Multi-Physics

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Multi-domain interactions – Fluid, thermal, electromagnetic, structural, dynamics …
Complex interactions, often with feedback loops, can occur which affect the transient operation, performance and durability of machinery. In general these interactions aren’t strong and can be ignored, leading to simplification in the design and analysis process.

Sometimes however the simulation of these phenomena is the only way to achieve the required system performance.

PTL has the experience and capability necessary to understand when multiphysics modelling is required and to devise a program of work to model these interactions in the most expedited way.

A fitting example of a multiphysics problem is the hydraulic operation of the engine poppet valves, which control the breathing of an internal combustion engine. The use of hydraulics to control the timing of the valve opening events results in improved engine fuel economy and emissions. These advantages however, can be only achieved if the system performs identically for all the engine cylinders.

The hydraulic valvetrains are controlled through electromagnetic solenoid valves, which control the flow and pressure of the hydraulic fluid which in turn open and close the engine poppet valves. Tolerances in the components, pressure waves in the oil passages, mechanical vibrations and other factors can alter the opening and closing timings of the poppet valves from one cylinder to the next.

Non uniform in valve opening timings can lead to increased engine emissions and require increased size catalysts, cost, engine mass and fuel consumption.

The use of multiphysics modelling techniques applied to all the engine valvetrains provides the means to understanding and quantify the important features of a successful design.

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3D Finite Elements Analysis (FEA)

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Structural and thermal analysis of complex mechanical systems

The analysis team uses the latest ANSYS mechanical software environment, together with knowledge of APDL and FEA best practices to support the design and development of components for complex mechanical systems, or as standalone analysis contracts. Typical projects include:

  • Stiffness/mass trade-off optimisation for best dynamic performance
  • Analysis of assemblies with contacts
  • Stress and fatigue analysis of componenets and assemblies
  • Steady state and transient thermal analysis
  • Thermodynamics

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    Performance, energy tracking, efficiency

    Our thermodynamics expertise was born from our work on advancing engines performance, efficiency and emissions, but can be applied to other systems and machines where the exchange of thermal, mechanical or chemical energy occurs.

    This type of analysis is often fundamental in establishing the merits of novel ideas and in specifying functional requirements, mechanical loads for the machine components and subsystems, ultimately allowing a product to achieve competitive performance & efficiency levels. It is performed as a standalone piece of work or as part of a larger design project

    The commercial program GT-Suite is our main analysis tool, often complemented by our in-house software for specialist tasks.

    The work undertaken includes:

    • Assessment of thermodynamics fundamentals
    • Thermodynamic cycle simulation or full system modelling, including heat transfer, wall temperatures, exchangers and energy tracking
    • Steady-state and transient simulations
    • Heat pumps
    • Rankine and Stirling cycles
    • Compressed air storage and reuse (Air hybrid systems)

    Computational Fluid Dynamics (CFD)

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    Analysis of fluid flows in complex machines

    CFD analysis is performed using the Convergent Science software Converge. Although a relative new comer to the CFD market, PTL & its partner SwRI have been using Converge on client project work for many years including prior to it being a mainstream product.

    As such our team has experience of applying CFD to many analysis types including:

    • Steady state flow for individual components or systems such as engine ports
    • Flow visualisation & analysis
    • Combustion
    • Moving boundaries for non-reciprocating machines such as rotary engines

    CFD can also be applied to other areas that PTL work within including pumps, FIE and cooling & lubrication circuits. Additionally STAR-CCM + is used by our partners at SwRI for clients who require model compatibility

    Engine Performance Simulation and Tuning

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    Engine performance simulation analysis at all stages of project work

    The analysis team at Powertrain Technology use 1-D engine performance simulation analysis at all stages of engine performance simulation & tuning project work. The analysis can be a standalone piece of work or be used to provide input data as part of a larger analysis. Typically GT Power is used to perform the analysis but we have extensive experience of alternative software packages such as Wave.

    Types of analysis undertaken include:

      Model construction & validation

      • Matching model to real engine test data
      • Best practice models using engine benchmark data for concept evaluation

      Simulation of engine only for system tuning:

      • Valve sizing and timing strategy and optimizations
      • Turbo sizing and matching
      • Manifolds and associated ductwork
      • Engine downsizing

      Full engine system including cooling, lubrication, valvetrain & mechanical systems circuits

      • Heat transfer characteristics such as for Combined Heat & Power (CHP)
      • Engine performance maps generation for vehicle analysis, often using fast running models

      Novel engine design evaluation

      • Rotary engine
      • Split Cycle
      • Stirling

    Vehicles Performance and Economy Simulation

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    Conventional, Hybrid and Electric – Modular approach

    The PTL analysis group has extensive experience in the simulation of vehicle performance and fuel economy, performed either using in house software or the commercial program Gt-Suite.

    In the analysis all key component properties like efficiencies, tire radius, grade, curvature, road & environment can be accounted for together their evolution during simulation if required.

    Our modular approach allows the simulation of all vehicle sizes and architectures (car, truck, motorcycle, bycicle), using swappable modelling blocks. The merits of alternative transmission setups can be evaluated and ranked, being manual, automatic, dual clutch or infinitely variable.

    Key inputs for the analysis are the map of engine fuel consumption versus engine speed and load as well as the transmission efficiency in the various gears. Depending on the project needs PTL can generate these maps by either simulation, often using fast running models, or by suitably modifying maps from our database of test data.

    As an alternatively and when dictated by the need for more in depth analysis of interactions or transient operation, a fully featured or fast running GT-Power engine model can be run coupled with the vehicle model over the drive cycle.

    Typical uses for this type of vehicle driving simulation include:

    • Sizing of engine capacity to achieve the required performance and fuel economy targets
    • Ranking of fuel economy potentials of candidate vehicle, engine and transmission technological improvements
    • Accounting for energy loss from individual systems and components
    • Gear ratios and shifting strategy optimisation for driveability, performance or fuel economy
    • Scheduling of operating modes of Hybrid and electric vehicles operation

    Scheduling of operating modes of Hybrid vehicle, where the timings and amount of stored energy to use, as opposed to relying on the internal combustion engine, need to be optimized over a drive cycle to achieve best fuel economy. PTL have developed a fast solving optimisation algorithm, for this class of problems, capable of identifying the optimal mode switching strategy and determining the maximum potential of each powertrain/vehicle configuration.

    Valvetrain Design and Analysis

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    For all engine types and applications – High speed and VVA specialists
    Valvetrain design and development is a core skill set for the PTL analysis team, having worked on a variety of systems, covering a large number of engine types and applications. Capabilities include:
    • Thorough understanding of functional requirements
    • Innovative thinking: > 20 awarded patents (assigned to clients)
    • Dynamic analysis – Extensive experience
    • GT-Suite, Simulink and Adams – Matlab post-processing
    • Modelling of mechanical and hydraulic systems and components
    • Broad range:
      • Conventional valvetrains (cars, trucks, high speed engines)
      • Dual lift & Continuous VVL
      • Camless: Hydraulic,elcectric & Pneumatic
      • Fast acting & lost motion (dwell cam)
      • Conventional coil springs
      • Gas and other unconventional springs
    • Conventional and innovative materials, coatings and manufacturing processes
    • Experience in Rig testing: architecture, instrumentation, test planning, test execution & correlation
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    Analysis of Belt, Chain or Gear Drives

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    Design and analysis of belt, chain and direct drives for engines and machinery

    The analysis team can provide dynamic models of a range of drives for various applications. Previous experience includes design and implementation of FEAD and belt driven valvetrains for development engines, as well as the design and specification of drives for production intent engines.

    Piston and Ring Pack Analysis

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    Multiphysics analysis of piston, ring pack and cylinder interactions
    The team has recent project experience of piston assembly dynamic analysis for engine development support. Capabilities include:
    • Piston secondary motion, tilt and eccentricity
    • Piston lubrication and friction
    • Ring radial and twist motions
    • Ring tension and groove pressure forces
    • Ring hydrodynamic and asperity forces
    • Ring face oil film hydrodynamics/mixed lubrication

    Mechanical Analysis of Engine Components and Subsystems

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    Valvetrain, Crankshaft, connecting rod, piston, cooling and lube systems, …
    The analysis team at Powertrain Technology can perform sizing of engine subsystems and components, being at the initial stage of a project when many details still have to be defined and preliminary dimensions need to be provided as inputs to the design, or later on, when the design is being finalised and confirmation is needed of the design elements to work as intended. These skills can be also applied to projects involving the diagnosis and rectification of problems and failures. Typical analyses include:
    • Kinematic and dynamic analysis of valvetrain
    • Piston and connecting rod bearing sizing and fatigue analysis
    • Crankshaft bearing sizing and oilfilm analysis
    • Crankshaft sizing for fatigue strength. This involves flywheel sizing and the tuning of Torsional Vibration (TV) dampers, if necessary.
    • Dynamic analysis of accessory (FEAD) and timing drives
    • Cooling and lube circuits analysis and specification
    • Analysis and sizing of critical fasteners (gasket sealing, torque transmission, bearing clamping, etc