Determining the Fatigue Life of Aero-Engine Blades

Transcription

1 w w w. s c i t e k c o n s u l t a n t s. c o. u k Determining the Fatigue Life of Aero-Engine Blades SCITEK Consultants Ltd Martin Haste, Florian Faurillou, Jon Bates, Marios S Christodoulou 4 th November 2014 NI Days 4 Nov 2014 London NI Days 4 th Nov 2014 London

2 Who is SCITEK R&D Services Fluid Mechanics CFD, LDA, PIV, Spays Rig Design & Manufacture CAD + Stress Analysis, Instrumentation Instrumentation+ Control Systems Software, Sensors, Signal processing, Test rig infrastructure Image Analysis X Ray Analysis, Strain gauge Calibration, Neutron Radiography Small Gas Turbine Test Beds RR Gnome& Viper, Wren 17 years old, and privately owned, 20 staff, 2 Vacancies Based in Derby in the Midlands National Instruments Alliance Member ISO 9001 and OHSAS18001accredited RR SABRE approved Customers mainly in Aerospace Partners in several TSB and EU funded projects

3 Capabilities and Expertise Design of Rigs Design and modelling Unigraphics and SolidWorks Stress Analysis using Finite Element- FEMAP Thermal Analysis Frequency analysis of Structures Flow Modelling CFD OpenFOAM, ANSYS Fluent Instrumentation Expertise with all types sensors, noise, flow, temperature, pressures, acceleration, vibration, position, load, imaging, etc Data Acquisition, Control, and Signal processing Expertise on all National Instruments Hardware Expertise in LabView Software NI Alliance Member Positioning Systems NDT X-ray imaging and inspections Neutron radiography Corrosion, liquid passages Ultrasonic inspection Delamination, material thickness Health and Safety Experience in providing DSEAR compliant rigs Experience with Pressure Equipment Directive Experience with Low voltage Directive and CE Marking

4 Blade Fatigue Background An engine consists of rotating blades. Compressor blades - Cold Turbine Blades - Hot For each rotating stage there is a stationary guide vane Flow of air past rotating blades is fundamental to the operation of the engine

5 Blade Vibration NI Days 4 th Nov 2014 London Blades are cantilevered and as air flows past them they vibrate Very similar to a tuning fork Vibration eventually leads to fatigue Fatigue life of blades is fundamental to aircraft safety Fatigue life of blades is also fundamental to aircraft operating costs an engine needs to be removed to replace blades. Compressor blade Temperatures up to 700deg C Turbine blade temperatures well above 1000 deg C

6 Need to determine Fatigue life NI Days 4 th Nov 2014 London OEMs need to know the fatigue life of every type of blade in an engine. Weakest link is the blade with the shortest life Fatigue life is determined during development of new engines For quality assurance Fatigue life is also constantly checked to ensure manufacturing processes are consistent Thus Need for a system to measure no of cycles before a blade fatigues

7 Airjet Excitation Method for Fatigue Life NI Days 4 th Nov 2014 London Flow nozzle for excitation with flow controlled with Norgren valve via V to P converter. Amplitude measured by a camera or by laser triangulation probes Frequency measured by a microphone Technique first demonstrated in the 1960s High speed air is flowed over a stationary blade Blade oscillates in a similar fashion to a turning fork Amplitude of vibration (A) at tip measured non contact sensor Frequency of oscillation (F) measured non contact sensor Keep AxF constant whilst counting cycles Blade clamped in fixture, normally by a hydraulic clamp to replicate CF loads.

8 SCITEK Airjet System OEMs tended to develop in-house systems SCITEK system first one to be commercially available Low volume high value product

9 Airjet Exciter System Overview Airjet Nozzle Microphone High air flow capacity pressure regulator Test Cell Compressed air supply Up to 0.3Kg/s Laser Vibrometer Other Type of Amplitude sensor NI Compact DAQ Gige Camera 1 ADC Module 3 inputs Gige Camera 2 Ethernet Hub DAC Module Blade holder and Clamping mechanism Voltage controlled pressure regulator Desktop PC or Laptop Shop air supply 7 to 8 bar max

10 Low Volume high value product Limited Market Too costly to develop in-house electronics Why Based on NI Hardware Ni Support ensures product longevity Hardware and software driver upgrades by NI SCITEK software developed in Labview SCITEK concentrates on system functionality ease of operation provide custom hardware to suit blade geometries Setting up a turnkey test facility

11 Measurement of Amplitude Video camera 25 frames per second High Magnification lens Dynamic measurement of amplitude of oscillation at top of blade Air jet excitation Solid blade holder White lines are blade features that oscillate System varies air pressure to change amplitude of oscillation Automated test ensures constant Amplitude x Frequency System Records measured amplitude at tip of blade. Blade Tip amplitude is calibrated using a resolution screen Image can show other modes of oscillation System can be used for very large and very small blades

12 Software Features PID auto tuning Blade vibration characteristics are different. Thus if our system is to be used to measure any blade size. System versatility is very important. PID autotuning is a key feature of the system for smooth AxF transitions

13 Software Features Experiment Monitoring 1 Experiment Progress tests can last for many days Automatic Step changes in AxF levels

14 Software Features Experiment Monitoring 2 Graphical view of experiment progress Post processor of experimental results

15 Other System Features Camera Calibration Screen for Amplitude measurement Document generator for traceability of blade serial no and test results Post processor/viewer of results

16 Conclusions, Outlook and Demo SCITEK Airjet exciter system now developed and commercially available NI Hardware/software ensures longevity and supportability of this product Future development will be to produce a forced Airjet system where the air excitation frequency is not constant but pulsed

17 Short Demo of Our System Demo system for Ni Days Airjet replaced with a speaker (Lower oscillation amplitude) Demonstrate dynamic amplitude measurement using camera and automatic AxF steps

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