SR-71 Inlet Design Issues And Solutions Dealing With Behaviorally Challenged Supersonic Flow Systems

Transcription

1 SR-71 Inlet Design Issues And Solutions Dealing With Behaviorally Challenged Supersonic Flow Systems 3/4/14 Tom Anderson 1

2 A-12, SR-71 Inlet Designers Dave Campbell SR-71 Inlet Designer Propulsion Boss Ben Rich SR-71 Vehicle and Inlet Preliminary Design Propulsion Boss ADP President 2

3 SR-71 Inlet Document 3

4 SR-71 Nacelle Station 0 Station 2 Station 8 Station 9 4

5 Inlet Needed To Capture Ram Pressure Vehicle Velocity Mach Number Pram Pambient Pram-Pambient Pambient Car 70 miles per 0.1 Less than 1.01 Less than.01 hour Airliner 530 miles per hour Fighter 1300 miles per Max Speed hour SR miles per hour A Figure Of Merit For Inlet Performance Is Recovery. Recovery Is The Amount Of Ram Pressure That Is Recovered From The Inlet Compression Process. Recovery = P t2 /P t0 5

6 Inlet Compression Regions Normal Shock A c Oblique Shocks A t Supersonic Diffuser Subsonic Diffuser 6

7 Inlet Configuration Definitions Spike Design Position Cowl Mice Struts Spike Translated Position Fixed Centerbody 7

8 Cowl Pressure Ratio ADP Inlet Cowl Pressure Distribution Normal Shock 4 0 Normal Shock A c Oblique Shocks A t Supersonic Diffuser Subsonic Diffuser 8

9 Ptns/Pto Mach Number Flow Rate/Area ADP Supersonic Compression Ends With Normal Shock Sonic; M=1.0 Normal Shock A c Oblique Shocks A t Supersonic Diffuser Subsonic Diffuser Mach Number 9

10 Supersonic Compression Done Through Compression And Shock Waves 10

11 Basic Law Of Physics Continuity Everything That Enters The Inlet Must Leave Or Be Stored. The Inlet Does Not Act Like A Balloon And Will Not Store Air. Therefore Flow In Must Equal Flow Out. W in =W out = W engine + W bleed + W bypass + W leak Flow In Is Approximately 200 lbs/sec. Therefore Events Happen VERY Rapidly. 11

12 The Problem M o >1.0 M 2 <1.0 Subsonic Air Supersonic Air Skier Is Working Hard Skier Is Blind 12

13 Comparison Of Mo=3.2 Started And Unstarted Performance Inlet Started Recovery 80% Mass Flow 80% Oblique Shocks Normal Shock Oblique Shocks Normal Shock Inlet Unstarted Recovery 20% Mass Flow 20% 13

14 Inlet Flow Schlierens Show Started And Unstarted Operation Inlet Started Inlet Unstarted Ram Recovery = 0.8 Mass Flow Ratio = 0.8 Ram Recovery = 0.2 Mass Flow Ratio =

15 SR-71 Inlet Orientation Facing Into The Wind At Cruise 15

16 Nacelle Centerlines Engine Centerline Dd Inlet Centerline Inlet Cant Dd (Downward) Dd (Inboard) Preliminary 6.5 deg. 0 deg. Final 5.6 deg. 3.2 deg. 16

17 Forward Bypass Matches Inlet And Exit Airflow 17

18 Inlet Automatic Control System 18

19 Variable Geometry Is Required Mach Numbers Below Cruise Require Increased Throat Area. Internal Flow Areas Must Grow In Order To Restart The Inlet From An Unstarted Condition. Therefore Variable Area Internal Geometries Are Required. This is Accomplished On The SR-71 By Spike Translation. 19

20 Inlet Geometry And Area Distribution 80 20

21 Spike Translation Varies Inlet Area Distribution 21

22 Supersonic Diffuser Flow Field 22

23 SR-71 Inlet Bleed Regions 23

24 Cowl (Shock Trap) Bleed Flows To Nozzle 24

25 Centerbody (Porous) Bleed Flows Overboard Support Strut Spike Bleed Exit Louvers (4 Locations) Spike Bleed Exit Louver View Looking AFT Support Strut Spike Bleed (Slotted Surface) Engine Face Side View 25

26 Aft Bypass Flows to Nozzle 26

27 Inlet Geometric Features 27

28 Inlet Diffuser Photos 28

29 Nacelle Leakage Test Rig 29

30 Backup 30

31 Inlet Wind Tunnel Model 31

32 Inlet Airflow Paths 32

33 Inlet Airflow Paths 33

34 Inlet Airflows 34

35 Nacelle Thrust Distribution 35

36 Inlet Pressure Recovery 36

37 Mixed Compression Inlet Characteristics 37

38 Inlet Restart Cycle 38