Theoretical and experimental aspects of naval fuel drop burning.

Turcoiu, Titi ; Omocea, Ion ; Radulea, Lilian 等

1. INTRODUCTION

Naval fuel burning graphology (Ghia, 1991, 1995) is defined as the scientific discipline concerned with the graphic evolution transposition of intermediate fuel's burning processes, establishing the ignition-burning characteristics, including the governing laws for these changes, depending on the burning conditions and the chemical fuel structure.

Naval fuel burning graphology specific sizes follows from burning oscillogram transformation, experimentally obtained. Burning oscillogram (fig.1) (Ghia, 1995) is the graphical transposition of intermediate naval fuel drop's ignition and burning processes, under some curves shape which are represented in a rectangular coordinate axis system. Time variation [tau] is represented on the abscissa, and radiation intensity variation I on the ordinate, for the burning naval fuel drop, which is transformed in electrical voltage, through amplifying photocell.

For naval fuel this time varying curve of radiation intensity establishes a multitude of ignition-burning characteristics, such as:

--Ignition delay, [[tau].sub.i]; burning time for volatile matters, [[tau].sub.v]; cenosphere burning time, [[tau].sub.c] ; total burning time, [[tau].sub.a] ; cenosphere (Cenosphere is a carbonic residuum, which remains after volatile matters burning from the naval fuel drop. Because it is composed from the non-volatile components of the fuel, cenosphere burning produces in the surface and is governed by solid fuel burning processes rules. Because of the cenospheres, the naval burning fuel is incomplete; also, it pollutes the atmosphere and has abrasive action on the metal parts it has contact with (piston, cylinder, exhaust track). Usually, the cenosphere have close sphere shapes, size of 3 ... 18 [Angstrom]. When they generate through drops burning at high temperature, their structure is compact; when they generate as a result of naval fuel drops evaporation, without burning, the cenosphere has a spongy, fragile structure) delay ignition, [DELTA][[tau].sub.c]; flame radiated energy, converted by the photocell into electrical energy, at volatile matters burning, [E.sub.v]; radiated energy by the burning cenosphere, [E.sub.c]; total radiated energy, [E.sub.t]; maximum radiated intensity at volatile burning matters, [I.sup.m.sub.v]; maximum radiation intensity at burning cenosphere, [I.sup.m.sub.c].

In the burning graphology, for naval fuels systematic differentiation, regarding ignition, burning and radiation some other characteristics are also defined:

--Ignition index, [psi];

--Burning simplex, Sa;

--Ignition and burning complex index, A;

--Radiation index, B;

--Global ignition, burning and radiation index, G;

--Burning volatile matters constant, [k.sub.v];

--Burning constant of the cenosphere, [k.sub.c];

--Total burning constant, [k.sub.a];

--Burning speed constant, [k.sub.Wa].

We will consider the physical burning drop model, in ascendant current, with U speed as shown in figure 2, for the indication of the fundamental equations and limited conditions afferent to naval stationary burning drop.

2.THE COMPONENTS OF BURNING SIMULATOR OF NAVAL FUEL DROP'S BURNING

Graphology method application in ignition-burning characteristics determination imposed reaching a specialized stand, called burning simulator, composed of the following (Ghia, 1995; Radulea, 2007):

--Cylinder, electrically heated, ceramic burning room, arranged in a metallic water cooled shell, through a continuous pumped circulation;

--Fuel drop propulsion device, suspended at quark filament's end, against the burning room;

--Optical device for drop's burning centralization, processing, focusing and visualization;

--Electrical equipment composed of: drop's entering signaling device into the burning room; two photovoltaic translators, electrical signals amplifying and processing block, parasite radiation filtering and compensation devices;

--Two electrical heaters with annexes: the first for burning room's ceramic wall heating, composed of four silica bars; the second one for burning air preheating, with an automatic temperature regulator;

--Computer for data acquisition, processing, posting and storing, resulted from burning oscillograms;

--Syringe charger specialized microscope and ocular interpolator equipped, for a precise drop calibration at imposed experimental sizes, formed and harvested at syringe needle's end.

The covered steps for a naval drop ignition-burning experiment are as follows: dozer syringe loading with warmed fuel probe and air bubbles evacuation; drop's forming, with the initial diameter [D.sub.0] expected at needle's syringe end, by ordered movement of the syringe's system, using a screw mechanism with small step; direct medium diameter measurement verification, using the interpolator microscope; parameters' values program insertion [T.sub.ca 0], [T.sub.a], [D.sub.0], for naval fuels density and for the maximum time destined for ignition-burning processes; drop's drawing from quark filament of drop's naval propulsion device; drop insertion in the center of the burning room, together with acquisition system release and experimental data registering; naval drop ignition and burning; burning oscillogram monitor exposure; times establishing [[tai].sub.i], [[tau].sub.v] and [[tau].sub.c] through oscillogram exploration with monitor's vertical cursor; table experimental processed results and burning oscillogram insertion into the program.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

The burning naval drop's experimental results, that were investigated in this paperwork, were made in the following standard conditions: ambient medium temperature, [T.sub.a] = 290 [+ or -] 1K ; temperature inside the burning room, [T.sub.ca0] = 973 [+ or -] 1K; fuel temperature, [T.sub.c] = 295 [+ or -] 1K ; pressure inside the burning room, [p.sub.ca0] = 103,325 [+ or -] 13kPa; burning room diameter, [D.sub.ca0] = 36 mm; fuel drop initial diameter, [D.sub.0] = 1,8 / 1,9 /2,0 mm ; air leaking regime surrounding fuel drop, estimated through Reynolds criterion, Re=80 /120 /140 ; drop's support and rapid insertion into the burning room by drop's propulsion charger, part of the ignition-burning simulator.

From all fuel probes in the ignition-burning experiment, in the simulator ten drops were drawn and burnt, and the presented results in the paper represents the average of these ten measured and calculated drops.

3. CONCLUSIONS

The naval fuel drop burning oscillogram can be obtained using a burning simulator .

The burning oscillogram offers the ignition-burning characteristics of the naval fuels.

The burning graphology to utilising, in marine filed, in the following cases:

--different types of naval fuels, for a rigorous quality check;

--suppliers' naval fuels, for a correct establishment of acquisition prices;

--customer's naval fuel (beneficiary's), for an optimum adjustment of the naval engines where the fuel is used;

--minimum expenses for quality fuel improvement technologies establishment, by mixture and removing most of the chronofague and expensive experiments, engine made.

4. REFERENCES

Andersen, O. (1998). Use of DFT # 1500 Hammerdown and 1500 V to Condition Heavy Fuels Used in Marine Engine, Ottomans AS Deutschland, Rheinbach, Germany, prospects

Ghia, V.V. (1991). Combustion Graphology of International Fuel Oils. Rev. Roum. Sci. Techn. Elth. Et Energ., tom. 36, nr. 3, pp 379-396,Bucharest,1991

Ghia,V.V. (1995). Graphology characteristics determination for one sort oil burning and three sorts water-oil emulsions ultra sound treated. Research report, nr. 370/30.11.1995, MASTER S.A., Bucharest ,1995

Radulea, L. (2007). Research for naval engines performances improvement by fuel's mixture. PhD. Thesis, public presentation,July 2007,Maritime University of Constanta, 2007

Turcoiu, T., Pruiu, A., Roman, C.& Catrinescu Gh. (1996). Control,monitoring and protection system for marine diesel engine, Technical Publisher House, ISBN 973-31-0922-3, Bucharest,1996

Turcoiu, T. & Radulea, L. (2007). Study of naval fuel drop burning.Paper presented at IMLA's 15th Conferences on MET, Chaguaramas,Trinidad-Tobago,15-19 October 2007