Simulation of Centrifugal Casting - Siemens · Simulation of Centrifugal Casting via STAR-Cast Santhanu Jana, Access e.V., Aachen Centrifugal casting STAR-Cast‘s modelling basis

Simulation of Centrifugal Casting via STAR-Cast Santhanu Jana, Access e.V., Aachen

Centrifugal casting

STAR-Cast‘s modelling basis

Motivation for centrifugal investment casting

Centrifugal investment casting of

● Low pressure turbine blades

● Turbocharger wheels

Future work

Talk overview

Centrifugal forces distributes the molten material in the mould

Rotation axis may be horizontal, vertical or inclined

Preferred for high quality cast parts

Rolls, nozzles, wheels, jewellery, etc

Casting materials: iron ,steel, alloys of Aluminium, Copper, Titanium etc

Top rollers

Casting

Mould Coating

Liquid metal Bottom rollers

Introduction to centrifugal casting

Schematic of horizontally rotated

bimetallic casting

Modelling basis in STAR-Cast

Coupled flow and solidification model : Multi phase approach: gas, liquid and solidified metal

● HRIC: ensures sharp resolution of free surface, entrapped gas bubbles

● Porous walls: Escape of gas through shell moulds

● Interfacial forces: Surface tension and wetting angle effects

● Rotational forces : are modeled based on rotating frame of reference

● Moving grids: to model crucible tiling and pouring into the funnel

Polyhedral meshes: for complex geometries and multiphysics simulations

Material data: Comprehensive and fully documented data dedicated for casting simulation

High performance computing: Scales almost linear on parallel machines down to 10.000 cells per processor: STAR-Cast Power Version

STAR-Cast‘s modelling approach

Advanced liquid-solid state transition model

● Resistance to flow is a function of secondary dendrite arm spacing

Liquid Mushy Solid

fL= 0.0 fL= 0.3 fL= 1.0

STAR-Cast‘s modelling approach

Motivation for centrifugal investment casting

Aero-engine manufacturers are introducing using new light weight materials

Intermetallic TiAl alloys

● 50% lower weight compared to conventional Ni-based alloys.

Centrifugal investment casting can deliver

high quality requirements

Ni basis Vs. TiAl blades

Casting of TiAl components with centrifugal investment process

But a difficult material to cast ● Potential of misrun ● Components like LPT blades have trailing edges of around 0.5 mm

Near-net-shape parts manufacture of Titanium Aluminides

HPC Vanes LPT Blades

Medical Implant Turbocharger Wheel

Centrifugal Investment Casting of Low Pressure Turbine (LPT) Blades

Typical casting defects in LPT blades

Misruns Porosity

The foundry engineer faces an uphill task!!!!

Gas entrapments

Ceramic Particles

Ceramic breakouts

Hot tearing

Induction Skull Melting Copper Crucible

Tilting

Melt Separation valve

(open) Heating

box Melting chamber

Casting chamber

Sprue

Melt distributor

Rotating table Rotation

Process characteristics

Two chamber system

Melting capacity: 10.0 kg (optional 25 kg)

Rotation speed:0-400 rpm

Mould filling in 1.5 seconds

Centrifugal investment casting LPT Blades

STEP 1: Simulate the crucible pouring process moving grids

Metal flow Velocity field

Simulation of the pouring process

Wetting

Simulation of the pouring process

Obtain inlet mass flow rate for the casting cluster Optimize the pouring process

Skull weights on funnel Funnel outflow

STEP 2: Simulate the casting cluster

● Generate the shell mould and mesh

● Apply inlet, initial and boundary conditions

● Use appropriate time step size (around 1.0e-4s)

● Solve on a high performance computing cluster

(With around 72 processors total computing time is 4

days)

Objectives: ● Predict misruns : i.e., if a fully filled blade is achievable or not

Simulation of the casting cluster of LPT blades

LPT blade Distributor

Runner Ingates

Inlet

Typical casting cluster of LPT Blades

Rotating at 200 RPM

Polyhedral mesh on shell mould

Total mesh size :3 million cells

Generation of shell mould and mesh

Simulations of casting cluster

Rotating at 200 RPM

Simulations of casting cluster

Rotating at 200 RPM

Result from Casting Trials

Comparison of casting trials and simulation predictions

Final outcome!!!!

Simulations

Casting designs

Next time anyone flying on an aircraft fitted with these blades be assured it has been developed using state-of-the-art tool STAR-Cast

Centrifugal investment casting of TiAl turbocharger wheels

Centrifugal investment casting TiAl turbo charger wheel

Centrifugal investment casting furnace, shell mold and turbocharger wheel

Centrifugal investment casting TiAl turbo charger wheel

Process characteristics

Melting capacity: 2.0 kg (max)

1 Chamber process

Wrapping around parts slows down the solidification

process

Ceramic shell mold calculated using the STAR-Cast shell mold generator

Centrifugal investment casting TiAl turbo charger wheel

Centrifugal investment casting TiAl turbo charger wheel

Centrifugal investment casting TiAl turbo charger wheel

spinning

Multiple frame of references coupled with solidification

Centrifugal casting of multiple alloys

Particle tracking during mould filling

Coupling to thermomechanics

Future work

Special Thanks !!