A test system and method for evaluating the effect of liquid film cooling on a coated combustion chamber wall surface

Abstract

The invention discloses a test system for evaluating liquid film cooling influence by a wall surface of a coating combustion chamber and a method thereof. Based on a liquid dropping speed measured ina laboratory, a particle size and a heatable temperature-control real combustion chamber coating test piece capable, a real liquid drop wall-impingement process is simulated, a development condition after liquid drop wall impingement can be captured through high-speed photography, a critical Weber number of liquid drop fragmentation is determined, by changing the liquid drop incident Weber numberand test piece temperature, a dividing mechanism and a mathematics model of liquid drop development condition changed with the incident Weber number and the test piece temperature are found, and a guidance centrifugal-type nozzle design is used so that a liquid drop group falls into an ideal mechanism scope during a wall-impingement combustion process.

Description

technical field [0001] The invention relates to a test system and method for evaluating the effect of liquid film cooling on the wall surface of a coating combustion chamber, belonging to the field of aerospace propulsion technology. Background technique [0002] Centrifugal liquid rocket engine is an important category of space two-component attitude-orbit control engine, which is named for its use of centrifugal injector as a device for propellant atomization and mixing. This kind of engine has good flame maintenance ability, and can stably ignite in a wide range of mixing ratio. Its natural injection uniformity makes the engine have very good ignition safety and working reliability. [0003] The centrifugal engine uses the swirl action of the centrifugal nozzle to make the oxidant and the combustion agent form a hollow atomized liquid cone respectively, and enter the combustion chamber for evaporation, mixing and combustion. In the combustion chamber, most of the liquid ...

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Problems solved by technology

Therefore, on the one hand, the impact of the propellant spray on the wall is related to the cooling characteristics of the engine, and on the other hand, it determines the distribution and mixing state of the two propellant vapors. In addition to affecting the performance of the engine, if the mixing is uneven, it will easily spread Local high temperature is formed during the combustion process, which in turn destroys the liquid film, resulting in an increase in engine operating temperature and a decrease in reliability

[0005] Therefore, it is first necessary to quantify the cooling reasonably. Excessive cooling caused by excessive droplet attachment to the wall can effectively reduce the wall temperature, but at the same time, the low-oxygen mixture in the border area will cause ineffective combustion and reduce engine performance; secondly, it is necessary to achieve high-efficiency mixing Mixing, through the effective action of the wall, more fuel can rebound and splash into the oxygen-enriched central area to participate in combustion, which can effectively improve the specific impulse of the engine

[0006] At present, the development of centrifugal engines, especially the evaluation of cooling effects, is mainly carried out through a large number of test runs, especially for the lack of support for basic research on the mechanism of liquid film cooling, and the consideration of various factors affecting cooling is not comprehensive enough. Establish the relationship between the atomization parameters, the state of the wall surface and the final ignition temperature, and the verification cost is very high. Usually, the information data such as the velocity, particle size and shape of the droplet hitting the wall, and the thickness and length of the formed liquid film Unable to obtain, lack of clear guidance for further optimization of the engine

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