Presentation on theme: "Instructor: Dr. David R. Greatrix Dept. of Aerospace Engineering"— Presentation transcript:
1 Instructor: Dr. David R. Greatrix Dept. of Aerospace Engineering AE 8129 Rocket PropulsionInstructor: Dr. David R. GreatrixDept. of Aerospace EngineeringRyerson UniversityPhone: ext. 6432Office: ENG 145Counselling hours: posted
2 Additonal Logistics Lecture in ENG LG12, Wed., 9 am – noon Run first part of class from 9:10 am – 10:30 pm, break for half-hour, second part from 11:00 am – noonTutorial (sample problems) incorporated into lectures; counselling hours flexible, my office (ENG 145), if I’m available
3 Logistics (cont’d) Evaluation: 1 Indiv. Proj. Report 25% Oct. 26 (9:10 – 10:00 am)1 Term Test, 50 min. 25%Univ. will sched. in Dec Final Exam, 3 hr %No official course textbook; recommended books are useful for project and filling in gaps in understandingTests are open lecture notes + practice problem/soln. set + regular calculator
4 Logistics (cont’d)Project may involve computer programming and/or spreadsheet analysis, at your discretionZero marks for late project submission
5 Outline of Course: Introduction Solid-Propellant Rocket Motors Liquid-Propellant Rocket EnginesHybrid Rocket EnginesAir-Breathing Rocket EnginesNon-Chemical Space Propulsion Systems
7 Introduction to Rocket Propulsion One associates rocket propulsion with space flight, but applications range from lower atmosphere to outer spaceEmphasis in this course on chemical systems, employing combustion as the means for heat generation; later, will look at less conventional non-chemical approachesThrust produced by exhausting a hot high-speed gas (conventional approach)
8 Mission RequirementsRange of applications for rocket-based systems is considerable, from low end (e.g., pilot ejection seat) to high end (e.g., heavy space launch vehicle)Let’s consider a simpler example, where the flight dynamics equations are more readily calculated: vertical ascent by a rocket vehicle
9 Schematic diagram of single-stage rocket vehicle at sea level launch, quadrant elevation angle o = 90.
23 Area-Mach Number relation: Exit pressure:Thrust:
24 Flow characteristics in convergent/divergent nozzle as chamber pressure is progressively increased relative to constant outside air pressure. Case(1): subsonic flow throughout. Case (2): flow has become choked, withflow ahead of upstream-facing standing normal shock S2 beingsupersonic, and subsonic downstream (overexpanded nozzle). Case (3):standing normal shock S3, with bigger pressure increase across it thanS2, is positioned very near to the nozzle exit plane (overexpandednozzle). Inviscid flow assumed.
25 Flow characteristics in convergent/divergent nozzle as chamber pressure is progressively increased relative to constant outside air pressure. Case(4): supersonic flow throughout internal nozzle region; upstream-facingoblique shock S4 with supersonic flow upstream and downstream tobring pressure up towards ambient level (overexpanded nozzle). Case(5): flow has reached design point, exit-plane exhaust at ambient airpressure. Case (6): exit-plane exhaust pressure now exceeds outside airpressure, thus producing an upstream-facing Prandtl-Meyer rarefaction(expansion) wave to bring pressure down (underexpanded nozzle).2Inviscid flow assumed.
26 Nominal exhaust flow patterns for an overexpanded supersonic nozzle (upper diagram; Case 4 of previous slide) and an underexpanded supersonicnozzle (lower diagram; Case 6 of previous slide).
27 Example flow contour diagram (contours of velocity magnitude in m/s) of steady channel gas flow passing through a choked 2D-axisymmetricconvergent-divergent nozzle moving from left to right into the openatmosphere; viscous-flow CFD simulation via FLUENT V Diagramshows upper half of flow field, with flow centerline along the bottomboundary. A standing normal shock is evident in the nozzle divergencesection, indicative of an overexpanded nozzle. The flow is separated fromthe nozzle expansion wall downstream of the nozzle throat, resulting in anexhaust jet that is of relatively constant cross-sectional area as it extendsand expands downstream.
28 Specific impulse (instantaneous): Average specific impulse:
36 Combustion Review 18 amu, water vapour 8 : 1 Reaction, ideal result:8 : 1stoichiometric oxidizer-to-fuel ratioMolecular mass of ideal stoichiometric product ofcombustion (reaction):18 amu, water vapour+ heat energy
37 Non-ideal chemical reaction: Molecular mass of non-ideal product of combustion :
38 Resulting gas specific heat: Resulting gas ratio of specific heats:
39 Flame StructurePremixed laminar flame, first category; process of combustion is driven predominantly by pressureTurbulent diffusion flame, second category; process of combustion is driven predominantly by mixingCommonly in propulsion system combustors, flame is a combination of the above two