NEED FOR CFD

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MESSAGES FROM SLOSH EXAMPLE

  • When natural event looks very complicated, try to look at basic physics of what is happening - Try to determine if small details are important or not - Which small details can be neglected (for the time being)
  • Spring-Mass-Damper models are extremely powerful
    • Simple to develop and solve
    • Economical in terms of time and money
  • How do you know if it is right or wrong?
  • What are the weak parts?
  • How do you test it?
  • When do you trust it?

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PROPELLER EXAMPLE

  • Many student projects have looked at variable angle propellers for UAVs
  • Various levels of complexity to model such a flow → various levels of accuracy result
  • What level of accuracy do you need?

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MESSAGES FROM PROPELLER EXAMPLE

  • When using CFD, be able to say in your report:
    • We needed a CFD model/solution to get ___________
    • The results of the CFD solution were used to __________
    • A simpler model was insufficient because it did not capture ________
  • When using a simplified model, be able to say in your report:
    • The assumptions in the simplified model are 1) __________, 2) _________
    • Assumption (1) is valid because __________
    • Assumption (2) is valid because __________
    • The model was developed to predict _________
    • The results of the model were used to _________
    • This model does not capture the details of __________

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COMBUSTION KINETICS EXAMPLE

  • Many prior senior design projects involved combustion
  • Consider Methane Combustion
  • This looks awfully simple – when written as a 1-step process
  • Equation says nothing about how long the process takes to happen
  • Approach taken by team from 2005-2006 in project goals:
    • “Model kinetics of combustion process…”

CH 4 + 2O 2 + 7.52N 2 → CO 2 + 2H 2 O + 7.52N 2 + heat

Fuel Air Products

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METHANE COMBUSTION (STEPS: 93-177)

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METHANE COMBUSTION (STEPS: 178-262)

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