CN108151065A - Tiny engine combustion chamber is to spraying formula evaporation tube - Google Patents

Abstract

The present invention provides a kind of tiny engine combustion chamber to spraying formula evaporation tube designing scheme, it can effectively enhance the mixing of fuel oil and air, the ignition performance of strengthen burning room increases the mixed gas residence time, improves fuel evaporation atomizing effect.Multiple recirculating zones are formed in burner inner liner cavity during to spray formula evaporation tube to spraying mixed gas, the mixed gas not being sufficiently atomized out of evaporation tube will obtain further evaporating atomization after recirculating zone is entered, and wellatomized mixed gas can effectively improve efficiency of combustion.Residence time is extended mixed gas in the combustion chamber simultaneously so that burning is more abundant, and gas flow temperature has certain raising, promotes the evaporation atomization of fuel oil in evaporation tube.Due to the presence of recirculating zone, flame is easily stablized in the combustion chamber so that engine enhances the adaptability of environment.

Description

Micro-engine combustor to jet evaporator tube

technical field

The invention belongs to the field of micro-engine combustion chambers, and in particular relates to a design of a novel evaporation tube which can effectively improve the fuel atomization and evaporation effect in the combustion chamber, thereby improving the combustion efficiency in the micro-combustion chamber.

Background technique

Micro power system has become a research hotspot at home and abroad in recent years, among which micro turbine engine is one of the most promising power, with the advantages of small size, light weight, large output energy and high density. The design of the micro-combustion chamber is the key link and the most important part of the micro-turbine engine. Compared with the conventional-scale combustion chamber, this type of combustion chamber has the characteristics of small characteristic size and large surface-to-volume ratio, resulting in short airflow residence time and heat loss. large, leading to the occurrence of combustion instability.

Although relevant research work on micro-combustion chambers has been carried out at home and abroad, there are few studies on the flow characteristics and performance of micro-combustion chambers. For micro-engines (thrust less than 50daN) combustion chambers, there are mainly two types: direct-flow annular combustion chamber and Backflow annular combustion chamber, high-performance micro-engines mostly adopt direct-flow annular combustion. Due to cost and space constraints, in terms of fuel atomization and evaporation, the evaporation tube type with simple structure is basically used for fuel supply. This fuel supply method can be used in a short High combustion performance can be obtained under the condition of combustion residence time. Among them, the annular combustion chamber of the evaporator tube type has no fuel injector and centrifugal oil thrower in structure. The liquid fuel passes through the evaporator tube and gradually evaporates into a gaseous state. Before combustion, it is initially mixed with the air in the evaporator tube. At the same time, it has neither a swirler nor a blunt body used to generate a stable vortex. It relies on many regular mixing holes on the inner and outer walls of the flame tube. The holes and the airflow at the outlet of the evaporator tube generate a stable vortex to fully burn the fuel. . The annular combustion chamber of the evaporator tube type has many advantages such as excellent atomization, high combustion efficiency, low oil supply pressure, low cost and light weight. In this kind of combustion chamber, the structural design of the evaporation tube plays a key role in the atomization and combustion efficiency in the combustion chamber.

For the design of the evaporator tube structure, whether it is "L" type or straight tube type, the effect of atomization and evaporation of fuel oil through a simple high-temperature evaporator tube is limited. How it is distributed in the oil mist field has a great influence on the distribution of the entire oil mist field and the evaporation and atomization effect of fuel oil. In turn, the performance of the micro-combustion chamber can be improved, and there is great research prospect in this regard.

Contents of the invention

The technical problem to be solved by the present invention is to propose a design scheme of a counter-spray evaporator tube capable of enhancing the effect of fuel vaporization and atomization in a micro-combustion chamber. This technology adopts the way of two evaporating tubes spraying on each other. Advantages: two evaporator tubes spraying against each other can form multiple recirculation zones inside the flame tube, so that the fuel can be fully atomized in the recirculation zone, which increases the residence time of fuel in the combustion chamber, is more conducive to ignition, and expands the flameout boundary , At the same time, it can also promote the full mixing of fuel and air.

Technical solutions

The object of the present invention is to provide a micro-engine combustor-to-spray evaporator tube.

Technical scheme of the present invention is as follows:

The structure design scheme of micro-combustion chamber spraying evaporating tube is characterized in that: the distribution of evaporating tubes adopts a scheme of spraying evaporating tubes, one of which extends from the front end of the flame tube, and the other evaporating tube extends from the flame tube The outer wall surface of the two evaporating tubes is opposite to each other.

The evaporating tubes mentioned above are evenly distributed inside the flame tube along the circumferential direction, and the structural form of the evaporating tubes adopts a straight cylindrical or L-shaped evaporating tube. The diameter of the evaporating tube is between 5mm and 12mm, and the distance between the outlets of the two evaporating tubes is between 5mm and 10mm, which is determined by the actual performance requirements; the number of evaporating tubes distributed along the circumferential direction depends on the flow rate and flow field of the flame tube and evaporating tubes 4 to 32 need to be evenly distributed.

The present invention has the following beneficial effects:

The counter-jet evaporator tube is used in the combustion chamber of the micro-engine. Different from the ordinary evaporator tube, the counter-jet evaporator tube can form multiple recirculation zones inside the flame tube. A part of droplets with large particle size exists, and these droplets will be atomized more fully in the recirculation zone. Moreover, good flame combustion conditions are provided due to the existence of the recirculation zone. Good fuel atomization and good ignition performance are of great help to improve the performance of the combustion chamber.

Description of drawings

Figure 1: The overall three-dimensional diagram of the jet evaporator tube

Figure 2: Front view of spray evaporator tube

Detailed ways

The present invention will be further described now in conjunction with accompanying drawing:

Referring to Fig. 1, the present invention provides a new micro-engine combustor-to-spray evaporator tube that can effectively improve fuel vaporization and atomization to enhance ignition performance. Fig. 1 is a schematic diagram of the three-dimensional structure of a micro-combustor evaporation tube with a counter-spray structure, and Fig. 2 is a front view of the structure of the micro-combustor evaporation tube. The combustion chamber is the core component of the micro-engine. The micro-engine is small in size, compact in structure, not easy to flow and burn, and the combustion residence time is short, on the order of a few milliseconds. The formation of multiple recirculation zones has a significant effect on enhancing fuel atomization, promoting oil-gas mixing, and enhancing ignition performance.

At present, the fuel atomization of the micro-engine combustion chamber mainly depends on the performance of the evaporation tube. With the increase of the thrust-to-weight ratio of the engine, the requirements for the fineness of the fuel atomization are also getting higher and higher. The counter-spray evaporating tube provided by the present invention is shown in Fig. 1 and sprays the mixed gas oppositely at a certain speed, and the mixed gas injected by the two evaporating tubes is an aerodynamic blunt body to form a recirculation zone in the combustion chamber. For the fuel that is incompletely atomized in the evaporator tube, after entering the recirculation zone, it will be further atomized under a larger pressure gradient, and at the same time make the oil and gas mix more uniform, and because of the existence of the recirculation zone, the mixture in the combustion chamber will be prolonged. The residence time is conducive to combustion. Compared with the combustion chamber with a single evaporator tube, the temperature inside the flame tube of the combustor with a counter-spray evaporator tube is higher, which enhances the heat exchange between the high-temperature gas in the flame tube and the evaporator tube, thereby promoting the evaporation and atomization of fuel in the evaporator tube . In addition, due to the existence of the large recirculation zone, the stability of the flame in the combustion chamber has been further improved, so that the adaptability of the engine to the environment will also be enhanced. Thereby, the combustion efficiency of the combustion chamber is greatly improved, and the overall performance of the micro-engine will be further improved.

Claims (4)

1. The structural design scheme of the micro-engine combustion chamber's opposite-spray evaporator tube is characterized in that two evaporator tubes are used to spray the mixed gas in opposite directions on the same horizontal line. 2. The structural design scheme of a micro-engine combustor's counter-injection evaporator tube according to claim 1, characterized in that: 4-32 counter-injection evaporator tubes are uniformly distributed along the circumferential direction in the annular combustion chamber. 3. The structure design scheme of a micro-engine combustor against-spray evaporator tube according to claim 1, characterized in that: the distance between the outlets of a group of two-spray evaporator tubes is between 5 mm and 10 mm. 4. The structural design scheme of a micro-engine combustor-to-spray evaporation tube according to claim 1, characterized in that: the diameter of the evaporation tube is between 5 mm and 12 mm; the shape of the evaporation tube is divided into straight cylinder type or L type .