Successful Applications of CFD within the Aircraft Certification Process TLG Aerospace. Unrestricted Siemens AG 2018

Transcription

1 Successful Applications of CFD within the Aircraft Certification Process TLG Aerospace Unrestricted Siemens AG 2018

2 About TLG Aerospace TLG is an engineering services company providing design, analysis, test, and certification expertise to help bring client products to market. TLG uses Siemens STAR-CCM+ and NASTRAN to develop full-vehicle certification models for loads, flutter, and handling qualities. FAA Designated Engineering Representatives (DER) on staff: Loads, Flutter, Flight Analyst, Stress. Core expertise in aerodynamics, structures and design. High-end analysis capabilities include fluid-structure interaction, dynamic free-body interactions, non-linear structural dynamics. Robert Lind, Director of Engineering, FAA Flutter DER Successful Applications of CFD within the Aircraft Certification Process TLGAerospace.com 2

3 Analysis in the Certification process The FAA requires certification by test, or by analysis that is validated by test. Method of Compliance varies for different regulations. CFD plays an increasing role in expediting the certification process and lowering costs. Reducing the number of flight test conditions Enabling safer flight testing by predictive analysis of potential hazards Enabling test to lower load levels with analytical extrapolation to higher load levels Successful Applications of CFD within the Aircraft Certification Process TLGAerospace.com 3

4 Full Vehicle Models FAA loads and flutter analyses require full-vehicle models coupling aerodynamics, mass properties, structural dynamics, and flight controls. Proper modelling of fluid-structure interaction is a critical requirement for certification. Industry standard techniques for rapid and accurate FSI over the entire flight envelope, steady and unsteady. The integrated full-vehicle model is ultimately validated by flight test and must be shown to be accurate or conservative. Aeroelastic Model Aerodynamics CFD, Low Order Methods, Wind Tunnel, Handbook Validation by pressure, strain measurements in flight test Mass Properties CAD, Weights Bookkeeping Validation by weighing Full Vehicle Model Structures Finite Element Analysis, Handbook Validation by GVT, static load in ground test Flight Controls Flight Control Laws Validation by integrated sim and flight test Successful Applications of CFD within the Aircraft Certification Process TLGAerospace.com 4

5 How is CFD Consumed? CFD results are mapped to a reduced order aerodynamic model within an aeroelastic process: Doublet Lattice Method (DLM) in NASTRAN is typical. Linear and non-linear aerodynamic treatments available. Manipulated to ensure accurate or conservative predictions from the full vehicle model. Reduced order model will produce steady and unsteady flexible and rotary aerodynamics. A local linearization from CFD is used to scale the reduced order model. Final aeroelastic model will reproduce full-vehicle integrated and distributed aerodynamics from CFD when run in rigid mode. Successful Applications of CFD within the Aircraft Certification Process TLGAerospace.com 5

6 How is CFD Consumed? Calibrated aeroelastic model will yield a converged, trimmed, aeroelastic solution in seconds. Wing span-load scaling for a transport Airplane Each curve represents a unique wing station. Flying surfaces scaled to match sectional properties on a spanwise basis. Pressures can be projected to reduced order model, or mapped directly. Extracting Pressure Load on a Windscreen and Fixed Leading Edge Segment Successful Applications of CFD within the Aircraft Certification Process TLGAerospace.com 6

7 CFD or and Wind Tunnel Wind Tunnel testing remains a critical tool for aerodynamic configuration development and handling qualities assessment. Wind tunnel best for incipient separation regimes (e.g. high-alpha and Sideslip handling qualities). CFD good for moderate-alpha and sideslip and detail flow-field investigation. A hybrid CFD and Wind Tunnel strategy will often yield the best results. Both data sources can be assimilated into the full vehicle model. CFD is increasingly used in a Virtual Wind Tunnel mode to develop large aerodynamic databases for certification. Where accurate or conservative linearization can be performed. Enabled by innovative licensing strategies and breakthroughs in elastic cloud computing. TLG uses STAR-CCM+ to generate databases with thousands of cases. Successful Applications of CFD within the Aircraft Certification Process TLGAerospace.com 7

8 Modern CFD Productivity Notional Notional Assumptions: Accuracy of each approach assumed suitable for the application. Model Costs: LSWT $165k, HSWT: $315k, CFD (Legacy/Now): $15k / $15k Usage Rate (per Hour): LSWT: $600, HSWT: $4500, CFD (Legacy/ Now): $250 / $100 Engineers per Hour: LSWT: x2, HSWT: x3, CFD (Legacy/ Now): x1 / x1 Productivity: LSWT: 800 cond/day, HSWT: 600 cond/day, CFD (Legacy/ Now): 20 / 80 cases/day Disclaimer, calculations may differ for your specific application. Large databases can be run in STAR-CCM+ today at a fraction of the cost and schedule of legacy methods and wind tunnel testing. Successful Applications of CFD within the Aircraft Certification Process TLGAerospace.com 8

9 100% Spot Instances Shared File System Mounted to Head (NFS to Compute Nodes) AES 256 Encryption Elastic Computing with P.O.D. Licensing Virtual HPC Environment Cluster ABC ABC01 Head Node ABC02 Compute ABC03 Compute ABC04 Compute ABC05 Compute Large RANK Security Group Gateway Secure Elastic Cloud Computing Multiple Clusters Cold Storage Simple Storage Secure Tunnel Power-On-Demand licensing and elastic cloud computing eliminates the serial execution bottleneck. Unlimited throughput in theory. No technical limitation to running vast numbers of CFD cases simultaneously. Practical limitation is human resources. Scalable to large models. Elastic computing allows most models to be run in < 1-hour, regardless of model size. Secure Terminal On-premise Sync Successful Applications of CFD within the Aircraft Certification Process TLGAerospace.com 9

10 Other Applications of CFD in Certification Pressure loading on secondary structures, fairings, antennas and radomes. Non-impact assessment to original type compliance due to modifications. Flap effectiveness in Star-CCM+ validated against OEM test data Internal flows of inlets/outlets/ducts. Air-data system location. Reduced Vertical Separation Minimums (RVSM) performance. Particle trajectory analysis for safe separation of ice and non-damage tolerant structures. Static source error analysis in Star-CCM+ validation in flight test Ice accretion analysis. Cavity Resonance Analysis in Star-CCM+ Non-impact Assessment Successful Applications of CFD within the Aircraft Certification Process TLGAerospace.com 10

11 Summary CFD is increasingly used in the certification process as a supplement or replacement to wind tunnel testing. CFD informs the full vehicle model that is ultimately validated by test and shown to be accurate or conservative. Power-on-Demand licensing and elastic cloud computing enables large numbers of CFD simulations to be performed in a short time and for low cost. Siemens STAR-CCM+ is routinely used for aircraft certification at TLG Aerospace and has contributed to receipt of numerous FAA approved Supplemental Type Certificates Successful Applications of CFD within the Aircraft Certification Process TLGAerospace.com 11