A Review of Fuel Pre-injection in Supersonic, Chemically Reacting Flows

[+] Author and Article Information
Viacheslav A. Vinogradov

 Central Institute of Aviation Motors, Moscow, Russiaslava@postman.ru

Yurii M. Shikhman

 Central Institute of Aviation Motors, Moscow, Russia

Corin Segal

 University of Florida, Gainesville, FLcor@ufl.edu

Appl. Mech. Rev 60(4), 139-148 (Jul 01, 2007) (10 pages) doi:10.1115/1.2750346 History:

Developing an efficient, supersonic combustion-based, air breathing propulsion cycle operating above Mach 3.5, especially when conventional hydrocarbon fuels are sought and particularly when liquid fuels are preferred to increase density, requires mostly effective mechanisms to improve mixing efficiency. One way to extend the time available for mixing is to inject part of the fuel upstream of the vehicle’s combustion chamber. Injection from the wall remains one of the most challenging problems in supersonic aerodynamics, including the requirement to minimize impulse losses, improve fuel-air mixing, reduce inlet∕combustor interactions, and promote flame stability. This article presents a review of studies involving liquid and, in selected cases, gaseous fuel injected in supersonic inlets or in combustor’s insulators. In all these studies, the fuel was injected from a wall in a wake of thin swept pylons at low dynamic pressure ratios (qjetqair=0.61.5), including individual pylon∕injector geometries and combinations in the inlet and combustor’s isolator, a variety of injection conditions, different injectants, and evaluated their effects on fuel plume spray, impulse losses, and mixing efficiency. This review article cites 47 references.

Copyright © 2007 by American Society of Mechanical Engineers
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Figure 18

Schematic diagram of kerosene injected in an axisymmetric scramjet model: I, II, and III hydrogen injector sets, Tf=300K, 1-liquid kerosene jets. First cone angle was 18deg followed by two additional cones of 5deg each.

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Figure 16

Diagram of the 3-D inlet. All dimensions are in mm.

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Figure 17

Mixing efficiency for C2H4 injection at M∞=6 Ref. 44

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Figure 1

Model of jet (3) injected behind a thin pylon (2) transverse to the wall (1) in supersonic flow

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Figure 2

Schematic diagrams of pylon configurations: (a) triangular, (b) rectangular, (c) rectangular with side wall releases for enhanced aerodynamic jet breakup

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Figure 3

Images of spray plumes injected in air (1) at M∞=3, q¯=1.2 behind pylons (2). The injectant (3) was kerosene RT: (a) direct lighting with triangular pylon as shown in Fig. 2, (b) shadowgraph of higher viscosity jet, T6 with rectangular pylon with side wall release of the type shown in Fig. 2, (c) schlieren image shows clear penetration of the jet to the pylon’s height followed by an abrupt jet breakup, (d) shadowgraph of the jet (4) interacting with a shock wave (5) generated by the 10deg inclined plate.

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Figure 4

Schematic diagrams of jet penetration and breakup using (a) a triangular pylon, or (b) a rectangular pylon with side wall release to enhance the aerodynamic jet breakup

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Figure 5

Penetration of kerosene at M=3 and q¯=1.4 shows an order of magnitude higher penetration over the case without a pylon at the same dynamic pressure ratio. The jet penetration is higher as the jet is closer to the pylon’s base.

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Figure 6

Droplet diameter d32 measured in the axial direction indicates substantial droplet breakup is completed within the first 100 jet diameters for selected flow conditions and pylon dimensions. The finest mist depends primarily on the jet properties and the intensity of the aerodynamic interaction.

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Figure 7

Injection and flameholding configurations for isolator fuel injection. The facility was geometrically symmetric with fuel injected from one side only.

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Figure 8

Shadowgraph images in the isolator. The dashed white lines indicate pylon location (a) water injection without pylon, q¯=0.7, (b) JP-10 injection and combustion, Tt,air=300K, q¯=0.7, ϕ=0.41, (c) JP-10 injection and combustion, Tt,air=300K, q¯=0.7, ϕ=0.53.

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Figure 9

Diagram of the isolator∕combustion chamber and injection configurations: 1, isolator; 2, combustion chamber; I–IV fuel injector sets

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Figure 10

View of injectors: (a) first injector set: 1–pylons, 22.4deg angle; 2–wall jet orifices; (b) upstream view in the isolator: 3–pylons of the first set, 4–strut injectors, 5–second injection set

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Figure 11

Normalized combustion efficiency for different fuel supply configurations

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Figure 12

Inlet photograph indicating the pylons location on the compression surface: 1–10deg wedge, 2–cowl, 3–pylons, 4–side walls, 5–wall pressure taps

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Figure 13

Schlieren images of the inlet flowfield at M=3.5 and α=5deg. 1–pylon, 2–cowl, 3–wedge, 4–initial shock wave, 5–upper boundary of bleed slot, 6–leading edge of the inlet side wall, 7–liquid fuel plume. (a) Without injection; (b) liquid injection at ϕ=0.22.

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Figure 14

Pressure recovery at the inlet’s exit with and without pylons indicates minimal effect of pylon’s installation

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Figure 15

Effect of mass flow addition in the inlet on pressure loss. Two angles of attack show a similar trend.




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