DOCSLIB.ORG

Validation of Truncation Philosophy for 3-D Scramjet Inlets

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Validation of Truncation Philosophy for 3-D Scramjet Inlets Air Force Research Laboratory Robust Scramjet Program: Validation of Truncation Philosophy for 3-D Scramjet Inlets Trent M. Taylor, Thomas D. Wolf, Ronald R. Springer, and Stephen M. D’Alessio round testing of a medium-scale scramjet engine in semifree- jet mode will require development of a technique for truncat- ing 3-D inlets to provide confidence that the performance and operability of a full-length inlet is accurately represented. Trun- cation is necessary because of the test section size limitations of current hypersonic test facilities. A method was developed by APL, under the Air Force Research Laboratory Robust Scramjet program, to truncate a streamtraced 3-D inlet. Correlations were also developed to relate flow parameters between the full-length and truncated inlets that yield similar perfor- mance and operability. A pair of subscale inlets (baseline and truncated) have been designed and fabricated to be tested at the NASA Glenn Research Center 1- by 1-Foot Supersonic Wind Tunnel to verify this truncation methodology and correlation. This TRuncated INlet Test (TRINT) was concluded in the fourth quarter of 2011; the test covered a range of Mach numbers at various angles of attack and included evaluation of inlet performance during backpressured runs (i.e., an attached operating combustor was simulated). Analysis of the results is still pending, and if acceptable performance and operability similarity were demonstrated in the test, this truncation approach can be used for future Robust Scramjet engine demonstration tests. MOTIVATION Freejet testing of an integrated engine system (i.e., increases. The length of the system can become too engine system is immersed in the supersonic flow) large to fit in the test section, and the blockage area becomes increasingly difficult as the size of the engine of the inlet can prevent the facility from maintaining JOHNS HOPKINS APL TECHNICAL DIGEST, VOLUME 32, NUMBER 1 (2013) 395 T. M. TAYLOR ET AL. the desired operating condition. If the inlet can be truncated, M 0 Full-scale inlet (2-D) the total length of the test arti- M1 A0A = 0° cle can be reduced, which, in M2 turn, reduces blockage in the M wind tunnel. However, if the 3 flow properties (pressure, tem- perature, velocity, etc.) and inlet performance are significantly impacted by this truncation, A0A = ow-turning angle then the test data for the engine Truncated inlet (2-D) M1 are no longer valid. A carefully M2 designed truncation methodol- M3 ogy can minimize the differences so that integrated engine perfor- mance can be measured. Trun- cating an inlet can be a relatively straightforward process for a 2-D Figure 1. Truncating a 2-D inlet. inlet, as seen in Fig. 1. The flow properties downstream of the first ramp on the 2-D inlet within the propulsion system. On a 3-D inlet, flow is can be easily found with computational fluid dynamics being compressed in all directions and there is no mean- (CFD) or experimentation. The first ramp can then be ingful plane to remove as there is in a 2-D inlet. No removed, and its flow turning can be replicated by low- known program to date has examined methods for trun- ering the inlet angle of attack (AOA). The wind tunnel cating a 3-D inlet and conducted tests to determine the must be set to the appropriate flow conditions, i.e., sta- validity of the approach. tion M1 versus M0. The isolator is the constant area sec- tion downstream of the compression ramps. This is the portion of the inlet where the pressure rise required for DEVELOPMENT OF 3-D INLET TRUNCATION combustion is contained and one of the places where METHODOLOGY flow properties will be examined. The current designs For the 3-D streamtraced inlets considered in this being considered for use in the Robust Scramjet program truncation investigation, the Busemann flow field (see all use inward-turning 3-D inlets. Inward-turning inlets Fig. 2) was selected as the parent flow. The baseline inlet are designed to compress the flow in a 3-D manner as was derived by tracing streamlines through the top por- opposed to planar compression of pure ramp inlets. The tion of this flow where inlet surfaces are defined as the advantage of the inward-turning engine concepts is a streamlines first turn from their original axial direction. lower wetted surface area per unit mass flow processed The truncated inlet is made by removing portions of the by the engine. This feature inherently leads to lighter baseline inlet at a higher flow-turning angle. This Buse- structures, lower heat loads, and fewer frictional losses mann flow field is characterized by internally contracting, Mach contours Conical shock Isentropic compression Flow angle contours Figure 2. Busemann inlet. (Reproduced from Ref. 4 with permission of the American Institute of Aeronautics and Astronautics.) 396 JOHNS HOPKINS APL TECHNICAL DIGEST, VOLUME 32, NUMBER 1 (2013) AFRL ROBUST SCRAMJET PROGRAM: SCRAMJET INLET TRUNCATION conically symmetric flow that uses isentropic compres- With the streamtubes defined, the 3-D streamlines sion and terminates in a conical shock that realigns the were read into a grid-generation program as databases. flow to the axial direction, as shown in Fig. 2. The Buse- These were used to create a surface mesh and then a mann inlet has naturally high on-design performance 3-D mesh. This method was tested and verified by solv- because the forward compression occurs isentropically. ing the 3-D mesh in a CFD code with a calorically per- The principal disadvantage of the Busemann inlet from fect and inviscid gas, which are the assumptions of the a practical point of view is that its internal contraction Taylor–Maccoll equations. Both an inlet with a circular significantly exceeds the Kantrowitz1 starting constraint inflow and circular outflow profile and an inlet with a for inlets of interest. In supersonic inlets, a normal shock square inflow and square outflow profile were solved in (or series of high-strength shocks) can set up in the for- the CFD code. The total pressure losses and inlet exit ward part of the inlet and will deflect much of the mass Mach numbers closely matched the values predicted flow from flowing down the inlet. An inlet with these by the Taylor–Maccoll equations and conical shock high-strength shocks and low mass flow rates is labeled equations. Total pressure is defined as the pressure that as unstarted. The Kantrowitz starting constraint defines results from slowing the flow to zero velocity in an isen- an area ratio of the inlet that is necessary to have the tropic (adiabatic and reversible) manner. Shock waves shock system pass through the inlet and allow the mass and viscous losses will reduce the total pressure of the to flow down the inlet, i.e., to start the inlet. Streamline flow. A series of cross-flow slices was visualized from tracing within the Busemann inlet provides the oppor- inflow to exit of the inlet, and a conical shock shape tunity to leverage the high performance of Busemann was observed in both the inlet with a circular profile and design while avoiding the high internal contraction. the inset with a square profile. The parent Busemann inlet flow is generated from a It was also of interest to the Robust Scramjet pro- solution of the Taylor–Maccoll2 equations. In the pres - gram to examine inlets that undergo shape transition ent work, a method similar to that shown by VanWie from the inflow to exit of the inlet—namely, those inlets and Molder3 was used to solve the equations and derive whose cross-section transitions from a square shape to a the Busemann flow field. The process starts by assum- circular shape. Various methods were examined for this ing a Mach number and total pressure loss at the exit of shape transition and its impact on inlet performance. the inlet. The conical shock strength can then be deter- The main focus of this current work is to examine trun- mined, and the flow field is then integrated backward cation methods, so further details on the shape transi- through the inlet using the Taylor–Maccoll equations tion study can be found in Ref. 4. The optimal method until the flow becomes aligned with the freestream. A found is in this study was used to generate the baseline Fortran program was written for this work to numeri- inlet geometry used in this truncation study. cally integrate the equations using a Runge–Kutta As the flow is compressed in the forward section of method to find the inlet inflow conditions. The inlet the inlet, the amount of flow-turning (deflection from exit conditions were then iterated using a bracketing the axial direction) increases. The truncation method method to find the parent flow field that had the desired developed for the Robust Scramjet program uses the inflow Mach number and contraction ratio (ratio of the streamlines of the baseline inlet and truncates these entrance area to exit area). lines at an increased turning angle such that the inlet Having defined the axisymmetric parent flow field, profile is changed but the geometry downstream of the a locus of points defining the cross-sectional perimeter truncation remains the same. The method starts with of the desired inflow shape was placed in the freestream the streamlines of the baseline inlet and then removes of a 3-D representation of the axisymmetric flow field. the leading portions of the inlet up to a surface that is Then, streamlines were traced through these points at a larger flow-turning angle. Thus, the truncated inlet using a Fortran program. The resulting streamlines surfaces are kept as a subset of the baseline surfaces.
Load more

Recommended publications
  • The SKYLON Spaceplane
    The SKYLON Spaceplane Borg K.⇤ and Matula E.⇤ University of Colorado, Boulder, CO, 80309, USA This report outlines the major technical aspects of the SKYLON spaceplane as a final project for the ASEN 5053 class. The SKYLON spaceplane is designed as a single stage to orbit vehicle capable of lifting 15 mT to LEO from a 5.5 km runway and returning to land at the same location. It is powered by a unique engine design that combines an air- breathing and rocket mode into a single engine. This is achieved through the use of a novel lightweight heat exchanger that has been demonstrated on a reduced scale. The program has received funding from the UK government and ESA to build a full scale prototype of the engine as it’s next step. The project is technically feasible but will need to overcome some manufacturing issues and high start-up costs. This report is not intended for publication or commercial use. Nomenclature SSTO Single Stage To Orbit REL Reaction Engines Ltd UK United Kingdom LEO Low Earth Orbit SABRE Synergetic Air-Breathing Rocket Engine SOMA SKYLON Orbital Maneuvering Assembly HOTOL Horizontal Take-O↵and Landing NASP National Aerospace Program GT OW Gross Take-O↵Weight MECO Main Engine Cut-O↵ LACE Liquid Air Cooled Engine RCS Reaction Control System MLI Multi-Layer Insulation mT Tonne I. Introduction The SKYLON spaceplane is a single stage to orbit concept vehicle being developed by Reaction Engines Ltd in the United Kingdom. It is designed to take o↵and land on a runway delivering 15 mT of payload into LEO, in the current D-1 configuration.
    [Show full text]
  • Modelling a Hypersonic Single Expansion Ramp Nozzle of a Hypersonic Aircraft Through Parametric Studies
    energies Article Modelling a Hypersonic Single Expansion Ramp Nozzle of a Hypersonic Aircraft through Parametric Studies Andrew Ridgway, Ashish Alex Sam * and Apostolos Pesyridis College of Engineering, Design and Physical Sciences, Brunel University London, London UB8 3PH, UK; [email protected] (A.R.); [email protected] (A.P.) * Correspondence: [email protected]; Tel.: +44-1895-267-901 Received: 26 September 2018; Accepted: 7 December 2018; Published: 10 December 2018 Abstract: This paper aims to contribute to developing a potential combined cycle air-breathing engine integrated into an aircraft design, capable of performing flight profiles on a commercial scale. This study specifically focuses on the single expansion ramp nozzle (SERN) and aircraft-engine integration with an emphasis on the combined cycle engine integration into the conceptual aircraft design. A parametric study using computational fluid dynamics (CFD) have been employed to analyze the sensitivity of the SERN’s performance parameters with changing geometry and operating conditions. The SERN adapted to the different operating conditions and was able to retain its performance throughout the altitude simulated. The expansion ramp shape, angle, exit area, and cowl shape influenced the thrust substantially. The internal nozzle expansion and expansion ramp had a significant effect on the lift and moment performance. An optimized SERN was assembled into a scramjet and was subject to various nozzle inflow conditions, to which combustion flow from twin strut injectors produced the best thrust performance. Side fence studies observed longer and diverging side fences to produce extra thrust compared to small and straight fences. Keywords: scramjet; single expansion ramp nozzle; hypersonic aircraft; combined cycle engines 1.
    [Show full text]
  • Flight Data Analysis of the HYSHOT Flight #2 Scramjet
    13th AIAA/CIRA International Space Planes and Hypersonic Systems and Technologies Conference Flight Data Analysis of HyShot 2 Neal E. Hass*, Michael K. Smart+ NASA Langley Research Center, Hampton, Virginia Allan Paull! University of Queensland, Brisbane, Australia Abstract The development of scramjet propulsion for alternative launch and payload delivery capabilities has comprised largely of ground experiments for the last 40 years. With the goal of validating the use of short duration ground test facilities, the University of Queensland, supported by a large international contingency, devised a ballistic re-entry vehicle experiment called HyShot to achieve supersonic combustion in flight above Mach 7.5. It consisted of a double wedge intake and two back-to-back constant area combustors; one supplied with hydrogen fuel at an equivalence ratio of 0.33 and the other un-fueled. Following a first launch failure on October 30th 2001, the University of Queensland conducted a successful second launch on July 30th, 2002. Post-flight data analysis of the second launch confirmed the presence of supersonic combustion during the approximately 3 second test window at altitudes between 35 and 29 km. Reasonable correlation between flight and some pre-flight shock tunnel tests was observed. Nomenclature f aerodynamic factor h altitude M Mach number P pressure q dynamic pressure s seconds T temperature V velocity w mass flow X axial coordinate Y lateral coordinate Z normal coordinate α angle-of-attack ηc combustion efficiency γ ratio of specific heats φ equivelance ratio ω angular velocity about longitudinal body axis ζ angular velocity of longitudinal axis about velocity vector * Aerospace Engineer, Hypersonic Airbreathing Propulsion Branch + Research Scientist, Hypersonic Airbreathing Propulsion Branch ! Professor, Mechanical Engineering Department 1 Subscripts: 0 freestream c combustor entrance w wedge t2 Pitot Introduction The theoretical performance advantage of scramjets over rockets in hypersonic flight has been well known since the 1950’s.
    [Show full text]
  • Ciam/Nasa Mach 6.5 Scramjet Flight and Ground Test
    AIAA-99-4848 CIAM/NASA MACH 6.5 SCRAMJET FLIGHT AND GROUND TEST R. T. Voland* and A. H. Auslender** NASA Langley Research Center Hampton, VA M. K. Smart Lockheed Martin Engineering Sciences Hampton, VA A.S. Roudakovà, V.L. Semenov¤, and V. Kopchenov¤ Central Institute of Aviation Motors Moscow, Russia ABSTRACT NOMENCLATURE The Russian Central Institute of Aviation Motors (CIAM) performed a flight test of a CIAM-designed, C-16V/K Ð CIAM scramjet engine ground test facility, hydrogen-cooled/fueled dual-mode scramjet engine located in Tureavo, Russia (Figure 10) over a Mach number range of approximately 3.5 to 6.4 CIAM Ð Central Institute of Aviation Motors, Moscow, on February 12, 1998, at the Sary Shagan test range in Russia Kazakhstan. This rocket-boosted, captive-carry test of CO2 Ð Carbon dioxide the axisymmetric engine reached the highest Mach Cp Ð Pressure Coefficient number of any scramjet engine flight test to date. The H Ð Altitude (km, m, or ft) flight test and the accompanying ground test program, H2 Ð Hydrogen conducted in a CIAM test facility near Moscow, were H2O Ð Water performed under a NASA contract administered by the He Ð Helium Dryden Flight Research Center with technical HFL Ð Hypersonic Flying Laboratory assistance from the Langley Research Center. Analysis HRE Ð Hypersonic Research Engine of the flight and ground data by both CIAM and NASA HRE AIM Ð Hypersonic Research Engine, resulted in the following preliminary conclusions. An Aerothermodynamic Integration Model unexpected control sensor reading caused non-optimal Hyper-X Ð NASA airframe integrated scramjet- fueling of the engine, and flowpath modifications added powered vehicle flight test program to the engine inlet during manufacture caused markedly ht Ð Total enthalpy (MJ/kg or Btu/lbm) reduced inlet performance.
    [Show full text]
  • Chemical Kinetics of SCRAMJET Propulsion by Rodger Joseph Biasca Master of Science Aeronautics and Astronautics at the Massachus
    Chemical Kinetics of SCRAMJET Propulsion by Rodger Joseph Biasca S.B. Aeronautics and Astronautics, Massachusetts Institute of Technology, 1987 SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Master of Science in Aeronautics and Astronautics at the Massachusetts Institute of Technology July 1988 ©1988, Rodger J. Biasca The author hereby grants to MIT and the Charles Stark Draper Laboratory, Inc. permission to reproduce and distribute copies of this thesis document in whole or in part. Signature of Author Department of Aeronautics and Astronautics July 1988 Certified by Professor Jean F. Louis, Co- Thesis Supervisor Department of Aeronautics and Astronautics Professor Manuel Martinez-Sanchez, Co- Thesis Supervisor pepartment of Aeronautics and Astronautics nr Phillin T). Hattis, Technical Supervisor s Stark Draper Laboratory Accepted by xtew,Ex3.*sh \. Professor Harold Y. Wachman,Chairman Department Graduate Committee MAOHUSET1S r1nTSrn OF TEO LOGY TH DRWN SEP 07 1988 A MVrN UU. fl~ u<;HZSR3ES~!'-~' Chemical Kinetics of SCRAMJET Propulsion by Rodger Joseph Biasca Submitted to the Department of Aeronautics and Astronautics in partial fulfillment of the requirements for the degree of Master of Science in Aeronautics and Astronautics Recent interest in hypersonics has focused on the development of a single stage to orbit vehicle propelled by hydrogen fueled SCRAMJETs. Necessary for the design of such a vehicle is a thorough understanding of the chemical kinetic mechanism of hydrogen-air combustion and the possible effect this mechanism may have on the performance of the SCRAMJET propulsion system. This thesis investigates possible operational limits placed on a SCRAMJET powered vehicle by the chemical kinetics of the combustion mechanism and estimates the performance losses associated with chemical kinetic effects.
    [Show full text]
  • EMISSION CALCULATIONS for a SCRAMJET POWERED HYPERSONIC TRANS PORT by Erwin A
    NASA TECHNICAL NASA TM X-71464 MEMORANDUM (NASA-TM-X-71464) EMISSION CALCULATIONS N74- 1244 FOR A'SCRANJET POWERED HYPERSONIC TRANSPORT (NASA) 32 p HC $3.75 CSCL 21E Unclas G3/28 2277 1 Cc EMISSION CALCULATIONS FOR A SCRAMJET POWERED HYPERSONIC TRANS PORT by Erwin A. Lezberg Lewis Research Center Cleveland, Ohio 44135 November, 1973 EMISSION CALCULATIONS FOR A SCRAMJET POWERED HYPERSONIC TRANSPORT by Erwin A. Lezberg Lewis Research Center ABSTRACT Calculations of exhaust emissions from a scramjet powered hy- personic transport burning hydrogen fuel have been performed over a range of Mach numbers of 5 to 12 to provide input data for wake mixing calculations and forecasts of future levels of pollutants in the strato- sphere. The calculations were performed utilizing a one-dimensional chem- ical kinetics computer program for the combustor and exhaust nozzle of a fixed geometry dual-mode scramjet engine. Inlet conditions to the combustor and engine size was based on a vehicle of 2.27x10 5 kg (500 000 lb) gross take of weight with engines sized for Mach 8 cruise. Nitric oxide emissions were very high for stoichiometric engine operation but for Mach 6 cruise at reduced equivalence ratio are in the range predicted for an advanced supersonic transport. Combustor de- signs which utilize fuel staging and rapid expansion to minimize resi- dence time at high combustion temperatures were found to be effective in preventing nitric oxide formation from reaching equilibrium concen- trations. INTRODUCTION Calculations of exhaust emissions from a scramjet powered hyper- sonic transport burning hydrogen fuel have been performed over a range of Mach numbers to provide input data for wake mixing calculations and forecasts of future levels of pollutants in the stratosphere.
    [Show full text]
  • Supersonic Combustion in Air-Breathing Propulsion Systems for Hypersonic Flight
    FL50CH23_Urzay ARI 22 November 2017 21:18 Annual Review of Fluid Mechanics Supersonic Combustion in Air-Breathing Propulsion Systems for Hypersonic Flight Javier Urzay Center for Turbulence Research, Stanford University, Stanford, California 94305-3024; email: [email protected] Annu. Rev. Fluid Mech. 2018. 50:593–627 Keywords The Annual Review of Fluid Mechanics is online at hypersonics, compressible flows, turbulent combustion, scramjets, fluid.annualreviews.org high-speed chemical propulsion, sound barrier https://doi.org/10.1146/annurev-fluid-122316- 045217 Abstract Copyright c 2018 by Annual Reviews. Annu. Rev. Fluid Mech. 2018.50:593-627. Downloaded from www.annualreviews.org Great efforts have been dedicated during the last decades to the research and All rights reserved development of hypersonic aircrafts that can fly at several times the speed of sound. These aerospace vehicles have revolutionary applications in national security as advanced hypersonic weapons, in space exploration as reusable ANNUAL stages for access to low Earth orbit, and in commercial aviation as fast long- REVIEWS Further Access provided by Stanford University - Main Campus Robert Crown Law Library on 01/05/18. For personal use only. Click here to view this article's range methods for air transportation of passengers around the globe. This online features: review addresses the topic of supersonic combustion, which represents the • Download figures as PPT slides • Navigate linked references central physical process that enables scramjet hypersonic propulsion systems • Download citations • Explore related articles to accelerate aircrafts to ultra-high speeds. The description focuses on recent • Search keywords experimental flights and ground-based research programs and highlights associated fundamental flow physics, subgrid-scale model development, and full-system numerical simulations.
    [Show full text]
  • A Parametric Analysis on the Performance of Ideal Scramjets Dan Londrico Cleveland State University
    A Parametric Analysis on the Performance of Ideal Scramjets Dan Londrico Cleveland State University Abstract and Background Results Supersonic combustion ramjets, known as The plots show specific thrust, fuel-air ratio, and thrust scramjets, are useful for applications where specific fuel consumption for the three combustor hypersonic flight is desired. Main areas of materials, and fuel-air ratio for the four fuels. research include the use of alternative fuels to reduce system weight and increase performance, and suitable combustor materials to allow for the high temperatures occurring in scramjets, and improve performance. While the research is promising, physical testing in scramjet engines can be expensive. Numerical models offer a good alternative to physical testing, and can be used to analyze trends, and to help direct physical models. The purpose of this research is to analyze the performance of a scramjet numerically using an ideal, one-dimensional thermodynamic model. Methods Conclusion • An ideal system was setup for the analysis • The data from this analysis shows: using these assumptions: • the three alternative fuels used can produce a lower • Isentropic diffuser and exhaust fuel air ratio than JP-7. • Combustion treated as constant heat • increasing the maximum allowable temperature of the addition process combustor increases thrust output, but also increases • Combustion occurs under constant Mach fuel consumption. number • Inlet and outlet pressures are equal • Calorically perfect air as operating fluid Future Work • Combustor materials were varied, and were modelled using their maximum allowable • Future work on this includes: temperature (T): • Performing the analysis using combustion conditions • Inconel, T = 1700K other than constant Mach number, such as constant • C-SiC, T = 1900K velocity, area, or pressure.
    [Show full text]
  • Supersonic Combustion Ramjet: Analysis on Fuel Options
    SUPERSONIC COMBUSTION RAMJET: ANALYSIS ON FUEL OPTIONS by Stephanie W. Barone A thesis submitted to the faculty of The University of Mississippi in partial fulfillment of the requirements of the Sally McDonnell Barksdale Honors College. Oxford May 2004 Approved by ___________________________________ Advisor: Dr. Jeffrey Roux ___________________________________ Reader: Dr. Erik Hurlen ___________________________________ Reader: Dr. John O’Haver 1 © 2016 STEPHANIE BARONE ALL RIGHTS RESERVED 2 ABSTRACT STEPHANIE BARONE: Supersonic Combustion Ramjet: Analysis on Fuel Options This report focuses on different fuel options available to use for scramjet engines. The advantages and disadvantages of JP-7, JP-8, and hydrogen fuels are covered, also the effectiveness and requirements for each fuel are discussed. The recent history of the scramjet engine is included as well as its advantages and disadvantages. An explanation of what each fuel option encompasses and engineering analysis for each fuel are shown. The equations presented for the parametric analysis are shown as functions of the freestream Mach number, with the combustion Mach number as a parameter. The results can be seen for the theoretical possibilities of the scramjet engine and the most likely operating situations. Hydrogen has the highest lower heating value which makes it very appealing to use as a fuel, but it is not very dense so more volume of it is needed to create enough energy. The hydrocarbon fuels, JP-7 and JP-8, have half the value of hydrogen for the lower heating value
    [Show full text]
  • Scramjet Inlets
    Scramjet Inlets Professor Michael K. Smart Chair of Hypersonic Propulsion Centre for Hypersonics The University of Queensland Brisbane 4072 AUSTRALIA [email protected] ABSTRACT The supersonic combustion ramjet, or scramjet, is the engine cycle most suitable for sustained hypersonic flight in the atmosphere. This article describes some challenges in the design of the inlet or intake of these hypersonic air-breathing engines. Scramjet inlets are a critical component and their design has important effects on the overall performance of the engine. The role of the inlet is first described, followed by a description of inlet types and some past examples. Recommendations on the level of compression needed in scramjets are then made, followed by a design example of a three-dimensional scramjet inlet for use in an access-to-space system that must operate between Mach 6 and 12. NOMENCLATURE A area (m2) x axial distance (m) Cf skin friction coefficient φ equivalence ratio D diameter (m); Drag (N) ϑ constant in mixing curve fst stoichiometric ratio ηc combustion efficiency F stream thrust (N) ηKE kinetic energy efficiency Fadd additive drag (N) ηKE_AD adiabatic kinetic energy efficiency Fun uninstalled thrust (N) ηo overall scramjet efficiency h enthalpy (289K basis) (J/kg) ηn nozzle efficiency h heat of combustion (J/kg of fuel) pr H total enthalpy (298K basis) (J/kg) t Subscript L length (m) c cowl m mass capture ratio c comb combustor m& mass flow rate (kg/s) f fuel M Mach number in inflow P pressure (Pa) out outflow Q heat loss (kJ) q dynamic pressure (Pa) isol isolator T temperature (K); thrust (N) n,N nozzle u,V velocity (m/s) SEP separation RTO-EN-AVT-185 9 - 1 Scramjet Inlets 1.0 INTRODUCTION The desire for hypersonic flight within the atmosphere has motivated multiple generations of aerodynamicists, scientists and engineers.
    [Show full text]
  • Conceptual Study of Rocket-Scramjet Hybrid Engines
    NASA TECHNICAL NOTE 00- N m I n z c 4 r/l 4 z CONCEPTUALSTUDY OF ROCKET-SCRAMJET HYBRID ENGINES IN A LIFTING REUSABLE SECONDSTAGE by Andrzej Dobrowolski andJohn L. Allen Lewis Research Center Cleueland,Ohio NATIONALAERONAUTICS AND SPACE ADMINISTRATION WASHINGTON,D. C. MAY 1969 TECH LIBRARY KAFB, NM CONCEPTUAL STUDY OF ROCKET-SCRAMJET HYBRID ENGINES IN A LIFTING REUSABLE SECOND STAGE By Andrzej Dobrowolski and John L. Allen Lewis Research Center Cleveland, Ohio NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by the Clearinghouse for Federal Scientific and Technical Information Springfield,Virginia 22151 - CFSTI price $3.00 ABSTRACT A simplified analysis of a prismatic-delta configuration flying a near minimum fuel consumption path from staging to orbit showed relative advantages for air-augmented propulsion systems. The trajectory had a constant product of pressure and Mach num- ber during powered flight which extended to speeds slightly greater than orbital so that a zoom maneuver could be used to obtain final orbital altitude. For staging at Mach 10, the estimated payload fraction (payload to staging weight) for the best air-augmented case (3:l ratio of air to rocket flow) was 1; times better than that using pure rocket power and 7; times better than that using pure scramjet power. ii 111 - CONCEPTUAL STUDY OF ROCKET-SCRAMJET HYBRID ENGINES IN A LIFTING REUSABLE SECOND STAGE by Andrzej Dobrowolski and John L. Allen Lewis Research Center SUMMARY The lifting second stage of a reusable orbital booster is analyzed employing a highly simplified approach so that major problems, trade-offs, and potential can be identified.
    [Show full text]
  • Free-Jet Testing of a REST Scramjet at Off-Design Conditions Michael K Smart* and Edward G
    Free-jet Testing of a REST Scramjet at Off-Design Conditions Michael K Smart* and Edward G. Ruf# NASA Langley Research Center Hampton Virginia, 23681 Scramjet flowpaths employing elliptical combustors have the potential to improve structural efficiency and performance relative to those using planar geometries. NASA Langley has developed a scramjet flowpath integrated into a lifting body vehicle, while transitioning from a rectangular capture area to both an elliptical throat and combustor. This Rectangular-to-Elliptical Shape Transition (REST) scramjet, has a design point of Mach 7.1, and is intended to operate with fixed-geometry between Mach 4.5 and 8.0. This paper describes initial free-jet testing of the heat-sink REST scramjet engine model at conditions simulating Mach 5.3 flight. Combustion of gaseous hydrogen fuel at equivalence ratios between 0.5 and 1.5 generated robust performance after ignition with a silane-hydrogen pilot. Facility- model interactions were experienced for fuel equivalence ratios above 1.1, yet despite this, the flowpath was not unstarted by fuel addition at the Mach 5.3 test condition. Combustion tests at reduced stagnation enthalpy indicated that the engine self-started following termination of the fuel injection. Engine data is presented for the largest fuel equivalence ratio tested without facility interaction. These results indicate that this class of three-dimensional scramjet engine operates successfully at off-design conditions. Nomenclature I vitiated heater O2 replenishment factor, ratio of the actual mass flow rate of O2 to that required to replace that consumed H enthalpy M Mach number MW molecular weight t time p pressure T temperature φ fuel equivalence ratio γ ratio of specific heats Subscripts 0 flight 1 wind tunnel freestream or inlet entrance st stagnation *Research Scientist; presently Associate Professor, Division of Mechanical Engineering, University of Queensland.
    [Show full text]