JPS6236560A - Device and method for measuring luminosity of hydrocarbon fuel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method and apparatus for measuring the luminance of hydrocarbon fuels, particularly jet fuels used in aircraft turbine engines.

[Conventional technology]

Luminon tea produced by burning aircraft turbine fuel has important implications for the performance and long-term durability of aircraft jet engines. As the amount of radiant heat transferred to the combustor liner wall increases, the luminon tee also increases, which increases the wall surface temperature and ultimately reduces the life of the combustor due to loss of structural integrity. The luminosity of the flame is also related to the amount of soot generated from the fuel, which is an important requirement for the generation of emitted smoke.

Standard specifications for fuel quality have been developed to ensure proper combustion characteristics with respect to flame luminosity and soot production at all times. These specifications are based on ASTM test methods and include a smoke point test (D +322) and a luminometer number test (D174o). However, because these tests were conducted under conditions different from those in an actual engine combustor, it was difficult to correlate these results with engine performance. Modifications and instrumentation have been used to measure the luminosity of the flame and its effect on liner temperature as a function of fuel type. , this method has several drawbacks: 1. Results are highly dependent on the type of combustor used due to design idiosyncrasies such as injection method, cooling method, and physical geometry.

2. This combustor test facility is complex and has high construction and operation costs. It requires a large number of fuel samples, which exceeds the amount of experimental fuel available.

[Problem that the invention seeks to solve]

A first object of the present invention is to provide an improved method for measuring jet fuel luminon tee to predict combustor liner temperature rise. Another object of the invention is to provide a measuring device as described above which is relatively simple to construct and easy to operate.

[Means for solving problems]

a venturi at or near its upper end; a capillary having an open end disposed near the constriction of the venturi; and a capillary for directing a liquid hydrocarbon flow from the capillary into the venturi and thus into the tubular member. a gas injector for injecting a gas stream into the space defined between the venturi tube and the capillary to form a series of hydrocarbon liquid droplets; an igniter disposed at or near the top of the tubular member for burning the combustible gas in the presence of oxygen and igniting the droplets of hydrocarbon liquid; and a droplet of hydrocarbon fuel flowing through the tubular member. An object of the present invention is to provide a device for measuring the luminosity of a combusted liquid hydrocarbon fuel, comprising a luminometer for measuring the luminosity when the fuel is combusted.

In another embodiment, the present invention provides a method of determining the luminosity of a liquid hydrocarbon fuel by burning it in the apparatus described above.

[For production]

An example of an arrangement of equipment that can be used in the method of the invention is shown in FIG. The device has a droplet generator (burner housing) in communication with a combustion duct 6 (i.e. combustion chamber 6) equipped with a photodiode 10 and an oscilloscope for measuring the luminosity due to combustion of liquid fuel droplets.
It is mainly composed of 8.

FIG. 1 shows schematically a portion of the liquid fuel droplet generator of this device, which is essentially surrounded by an outer vertical concentric tube 12 through which a gas (e.g. nitrogen) flows. It consists of a vertical capillary tube 2 through which liquid flows.

By separating the liquid fuel droplets from the capillary tip before they are fully formed, a stream of small, preferably uniformly sized and evenly spaced droplets is created.

This separation is effected by a pulling force created by an annular gas flow (preferably an inert gas flow) through a capillary tip located at the constriction of the venturi 16. When the gas passes through the capillary tip, it is accelerated by the venturi,
After passing through the venturi, the speed is reduced.

The droplets thus created are smaller in diameter than those produced by "natural" separation, which occurs when the weight of the droplet overcomes surface tension at the capillary tip and moves away from the capillary tip. The size, spacing, period and initial velocity of the droplets can be controlled by varying the liquid flow through the capillary, the gas flow through the capillary tip and the capillary dimensions. Accurate metering of this liquid flow is controlled by a l5CO pump,
Meanwhile, a constant gas flow is provided by a digital mass flow controller.

Precise positioning of the capillary tube relative to the venturi can be achieved by an xyz translation stage 14 driven by a micrometer attached thereto.

A complete schematic diagram of the combustion device is shown in Figure 2. The high temperature combustion environment for burning the droplets consists of after-combustion gases from a narrow premixed (typically CH6102/N2) laminar flow flat flame supported on an inverted water-cooled burner (flat flame burner) 18. given from. The stoichiometric amount and total flow rate of the gaseous fuel mixture delivered to this burner is precisely controlled and monitored by an adjacent control panel via a needle valve and calibrated flow meter 20.

Additionally, the purge flow of nitrogen gas through the shroud surrounding the burner surface for cooling is also monitored by this panel. In the unlikely event that the pressure in the gas supply path drops or the power supply fails, the burner will be immediately shut off using a combination of pressure switch, relay, and solenoid valve, and flammable gas will be removed from the equipment by continuously purging with nitrogen gas. and cool the combustion duct. Internal cooling of the burner surface and a series of check valves in the gas flow path eliminate the possibility of flame backflow.

The combustion duct 6 is a transparent quartz cylindrical tube.

Its diameter is, for example, an inner diameter of 70 mm, an outer diameter of 74 mm, and a length of vlm. This tube is suspended from the droplet generator 8 by a flange assembly.

Combustion gases are exhausted from the bottom of this duct into an exhaust gas recovery system (not shown). The temperature distribution of the combustion gases in this duct was modified for radiation by a fine wire thermocouple probe ( Pt/6%Rh vs.pt,/so%Rh
) is measured by The droplet generator 8 injects a stream of uniformly spaced, uniformly sized droplets (initial diameter approximately 50-500 microns) through a hole in the center of the burner and into the combustion duct below. It ignites immediately and burns after a certain trigger time. Stroboscopic back illumination of the droplet stream and a stepped microscope/camera 2 viewing device can be added to facilitate visual and photographic observation of the burning droplets. Quantitative data, including droplet size, spacing, velocity, and qualitative information, such as qualitative information regarding gas phase soot formation, are obtained directly from the modified photographic record. By moving the camera device along the length of the combustion duct a detailed record of the combustion life of the droplets can be obtained.

For purposes of the present invention, a transparent quartz cylinder is fitted with photodiodes (preferably responsive to a field of view of 0.4 to 1.1 microns) placed at multiple locations along the combustion duct. There is.

As shown in FIG. 2, two photodiodes are used for drop velocity measurement and optical triggering of the stroboscopic photographic device described above.

Operation of the device begins by introducing fuel gas, air, and diluent to the burner at the top of the device. This gaseous fuel mixture flows downward and is ignited by a propane torch.

When the liquid fuel pump is activated, sample is ejected through a nozzle at the top of the device, creating droplets.

The injection speed of this liquid fuel is important because it affects the droplet spacing. When the droplets fall down through the hot gas, they ignite and burn. A photodiode 10 is coupled to the burning droplet stream at a predetermined location. The luminosity of each droplet is detected and displayed as a waveform on the oscilloscope, and the average peak intensity is read and recorded. A luminosity distribution along the combustion duct is obtained by moving the photodiode up and down the tube. The maximum luminosity is used to characterize the luminosity of the fuel.

EXAMPLES Tests using the above device included luminosity measurements of individual combustion droplets of fuel using fort diodes (response field of view, 0.5 m) placed at multiple locations along the length of the combustion duct.
4 to 1.1 microns). Intensity was recorded as the peak photodiode output voltage displayed on the oscilloscope. The initial droplet diameter was kept constant at 350 microns, and the droplet period and initial velocity were kept at 15 drops per second and 4 m/s, respectively. The gas flow and temperature distribution in the combustion duct were also maintained at constant values of 3-4 m/s and 1100-2000°K, respectively. The above parameters were fixed so that the only variable during each run was the fuel composition.

The experimental conditions used in the droplet type device described above are the same as those in an actual gas turbine, except for the operating pressure (1 atm vs. 15 atm). For example, a typical spray droplet size is 10
0 microns or less, and the relative droplet/gas velocity is small. - The spray flame temperature in the secondary zone is 2500°K and the turbine inlet temperature is above 800°K.

Table 1 Measured luminosity Jet A 3.8 Jet B 4.2JP
4 2.6JP5
4.1*USA
F JP8 3.0USAF
JP8-All 8.3USA
F JP8-AD2 5.8US
AF JP8-AD self 6.6T
JSAF JP8-AD4 6.
8 experimental JP7 + 6 volume % 1-MN +,
! +*tlsAF fuel is supplied by the Air Vehicle Aviation Propulsion Research Institute, and the report ◆AFAP L-TR-79-201
These correspond to fuels ◆2, 4, 5, and 6.7 described in No. 5, respectively.

Luminosity data for each fuel is completely reproducible. These data were qualitatively equivalent to those obtained with the combustor facility and correlated well with the liner temperature rise.

A typical luminosity distribution obtained under these conditions when testing commercial Gen) A fuel is shown in FIG. Figure 4 shows a series of luminosity distributions for aromatic-doped JP7 fuel, where 1-MN means 1-methylnaphthalene. Table 1 shows the vehicle minosity values for multiple fuels and fuel mixtures, and Figure 5 shows the USAF report AF for the J79 combustor for multiple fuels.
FIG. 3 is a diagram plotting vehicle luminosity data measured with our device against the peak liner temperature rise described in AP L-TR-2015.

From this data, once the luminosity distribution of a fuel is measured, the liner temperature caused by combustion of that fuel and the expected life of the liner can be predicted. The predicted combustor liner temperature rise from this data is given below.

During flight: During takeoff: Also, the life of the combustor liner is given by: Relative life: , o(0,283-0,0811M)'
/l (Peak 3' where the life is U, SAF JP4
Based on fuel (T-beak = 425℃, relative life = 1.o)
It is defined as a relative value to the life corresponding to combustor operation under takeoff conditions.

The devices and methods described above have many advantages. In other words, a small amount of sample is sufficient. There is direct and complete optical access to the burning droplets.

Easy and quick measurements can be performed with good reproducibility. The effects of spray action, fluid dynamics and physical form of the device can be eliminated or minimized. The operating temperature of the device is the same as that of the actual engine. The droplets created and the relative flow field are the same as in the actual engine or the engine to be used.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a part of the test apparatus of the present invention, in which droplets of liquid hydrocarbon fuel are created; FIG. 2 is a schematic diagram of the entire test apparatus; FIGS. 3 and 4 are the same as described above. Chart showing the luminosity distribution of several jet fuels as the fuel droplets pass through the device and burn. Figure 5 shows the peaks of the combustor liner corresponding to the luminosity measurements expressed in terms of photodiode output voltage. A chart showing temperature @ In the figure: 2. Capillary tube, 6. Combustion duct, 8. Droplet generator (Burnare Uzing)
10...Photodiode, 12...Vertical concentric tube, 1
4. Φ moving stage, 16... Venturi, 18...
(Water-cooled) Burner (Flat flame burner
口■ S Noburenocity (output/holt to photoquio) procedural amendment September 4, 1986

Claims (1)

[Scope of Claims] 1. An apparatus for measuring the luminosity of a burning hydrocarbon liquid fuel, comprising: (a) a venturi disposed at or near the upper end of a transparent tubular member; (b) the above. (c) a liquid injector for injecting a stream of liquid hydrocarbon from said capillary tube into said venturi and thus into said tubular member; (d) said venturi; a gas injector for injecting a gas stream into the space defined between the tube and the capillary to form a series of hydrocarbon droplets; (e) combusting the combustible gas in the presence of excess oxygen; an igniter disposed at or near the upper end of said tubular member for igniting droplets of hydrocarbon liquid; and (f) luminosity of the combusting droplets of hydrocarbon fuel as they flow through said tubular member. Luminometer for measuring. 2. Claim 1 in which the luminometer is a photographic device
Apparatus described in section. 3. The apparatus of claim 1, wherein the luminometer is a photodiode electrically coupled to an oscilloscope. 4. The apparatus of claim 1, wherein the luminometer is a photomultiplier tube electrically coupled to an oscilloscope or a signal averaging device, or both. 5. The apparatus of claim 1, wherein the luminometer is a piezoelectric detector electrically coupled to an oscilloscope or a signal averaging device, or both. 6. (a) introducing a stream of linearly spaced hydrocarbon fuel droplets into a combustion zone; (b) burning the droplets in the combustion zone; and (c) a stream of droplets during combustion. A method of determining the quality of liquid hydrocarbons by measuring the luminosity of the burning liquid hydrocarbons, which consists in measuring the radiation intensity emitted by the liquid hydrocarbons. 7. The method of claim 6, wherein the spacing of the linearly spaced hydrocarbon fuel droplets is uniform. 8. The method of claim 6, wherein the linearly spaced droplets of hydrocarbon fuel are of uniform size. 9. The method of claim 6, wherein the combustion zone comprises a stream of heated gas and air or oxygen. 10. The method of claim 6, wherein the combustion zone further comprises a diluent gas. 11. The method according to claim 6, wherein the temperatures in the combustion zone are 1100°K and 2000°K. 12. The method of claim 6, wherein the combustion zone comprises a high temperature combustion environment provided by post-combustion gas obtained by combustion of a lean premix of methane, oxygen and nitrogen components. 13. The method of claim 6, wherein the intensity of radiation from the combustion stream of hydrocarbon fuel droplets is measured at multiple locations in the stream. 14. The method of claim 6, wherein the hydrocarbon fuel droplets have a diameter of 50 to 500 microns. 15. Claims 6 to 14 in which the measured strength is used to predict jet engine liner life
The method described in any one of the preceding paragraphs.