NASA Technical Reports Server (NTRS) 20000037781: HyShot-T4 Supersonic Combustion Experiments

32 Pages·1.3 MB·English

by  NASA Technical Reports Server (NTRS)

_S'lt t-, 7/7t_.///'lJ. -'_- :!:_
HyShot-T4Supersonic
Combustion Experiments
Report for NAG- 1-2113
A.Paull, M.Frost and H.Alesi
The Centre for Hypersonics
Dept. of Mechanical Engineering
The University of Queensland, 4072
Australia
TABLE OF CONTENTS
Introduction .................................................................................................................. 3
Flight Test Description .................................................................................................. 3
Model Configuration ................................................................................................... 3
Flight and Experimental Model Relationships ...................................................... 3
General Overview .................................................................................................... 4
Intake ......................................................................................................................... 5
Combustion Chamber ............................................................................................ 6
Thrust Surface ............................................................................................................ 7
Experimental Matrix ..................................................................................................... 9
Results ............................................................................................................................ 9
General Overview .................................................................................................... 9
Fuel Flow Rate ......................................................................................................... 10
Pressure Time History .............................................................................................. 10
Pressure Distance History ...................................................... •................................ 11
0-Degree Angle of Attack ................................................................................. 11
Angle of Attack ................................................................................................... 12
4° Angle of Attack and 4° Skew ....................................................................... 14
Average Combustion Chamber Pressure ........................................................... ]4
Thrust ........................................................................................................................ ]8
Boundary Layer Separation .................................................................................. 20
Summary ..................................................................................................................... 23
References ................................................................................................................. 23
Table 1- Run Summary ............................................................................................. 24
P_
PRELIMINARY REPORT ON THE HYSHOT 5CRAM-lET EXPERIMENTS IN T4
INTRODUCTION
A series of experiments were initiated to investigatethe operation of a two-dimensional, hypersonic,air-
breathing engine (scramjet) inclined at angles of attack to the freestream. The experiments were
undertakentoobtaindata foruseinthe Hyshotflighttestprogram.
ExperimentsontheHyshotscramjetwereundertakenintheT4shock tunnel. Experimentswere madeat a
nominal total enthalpy of 3.0MJkg-1 using a nozzle that produced flows with a Mach number of
approximately 6.5. The conditions produced correspondto flightat Mach7.6 at analtitude rangeof 35.7 -
21.4km. Asummaryof theflowconditions isincludedasTable 1.
The scramjetwastested at 0, plus 2, plus 4, minus 2and minus4degrees angle of attack. Experiments
were alsoundertakenat2and4degreesangleofskew.
FLIGH T TES T DESCRIPTION
The Hyshot flight program will perform a flight test of a configurationrepresenting a two-dimensional,
supersonic combustion ramjet(scramjet) that hasalso beentested inthe T4shock tunnel. The aim of the
Hyshot program isto obtain acorrelation betweenflightbased testing andground based testing inthe 1"4
shocktunnel.
Thescramjetwill beacceleratedto Mach8usingaTerrier-Orionsounding rocket. The sounding rocketwill
reach amaximum altitudeof 350kin. Beforere-entrythe soundingrocket andscramjetwillbemaneuvered
intothe experimentalattitude. Betweenaltitudesof 35kmand23kin gaseoushydrogen will beinjectedinto
thescramjetandpressuremeasurements willberecorded. Aflight MachNo.of7.6witha3-sigmavariation
of 0.2isexpected.
I'_ODEL CONFIGURATION
Flight and Experimental Model Relationships
Aschematicof theflightmodelandtheexperimentalmodelisshownas Figure1. Flightconditionsassume
a Mach7.6 flow. The rangeoffreestream pressuresandtemperatures (P®and T_orespectively) expected
during flightaredeflected byan 18° wedge and areprocessed the shock system, depicted inFigure 1, to
produce a combustion chamber entry temperature of approximately 1100°K and a combustion chamber
entrancepressurewhich rangesbetween22kPaand32kPa. Thecombustionchamberentrypressures and
temperatures (PoandTo)areshowninFigure 1.
Experiments in the T4 shock tunnel used a nozzle with a Mach number of 6.5. To reproduce the
combustion chamber entranceconditions expected duringflight, a 17° compressionwedge wasused, see
Figure 1. Thetotalenthaplyoftheflowwasthesameas inflight.
Page 3
PRELIHINARY REPORT ON THE HYSHOT SCRAM,JET EXPERIHENTS IN T4
Scramjet Schematic (Flight) I
_. Coml::_sion Wedge III
_/ Combustor InnerSurface Th_uslPlale
P_=4.0kPo -0.6kPa J35km-22kin) _-_ ._._
T_=223"K -218"K (35kin -22kin) C_ /
Po=216kPo -32kPo (35kin -22kin)
To=I102"K- 1077"K(35km -22kin)
Scramjet Schematic (Experimental)
Compcesdon wedge
_/ Combuslo¢ Inner Surface l"hrustRole
M,5,._ --..
P.,T. _. I-
-.<_'l.,)x/,l.,I,l,'l.'l,l,'/.'l,I, /.'l,lz I.'1,1, I.'1,1, I.'i,I,/.'lJ
P==_.SkP(] -O.gkPa (35kin -22kin) _- _ _.p'X_'x_,_o1 //
T®=285"K -291°K (35kin -22kml
Po=216kPo -32kPa (35kin-2"2krn)
To= 110"Z"K- 1077"K(35kin -22kin)
FigureI -HyshotScramjetSchematic- relationshipbetweentheflight modelandtheexperimentalmodel.
General Overview
The engineused in the experiments (Figure 2) features an intake, a combustion chamber and a thrust
surface. The intakecompresses the freestream using a 17-degreecompression wedge. Compressed air
fromthe intake entersthecombustion chamberwheregaseoushydrogen isinjectedfromporthole injectors
located downstream of the combustion chamber entrance. Flow exiting the combustion chamber is
expanded over a thrust surface. The experimental modelmounted inthe test section of the T4 tunnel is
shownas Figure3.
Figure2-3dModeloftheHyshotScramjet
Page 4
PRELIMINARY REPORT ON THE HYSHOT SCRAM,JET EXPERIMENTS IN T4
Intake
Theintake is a 17-degreecompression wedge, two intakesidewalls and an extension of the intakecowl
(Figure 4). The compression wedge is lOOmm wide and 305ram long. The leading edge of the
compressionwedge hasbeenbluntedwitha2mm radius. Theintakesidewalls are6ramthick. The leading
edgesof intakesidewalls have a20-degreetaper perpendicularto thedirectionofflow andarebluntedwith
a 2ram radius. The intake has beendesignedso thatwhen operating at between + 4-degree angle of
attack, the flowentering the combustionchamber hasuniformtemperature,velocity and pressure. Thisis
achieved by allowing shocks generated by the leadingedges andthe cowl to spill through agap located
betweenthe trailing edgeof the compression wedge and the entrance to the combustion chamber. This
small gap also bleeds the boundary and entropy layers formed on the compression wedge. Boundary
layersformed onthe sidewalls are bleedout through cutoutslocated onthesidewalls. These cutouts have
also been designed so that the internal contraction ratio is 1.5. This should allow for selfstarting of the
hyshotexperiment. Figure4,displays athreedimensionalrepresentationofthe intakeassembly.
Figure3-Hyshot Scramjet ModelinT4TestSection
Page 5
PRELIMINARY REPDRT ON THE HYSHDT SCRAM,JET EXPERIMENTS IN T4
qP
(p _pression Wedge
Sidewall
Sidewall Cutout
Figure4-3dModeloftheIntakeAssembly
Combustion Chamber
The combustion chamber is formed from an assembly of the cowl, two sidewalls and an inner surface
(Figure 5). The combustionchamber has aconstantcross-sectional area andshape throughout itsentire
length. Thechamber is 300mm long, 75mmwide and9.8ramhigh. Four2mm porthole fuel injectors are
located40ramfromthe leadingedgeofthe innersurface. Theinjectors injectfuel at90degrees tothe flow
withinthe combustion chamber. Cavitieswithin the combustor innersurface link the injectors to fuel line
connection points. A cutawayof thecombustion chamber innersurface (Figure 6)shows the internal fuel
cavitiesand injectors. Pressuretransducersare locatedat 13ramcenters alongthe centerline of the inner
surface. The first transducer is located 90ram downstream from the inner surface leading edge. Two
additionaltransducers, locatedaboveinternalfuellines,measurethefuel pressure.
Poge 5
PRELIMINARY REPORT ON THE HYSHOT -qCRAMJET EXPERIMENTS IN T4
Combustion Chamber Inner Surface
Cowl
Combustion Chamber Sidewall
Figure5-3dModelofCombustionChamberAssembly
Thrust Surface
Thethrustsurface isformedfromathrust plateinclinedat 12degreestothe combustionchamberinner
surface. Thethrust plateis75ramwideand200ramlong. Twosideplatesconnectthethrustplatetothe
cowl. Pressuretransducersare locatedat 13ramcentersalongthecenterlineofthethrustplate. Thefirst
transducerislocated11ramfromthe exitofthe combustionchamber. Thisdistanceis takenalongthe
lengthofthethrustsurface.
Page 7
PRELIMINARY REPORT ON THE HYSHOT SCRAMJET EXPERIMENTS IN T4
Fuel Cavities
Injectors
Taps for Pressure Transducers
Figure 6- 3dCutaway ofCombustion Chamber InnerSurface
Thrust Block/Cove
Thrust Plate
Mount
Cowl
Thruster Sideplate
Figure 7- 3dThruster Assembly
Page 8
PRELIMINARY REPORT ON THE HYSHDT SCRAM,JET EXPERIMENTS IN T4
EXPERIMENTAL MATRIX
Figure 8is anexperimental matrix,whichoutlines theexperiments undertaken. Thedesign conditionare
defined as0-degreeangleofattack. Angleof attackexperimentswereundertakenat2-degrees, 4-degrees,
minus2-degrees andminus4-degrees. Skewexperimentswereconducted at 2-degrees and4-degrees at
0-degree angleof attack. At each angle of attack the equivalenceratio altitude were varied. The typical
equivalence range investigated for each angle of attack is shown in Figure 8. The equivalence ranges
shownaretypicalandvariedslightly ateach altitudetested.
The experimental matrix was repeated for a
number of freestream pressures representing
TestsConducted
altitudes that correspond to expected flight
Altitudes: 35km(Imm}, 28kmJ2mm}, 23km(3mm)
conditions. The compression tube diaphragm
Pitch
thickness was varied to produce the required
freestream pressure. A diaphragm thickness of
1ramwas usedto simulate a nominal altitudeof
35kin, 2mm for nominal altitude of 28km and
3ram for ,a nominal altitude of 23km.
Experiments were also conducted at design
conditions using 4mm diaphragms which
correspondedto anominal altitudeof 21kin.
During the experiments a wedge extension was jConditionsj_ z_j- .... [_Yaw
added to the model to block the small gap
between the model base plate and the
compression wedge. This extension was added
tosimulate thesymmetry oftheflight model. The
wedge was removed after observation showed
that the wedge did not affect the performanceof
the scramjet. Also a wedge obstruction was
placed between the model base plate and the
combustion chamber inner surface to simulate
Figure8- ExperimentalMatrix
the pressure transducer cover on the flight
model. These modifications hadnoeffect inthe
combustion chamber and thrust surface
measurements.
RESUL TS
General Overview
The T4 reflected shock tunnel was used for Hyshotscramjet experiments. Thisfacility is located inthe
Centrefor Hypersonics,atthe Universityof Queensland. The T4facility isafree pistondriven shock tunnel.
The Hyshot scramjet experiments, reported in this document, used the Mach 6.5 contoured nozzle.
Experimentswere conducted atanominalenthalpyof3.0MJkg-1.
Adescription ofthe testsundertaken, includingfreestreamconditions,measuredstagnation pressuresand
shock speedswithinthe shock tube areincludedas Table 1(see appendixA). The freestream conditions,
presented inTable 1, have beencalculated fromthe shock speed,stagnation pressure andcontour of the
nozzle, usingtheESTC(Mclntosh 1968)andNENZF(Lordieta11966)codes.
Page 9
PRELIMINARY REPORT ON THE HYSHOT _qCRAMJET EXPERIMENTS IN T4
Pressuremeasurements wererecorded usingPCB pressuretransducers. Measurements wererecorded at
arateof 250kHzoneachtransducer using a12bitanalogtodigital converter. The datawas reduced using
theUQ program,MONCv4.8.
Fuel Flow Rate
Fuel issupplied tothe injectorsfromtheT4 fuelsystem. The T4fuel system consists ofaLudwich tube, a
fastacting largemassflow ratevalve,interconnectingpipework andassociatedvalving. The Ludwich tube
is of sufficient length to supply fuel, at a steady pressure, to the scramjet model for approximately 30
milliseconds. ThefastactingfuelvalveislocatedbetweentheLudwichtube andthe injectors.
Thefuelsystem wascalibratedbyfillingthe Ludwichtubetoaknownpressurewithgaseous hydrogen.The
fast actingfuel valvewas then activated andafuel pressure(FPm)time history wasrecorded upstream of
theinjectors. Thepressurewithinthe Ludwichtube aftervalveactivationwasalso recorded.Assuming the
fuelflowisisentropicandadiabaticitcanbeshownthatthe massflowrateoffuel is:
x fFPm / °''4
' r'h=k x FPm L'-_-i ,)
Where FR - fillingpressureofthe Ludwichtubeandkistheproportionalityconstant.
By integrating both sides of the above equation with respect to the time that the valve wasopened, and
using the change in Ludwichtube pressureto determinethe mass of the injectedfuel, the proportionality
constant, k, can be determined experimentally. The proportionality constant for the Hyshot scramjet
experimentswasdeterminedto be1.62x108.Theerror inthismeasurementwas + 3%.
Pressure Time History
Figure 9 displays a typical pressure time history for a pressure transducerlocated in the combustion
chamber. The pressure history shownis fortransducer number 15,located 272mmdownstream from the
leadingedgeof thecombustion chamber. Thistransduceris thesecond lasttransducer inthe combustion
chamber. The chart shows the traces for a fuel off shot (6779) and a fuel on shot (6782). These
experiments were conducted at a 0-degree angle of attack and a nominal altitude of 28km. The trace
highlightsthepressurerisethatisassociatedwithcombustion.
Page 10