Parametric Geometry for Propulsion-Airframe Integration

Transcription

1 Parametric Geometry for Propulsion-Airframe Integration NASA NRA NNX11AI70A Topic 2.2 Russell K. Denney Jimmy C. Tai Dimitri N. Mavris Georgia Institute of Technology Atlanta, GA 30332

2 Outline Objective and Background Approach Current Progress Inside Track Outside Track Model Problems Observations from Year 1 Year 2 Work Plan 2

3 3 Parametric Aircraft (VSP) Aero Generation Background Cycle Modeling (NPSS) Mission Analysis (FLOPS) Other System Metrics Our typical design process starts with the engine cycle and a vehicle representation, which is used for drag prediction. Thrust, fuel flow, and drag data are used for the mission analysis and analyses for other system metrics, such as noise and emissions.

4 4 Parametric Aircraft (VSP) Background Cycle Modeling (NPSS) Flowpath Design (WATE++) Aero Generation Mission Analysis (FLOPS) Other System Metrics In recent years we have begun adding engine flowpath design to the process, to ensure our engines are buildable and to provide better data for weight, noise, and emissions predictions

5 Parametric Aircraft (VSP) Background Cycle Modeling (NPSS) Flowpath Design (WATE++) Aero Generation Mission Analysis (FLOPS) OpenVSP Engine Flowpath New tools such as OpenVSP and OTAC for the engine flowpath will make it possible to bring more physics into the conceptual design process Other System Metrics 5 Higher Fidelity Design/Analysis Tools

6 Traditionally most resources have been committed during the last half of the development process Late design changes are difficult and expensive However the fate of the program is often decided by the decisions made early on Development risk and cost may be reduced by improving the capability of the conceptual phase Motivation Panchenko et al, Preliminary Multi-Disciplinary Optimization in Turbomachinery Design, RTO AVT Symposium on Reduction of Military Vehicle Acquisition Time and Cost through Advanced Modelling and Virtual Simulation, Paris, France, April 2002, RTO-MP-089 6

7 7 The Big Picture Iterative Design by Analysis Process Conceptual Design Tools Analysis Tools Aero Structure Noise etc Intended to run quickly Use simplifying assumptions Solve simplified equations Usually 1-D or 2-D geometry Model more detailed physics Usually require 3-D geometry How to connect the design and analysis tools to ensure a consistent geometry is analyzed by each discipline?

8 8 The Big Picture Analysis Tools Aero Conceptual Design Tools OpenVSP Structure Noise etc OpenVSP provides: 3-D Design DOF Visualization Geometry Standard o Ensures consistent geometry is analyzed by all disciplines o Geometry is updated with each iteration

9 Program Plan The research is divided into two main tracks: Parametric Variation of Inlet and Nozzle Geometry Improved estimation of installation effects, throttle-dependent drags, and engine-airframe interactions Address unique problems related to parameterization of advanced inlets and nozzles, which may be square or round, straight or serpentine, and may have special geometric features such as chevrons Parametric Variation of the Entire Engine Flowpath Produce a 3D representation of the complete engine flowpath geometry, which will permit more detailed analyses of unconventional engine cycles Identify specific requirements for engine fan and turbine parameterization for successful interfacing with higher-order, physicsbased tools for noise and performance analyses 9

10 10 Current Progress Inside Track 3-D Engine Flowpath Design

11 11 OpenVSP in the Engine Flowpath Design Process 2-D Flow Path Defines Basic Shapes (Areas, Radii, Lengths, etc.) Cycle and Flow-path Design NPSS/WATE++ Higher Order Analyses 3-D Geometry Tool Adds Design DOF Vehicle Sketch Pad Rhino3D Meta-Geometry Aero Codes, Structural Analysis Codes, etc Higher Order Analyses

12 12 NPSS/WATE++ NPSS is an object-oriented programming environment for modeling aircraft turbine engines Traditional 0-D thermodynamic cycle modeling Zooming capability to link with higher fidelity design and analysis codes WATE++ is a collection of NPSS objects for predicting the engine flowpath dimensions and weights Uses thermodynamic cycle data as input Simplified stress analyses & empirical relationships to size the components

13 OpenVSP Sockets Each WATE++ component has been modified to include a socket or subelement to generate the XML code for OpenVSP Simply include the socket when the element is instantiated in the WATE++ config file Defines additional OpenVSP parameters for 3-D geometry that WATE++ doesn t care about NPSS run file Runs NPSS cycle model WATE++ run file Config File Base Element WATEvspSubelement.int 13

14 14 Drawing WATE++ Compressors in OpenVSP Component Parameters Inport location and Radii Outport Radii Total compressor length IGV length Front frame length Stage Parameters Blade axial length (each stage) Stator axial length (each stage) Spacing length (or % of stage length) Num blades (each stage) Tip Radius Hub radius (or HtoT ratio) Blade Parameters Twist distribution Airfoil shape Taper Etc. OpenVSP Socket for HPC and LPC PROPELLER element for blades FUSELAGE2 element for hub and casing 150Pax HPC 150Pax Booster

15 Issues with the Compressor Elements Issue of how to properly contour the casing Currently placing a FUSELAGE2 cross section at every blade trailing edge Interpolating between the rotor casing radius to get the stator blade tip radius (stators are flush with casing) May want more complex case contouring Tip clearance Added a single variable to the WATE socket which is applied at each stage Could specify tip clearance on a per-stage basis Casing-stator overlap 15

16 A complete separate flow high bypass engine was modeled using OpenVSP sockets added to the required WATE++ elements This OpenVSP model consists of 62 components, either PROPELLER or FUSELAGE2 components, representing the engine components Still to be developed are the combustor, shafts and disks, and true airfoil representations Turbofan Engine Demo 16

17 17 Current Progress Outside Track Propulsion Airframe Integration

18 18 OpenVSP in the PAI Design Process Lower Fidelity Design Codes Define Initial Geometry Inlet, Nozzle, Nacelle Design Codes Higher Order Analyses 3-D Geometry Tool Adds Design DOF Vehicle Sketch Pad Meta-Geometry Higher Fidelity Aero Codes, Structural Analysis Codes, etc Higher Order Analyses CART-3D

19 19 Cowl/Nozzle/Engine Parameters Fore cowl Tan Str1 and 2 Aft Tan Str1 and 2 Lmax Aft Length Rexit Cowl/Nozzle Parms Eng/Nozzle Shape Rmax/Rfan* Boattail* Lmax/Rmax Fore Cowl Tan Str1* Rexit Fore Cowl Tan St2* Area Ratio Aft Tan Str1* Aft Length Aft Tan Str2* Top/Bot Sym Top/Bot Sym Left/Right Sym Left/Right Sym Rmax

20 20 Inlet Parameters Lip Tan Str1 and 2 Diffuser Tan Str1 and 2 L Rhl Rfan Inlet Parms Rfan Rhl/Rfan* Rth/Rhl* Lip Fineness L/Rfan scarf*** Top/Bot Sym Left/Right Sym Inlet Shape Number of Interp Xsecs** Diffuser Tan Str1* Diffuser Tan Str2* Lip Tan Str1* Lip Tan Str2* Top/Bot Sym Left/Right Sym Rth Lip Fineness x (Rhl-Rth)

21 21 Axisymmetric Converging Nozzles: Two types: Bypass nozzle, Core nozzle Bypass Nozzle: Cowl connecting nozzles 3 (outer) or 4 (inner) FUSELAGE2 cross sections Nozzle Parameters Area Ratio Inner Tan Str 3 L/D Inner Tan Str 4 Inport Axial Loc Outer Tan Str 1 Inport Inner R Outer Tan Str 2 Inport Outer R Outer Tan Str 3 Inner Tan Str 1 Outer Tan Str 4 Inner Tan Str 2 By-pass Boattail Core Nozzle: Plug Bypass Nozzle Parms 3 (outer) or 4 (inner) FUSELAGE2 cross sections Core Nozzle Parms Area Ratio Inner Tan Str 1 L/D Inner Tan Str 2 Inport Axial Loc IOuter Tan Str 1 Inport Inner R Outer Tan Str 2 Inport Outer R Core Boattail Plug Length Bypass Nozzle Core Nozzle Plug

22 Wall Points Nacelle Points 22 Example: WATE++ Nacelle Point x-geometry Relation y-geometry Relation 1 0 Rfan 2 Fan Out Location - Fan stage length Rfan 3 -(L/D ratio * Fan Radius) Rth 4 x3-2*(rhi-rth)/5 5 x3-2*(rhi-rth)*2/5 Quadratic fit using distance from throat to 6 x3-2*(rhi-rth)*3/5 Inlet lip leading edge 7 x3-2*(rhi-rth)*4/5 8 x3-2*(rhi-rth) Rhi (=1.2*Rth) 9 x3-2*(rhi-rth) Rhi (=1.2*Rth) Percentage of Point 15 based on lip Airfoil Shape { 0.01, 0.02,0.03,0.06, 0.10,1.0} Fixed Percentage of Point 15 based on lip Airfoil Shape {.1302,.1839,.225,.317,.4071,1.0} 15 (-1.92*(1.0/(Rmax/Rhi)+2.088)*2.0*Rmax Max Nacelle Radius 16 FanfaceToMaxNacelleArea Max Nacelle Radius 17 Byp Nozz Outport Location Byp Nozz Outer Radius 17 Variable diameter Ath Ahit Ahib Ldratio At Ab twall x AbypNozz Lnozzle Description fan diameter Throat Area (Corrected Mass flow) Highlight area of the top Highlight area of the bottom Length of diffuser/dfan Distance from HL to Throat top Distance from HL to Throat bottom Thickness of the wall at max area Distance from Highlight to max area Bypass nozzle area Distance from fan face to bypass nozzle area

23 OpenVSP has the capability to combine two open components into a single mesh using CompGeom or CFD Mesh Components must have coincident beginning and ending cross-sections Multiple open components (>2) cannot currently be combined into a single mesh Either change the way WATE++ draws a fueslage or modify the OpenVSP meshing logic Nacelle Meshing Issue 23

24 24 Model Problem Investigation Illustrate utility and flexibility of parameterized components Demonstrate capability to geometrically model novel and unique advanced concepts Test the limits of OpenVSP and its components Are the provided components sufficient? If not should they be reworked/modified or should new components be added? Test the component parameterizations and the integration relationships Use Cart3D to validate applicability of parameterizations in an analysis environment

25 Model Problem Progress Constructing baseline and advanced concept models in OpenVSP using parameterized components Setting up flow-through analysis on meshed nacelle in Cart3D Using pucks to define boundary conditions at inlet and exit of through-flow nacelle 25

26 Observations from Year 1 OpenVSP Graphics Display Update Speed Currently, the display update speed of OpenVSP with the 62-component engine model is unacceptable This may be partially due to the number and/or complexity of the components that must be modeled, but consensus is that it has more to do with the internal OpenVSP graphics procedures 26

27 Observations from Year 1 (cont d) Need for Improved Component Parameterizations The most significant finding from last year s work is the need for improved component parameterizations within OpenVSP It was decided early on to use the same parameterizations as in WATE++ However, once in OpenVSP, the parts have the parameterization of the OpenVSP components (i.e., of the PROPELLER and FUSELAGE2 elements), and the WATE++ parameterization is lost Solution: create new OpenVSP elements to support the WATE++ parameterization 27

28 Tube Element Notional Views Currently requires two FUSELAGE2 elements Will be useful for embedded inlets, scarfed inlets, non-axisymmetric ducts, etc. 28

29 29 Ginsu Element OpenVSP Depiction Ring Blade Disc The basic element has three components: Casing (outer diameter) ring Rim (inner diameter) disc Strut or blade sections

30 30 Ginsu Element (cont d) One basic element can model most engine flowpath components Omit rim piece to represent a vane row Basic element used as a frame component Omit casing piece and format rim piece to represent a bladed disk

31 Inside Track Year 2 Work Plan Create new tube and Ginsu OpenVSP elements Update OpenVSP sockets to use the new elements Develop combustor, shafts and disks, and true airfoil representations Outside Track Continue work on model problems Investigate meshing issues Introduce additional design and analysis codes SUPIN Calculix 31