CN115949971A - A fuel nozzle with a spiral channel - Google Patents

Abstract

The invention discloses a fuel nozzle with a spiral channel, which comprises a main oil channel and an auxiliary oil channel, wherein the main oil channel comprises an oil inlet pipeline for fuel oil to enter the fuel nozzle, the spiral channel and a round hole channel, the spiral channel is a circular channel with a spiral surface on one end surface, one end of the spiral channel is communicated with the oil inlet pipeline, the other end of the spiral channel is communicated with the round hole channel, the spiral channel is sleeved outside the auxiliary oil channel, the end surface of one end of the spiral channel, which is connected with the oil inlet pipeline, is a spiral surface, and the spiral surface is spirally sleeved outside the auxiliary oil channel. The spiral channel structure can make the fuel flow in the back along the design direction of spirality, until flowing into rear round hole passageway, the continuous one-way whirl of fuel in spiral channel had both avoided stranded fuel to collect the existence that causes the backward flow district and the piling up of fuel, had increased the flow velocity of fuel again, had reduced the dead time of fuel, very big reduction the fuel temperature and the wall temperature in the fuel nozzle.

Description

A fuel nozzle with a spiral channel

technical field

The invention relates to a fuel nozzle of an aero-engine combustor and its thermal protection structure, in particular to a fuel nozzle with a spiral channel.

Background technique

The fuel nozzle is one of the key components of the aero-engine combustor. In the return combustor, the fuel nozzles are evenly distributed on the head of the flame tube and fixed by the mounting plate bolts on the combustor case. The fuel enters the inner flow channel of the nozzle through the external pipeline, flows through the flow channels of the circular hole, circular channel, swirl groove and other structures to the outlet of the nozzle, and then enters the combustion chamber flame tube through swirl atomization to participate in combustion. The fuel in the nozzle flow channel has a low flow rate under small working conditions, and is prone to oxidative cracking under high temperature conditions. During combustion, the temperature in the flame tube is as high as 2000K. Under the influence of high-temperature gas radiation heat transfer and solid wall heat transfer, the temperature of the fuel oil in the nozzle flow channel continues to rise, and eventually oxidative cracking and coking occur. Coking products will deposit and adhere to the wall surface. When the coking products fall off, they will flow with the fuel flow channel to the nozzle to block the nozzle, affecting the nozzle's spray cone angle, droplet size and other atomization performance, which will lead to insufficient combustion in the combustion chamber. , Combustion efficiency drops, and in severe cases, the engine may stop.

At present, there are two main ways to reduce the fuel temperature rise in the nozzle at home and abroad: one is to rationally design the flow channel structure in the nozzle to reduce the residence time of the fuel in the nozzle; Shrink sleeve structure, or heat insulation tubes are set in the flow channel to reduce the heat transferred from the air to the fuel.

The flow channel structure in the nozzle is usually composed of a circular hole channel and a circular channel. When the fuel enters the circular channel from the circular hole, it flows slowly along both sides to a certain place and then continues to flow backward; when the fuel flows from the circular channel When the ring enters the circular hole channel, the flow area decreases sharply, causing part of the fuel to accumulate. Too low flow rate and accumulation of fuel will lead to too long stagnation time of fuel in the nozzle. Affected by heat transfer between high-temperature gas and wall surface for a long time, the temperature of fuel will rise and coking will easily occur.

Contents of the invention

Purpose of the invention: In view of the above shortcomings, the present invention provides a fuel nozzle with a spiral channel that reduces the possibility of fuel coking in the local low-velocity area of the fuel nozzle on the premise of ensuring that the flow coefficient of the fuel nozzle remains unchanged.

Technical solution: In order to solve the above problems, the present invention adopts a fuel nozzle with a spiral channel, including a main oil channel and an auxiliary oil channel, and the main oil channel includes an oil inlet line for fuel to enter the fuel nozzle, Spiral channel, circular hole channel, the spiral channel is a circular channel with a helicoid end surface, one end of the spiral channel communicates with the oil inlet pipeline, the other end of the spiral channel communicates with the circular hole channel, and the spiral channel is sleeved on the auxiliary Outside the oil channel, the end face of the spiral channel connected to the oil inlet pipeline is a helical surface, and the helical surface is helically sleeved outside the auxiliary oil channel.

Further, both the starting point and the ending point of the helical surface are connected with the oil inlet pipeline. The spiral surface covers part of the outlet of the oil inlet pipeline. The distance difference between the start point and the end point of the helicoid is smaller than the channel length of the circular channel. The inlet of the circular hole passage and the outlet of the oil inlet pipeline are arranged face to face at both ends of the spiral passage.

Beneficial effects: Compared with the prior art, the present invention has the remarkable advantage that, compared with the fuel accumulation caused by the fuel flowing along both sides in the traditional circular channel until they converge, the spiral channel structure can make the fuel flow in a single direction along the designed rotation direction after entering , until it flows into the rear circular hole channel, the fuel continuously swirls in one direction in the spiral channel, which not only avoids the existence of the recirculation area and the accumulation of fuel caused by the collection of multiple strands of fuel, but also increases the flow speed of fuel and reduces stagnation of fuel Time, greatly reducing the fuel temperature and wall temperature in the fuel nozzle. Therefore, under the premise of keeping the flow coefficient of the fuel nozzle unchanged, the possibility of fuel coking in the local low-velocity area is reduced, the thermal protection performance of the nozzle is strengthened, and the working stability and safety of the combustion chamber are finally improved.

Description of drawings

Fig. 1 is the central cross-sectional view of the structure of the double-oil-circuit centrifugal nozzle in the prior art;

Fig. 2 is the sectional view of A-A section in Fig. 1;

Fig. 3 is a schematic diagram of the coking phenomenon that occurs in the actual work of the fuel nozzle in the prior art;

Fig. 4 is the velocity distribution diagram of the center section of the fuel nozzle and the cross section of the circular channel in the prior art;

Fig. 5 is a structural schematic diagram of the circular channel part of the fuel nozzle in the prior art

Fig. 6 is a structural schematic diagram of the annular channel part of the fuel nozzle in the present invention;

Fig. 7 is the velocity distribution diagram of the cross section of the fuel nozzle annular channel in the present invention;

Fig. 8(a) is a fuel temperature distribution diagram in the circular channel section of the fuel nozzle in the prior art, and Fig. 8(b) is a fuel temperature distribution diagram in the circular channel section of the fuel nozzle in the present invention;

Figure 9(a) is a schematic diagram of the highest temperature in the circular channel of the fuel nozzle in the prior art at different external air temperatures; Figure 9(b) is a schematic diagram of the circular channel of the fuel nozzle in the present invention at different external air temperatures Schematic diagram of the maximum temperature inside;

Fig. 10(a) is a schematic diagram of the maximum temperature in the circular channel of the fuel nozzle in the prior art at different external air flow rates; Fig. 10(b) is a schematic diagram of the maximum temperature in the circular channel of the fuel nozzle in the present invention.

Detailed ways

As shown in Fig. 1, Fig. 2 and Fig. 5, the fuel oil in the main oil circuit of the fuel nozzle in the prior art flows into the circular channel 1, the circular hole channel 3, the circular channel 2 and the swirl groove successively through the oil inlet pipeline 4, Finally, it flows to the main nozzle for ejection; the fuel in the auxiliary oil circuit 5 flows into the radial circular hole, the circular channel, the swirl groove and the swirler successively through the oil inlet pipeline, and finally flows to the auxiliary nozzle for ejection; There is an air intake structure. FIG. 3 shows the coking phenomenon of the fuel nozzle in actual work in the prior art. Fuel coking usually occurs at the end surface of the annular channel 1 of the main oil circuit. Fig. 4 is the velocity distribution diagram of the fuel nozzle center section (left) and the annular channel cross section (right). It can be seen that there is a sudden expansion structure at the junction of the oil inlet passage of the main oil passage of the nozzle and the circular channel 1, forming a recirculation zone, where the fuel is easy to stay. Under the working condition of the fuel flow rate of 0.4g/s, the tangential velocity of the fuel is low, only 0.06m/s, and after the fuel enters the circular channel from the oil inlet, it flows to both sides and finally meets the circular channel. At the joint between the ring passage and the small hole of the rear round hole passage, fuel is easily stagnated here.

A fuel nozzle with a spiral channel in this embodiment includes a main oil channel and an auxiliary oil channel. The main oil channel includes an oil inlet line for fuel to enter the fuel nozzle, a circular channel, and a circular hole channel. One end of the circular channel is connected with the oil inlet pipeline, the other end of the circular channel is connected with the circular hole channel, and the circular channel is sleeved outside the auxiliary oil channel, and the inlet of the circular hole channel and the outlet of the oil inlet pipeline are at the two ends of the circular channel. The end faces are arranged face to face, as shown in Figure 6, the end face of the end connecting the circular channel with the oil inlet pipeline is a helical surface, and the helical surface is helically sleeved outside the auxiliary oil passage. The starting point and the ending point of the helicoid are both connected with the oil inlet pipeline, the helicoid covers part of the outlet of the oil inlet pipeline, and the distance difference between the starting point and the ending point of the helicoid is smaller than the channel length of the circular channel.

The fuel nozzle in this embodiment improves the circular channel 1 with equal longitudinal section into a spiral channel with variable longitudinal section. The connection surface is a circular plane, so the fuel flows through the front oil inlet pipeline, and a part of the fuel flows into the helical surface along the axial direction of the oil inlet pipeline to cover the rear side of the outlet of the oil inlet pipeline, and after being guided by the helical surface, it flows circumferentially along the spiral channel until It flows into the round hole channel connected to the rear; another part of the fuel flows out through the side of the height difference between the oil inlet pipe and the helical surface, and swirls in one direction along the circumference of the helical channel, that is, flows from the wide section position to the narrow section position in one direction until it flows into the rear Connected circular hole channel.

The velocity distribution diagram of the cross-section of the spiral channel in the fuel nozzle structure shown in Figure 7, it can be seen that the fuel flows in one direction in the cross-section of the spiral channel, and the tangential velocity increases significantly, compared with the circular channel of the common nozzle , the maximum value increases from 0.06m/s to 0.3m/s, and the tangential velocity increases along the flow direction.

During combustion, the temperature at the head of the combustion chamber flame tube is as high as 800k to 1400k, so a large air domain of 5m/s and 800K is set outside the nozzle to simulate the environment outside the nozzle body during combustion, and the circular channel of the common fuel nozzle and the present invention are analyzed. Fuel temperature in the spiral channel of the fuel nozzle. The fuel temperature distribution diagram in the passage section of the fuel nozzle is shown in Fig. 8(a) and Fig. 8(b). It can be seen that the temperature distribution on the circular channel section of the fuel nozzle in the prior art is symmetrical, and the temperature near the small hole of the oil inlet passage is the lowest, which is 300K; The temperature near the outer wall is the highest, about 408K. In the fuel nozzle in this embodiment, the temperature in the cross section of the spiral channel rises along the flow direction, but the rise is small, the lowest temperature near the small hole of the oil inlet pipeline is 300K, and the highest temperature is about 350K at the end position along the flow direction. The maximum temperature of the original nozzle dropped by 58K.

Figure 9(a) and Figure 9(b) show the maximum temperature diagram in the annular channel of the fuel nozzle under different external air temperatures. And Fig. 10(a) and Fig. 10(b) show the maximum temperature diagram in the annular channel of the fuel nozzle under different external air flow rates. It can be seen that the higher the temperature of the outside air and the greater the flow rate, the temperature of the fuel in the fuel nozzle in the prior art and the fuel nozzle in this embodiment also rises accordingly, but the highest temperature in the fuel nozzle in this embodiment It is lower than the highest temperature in the fuel nozzle in the prior art under the same working condition.

In the aforementioned embodiments, the spiral channel structure significantly increases the fuel flow velocity, reduces the fuel residence time, lowers the fuel temperature in the nozzle, improves the thermal protection performance of the nozzle, and reduces the possibility of fuel coking in the nozzle.

Claims (5)

1. A fuel nozzle with a spiral passage, comprising a main oil passage and an auxiliary oil passage, characterized in that the main oil passage includes an oil inlet pipeline for fuel to enter the fuel nozzle, a spiral passage, a round hole channel, the spiral channel is a circular channel with a helicoid end surface, one end of the spiral channel communicates with the oil inlet pipeline, the other end of the spiral channel communicates with the round hole channel, and the spiral channel is sleeved outside the auxiliary oil channel, The end face of the end connected to the oil inlet pipeline of the spiral channel is a helical surface, and the helical surface is helically sleeved outside the auxiliary oil channel. 2. The fuel nozzle according to claim 1, characterized in that, both the starting point and the ending point of the helical surface are connected to the fuel inlet pipeline. 3. The fuel nozzle according to claim 2, wherein the spiral surface covers part of the outlet of the oil inlet pipeline. 4. The fuel nozzle according to claim 2, wherein the distance difference between the start point and the end point of the helical surface is smaller than the channel length of the circular channel. 5. The fuel nozzle according to claim 4, characterized in that, the inlet of the circular hole channel and the outlet of the oil inlet pipeline are arranged facing each other at both ends of the spiral channel.

Images