CN101737805B - Low-cost inside diameter-variable combustion chamber and design and test method thereof - Google Patents

Abstract

A low-cost variable internal diameter combustion chamber and its design and test method belong to the field of combustion chamber structure design methods. Combustion chamber includes: head, body and nozzle part. The combustion chamber adopts a heat-capacitating structure, and the material is pure copper with high thermal conductivity, and the body is divided into two parts, the inner bushing and the outer sleeve. Firstly, thermal analysis calculation is used to obtain the size and number of the outer sleeve according to the change of inner diameter. A method in which an outer sleeve is matched with multiple inner bushings to achieve a variable inner diameter test. The processing of the inner bushing and the outer sleeve is completed, and the clearance is guaranteed through tolerances. The combustion chamber material can be saved, the test cost can be reduced and the combustion chamber test period can be shortened.

Description

Low cost variable inner diameter combustor and its design and test method

【Technical field】

The invention relates to a low-cost variable internal diameter combustion chamber and its design and test method. The invention particularly relates to a combustion chamber with a variable inner diameter applied to a liquid rocket engine and its design and test method.

【Background technique】

In the development process of rocket engine thrust chamber, especially in the development process of the injector as the main component of the thrust chamber, in a large number of initial research stages, in order to fully carry out experimental research, it is often necessary to change the diameter of the combustion chamber. Obtain data under different working conditions.

In the combustion test research on the ground, two types of combustion chamber structures are generally used, namely heat capacity type and water cooling type. Compared with the regenerative cooling method, the heat capacity structure has the advantages of simple structure, low cost, and easy maintenance. Although it has the disadvantage of short duration of a single test, it generally does not require a long test in the initial test stage of the thrust chamber. Therefore, the heat capacity structure is widely used in the research of the initial stage of the thrust chamber combustion test. In order to save costs and facilitate measurement, heat capacity combustion chambers are generally made of high thermal conductivity materials (such as: pure copper) as a whole.

Generally, the experimental research carried out under different combustion chamber diameters adopts the following two methods: 1. Calhoon, D., Ito, J. and Kors, D., "Investigation of Gaseous Propellant Combustion and Associated Injector-Chamber design Guidelines-lines , "[R] Aerojet Liquid Rocket Company, NASACR-121234, Contract NAS3-13379, July 1973. Adopting an integral combustion chamber structure with different inner diameters, that is, when it is necessary to change the inner diameter test, the combustion chamber is replaced as a whole. This method is simple It is easy to do, but because it is an integral replacement, when there are many working conditions with different inner diameters to be tested, the same number of integral combustion chambers must be designed. In order to have good thermal protection in the high-temperature and high-pressure environment of the rocket engine, the parts are designed to be large in size and heavy in weight. However, when a large number is used, the cost will increase linearly, and the heavy weight is difficult to replace. 2. Only one heat-capacity combustion chamber is used, and the test progress is arranged according to the test needs: first conduct the test of the small-sized inner diameter, and then expand the inner diameter to carry out the experimental research of the large-sized inner diameter. This method uses only one combustion chamber , the cost is the lowest; but it is not possible to flexibly carry out the exchange test between different inner diameters. For example, in the experimental research, it is often necessary to conduct a small-scale test after a large-scale inner-diameter test, so this method is not applicable. It strictly limits the process used; and this method needs to continuously modify the inner diameter, which will inevitably increase the time cost.

【Content of invention】

The object of the present invention is to provide a low-cost, heat-capacitating combustion chamber that can be easily replaced for the experimental research of the combustion inner diameter and its design and test method, especially when a large number of inner diameters is required.

A low-cost variable internal diameter combustion chamber and its design and test method belong to the field of engine combustion chamber tests. Combustion chamber includes: head, body and nozzle part. The combustion chamber adopts a heat-capacitating structure, and the material is pure copper with high thermal conductivity, and the body is divided into two parts, the inner bushing and the outer sleeve. The combustion chamber head, nozzle and body structure are designed respectively. When designing the body, thermal analysis calculation is firstly used to obtain the size and number of outer sleeves according to the needs of inner diameter changes. During the test, an outer sleeve is matched with multiple inner bushings to achieve a variable inner diameter test method, and the number of inner bushings is equal to the number of required inner diameters. The processing of the inner bushing and the outer sleeve is completed, and the clearance is guaranteed through tolerances. The sealing position of the combustion chamber body is located at both ends of the inner liner.

The advantages and positive effects that the variable inner diameter combustion chamber of the present invention and its design and test method have are: (1) due to only adopting the outer sleeve that is much less than the required inner diameter size number, and the outer sleeve covers the overall combustion The volume occupied by the chamber structure is large and the cost ratio is high, so the designed structure cost is low, especially in the design of a large-sized combustion chamber, which can save a lot of cost; (2) due to the use of an easily removable inner liner Because of the sleeve structure, the inner diameter of the combustion chamber can be freely and flexibly changed for experimental research, which is convenient for application and can be flexibly adapted to the progress of the test. This method has a wide range of applications and can be extended to the application of nozzles and other parts.

【Description of drawings】

Figure 1 is a schematic diagram of the assembly of the variable inner diameter combustion chamber

【Detailed ways】

The present invention will be further described below with examples in conjunction with the accompanying drawings. The examples use the single-nozzle combustor widely used in the early stage of thrust chamber development for illustration, and the method is also suitable for multi-nozzle combustor working conditions.

The device used to implement this measurement method mainly includes: a head 1 , a body outer sleeve 2 , a body inner liner 3 , and a tail nozzle part 4 .

The whole design process is arranged as follows:

1. Determine the number of outer sleeves 2 according to the range and number of inner diameters that need to be changed. On the one hand, it is necessary to ensure that the outer sleeve 2 occupies a certain amount of the material quality of the overall combustion chamber body, otherwise the cost savings will not be obvious; on the other hand, it must be ensured that the thickness of the inner lining 3 cannot be too thin, otherwise the stiffness of the inner lining 3 will be too low , and the combustion chamber sealing is difficult to guarantee.

2. Using thermal analysis and calculation, check and check the sealing parts at both ends of the lining 3 of each thickness. In the calculation, it is assumed that the inner and outer jackets are integrated, and the test time required for unsteady calculations is calculated. If it is found that the temperature in the sealing area exceeds the allowable temperature of the sealing material, the thickness of the lining must be increased to achieve the reliability of thermal protection.

3. Determine the size of the inner diameter of the outer sleeve. First, design and process the outer sleeve. The outer diameter of the inner lining assembled with it must be matched with it. The gap distance between 0.02-0.08mm can meet the test needs. And because the gap between the outer sleeve and the inner sleeve is small, the inner lining is heated and fits the outer sleeve during the test, and the heat is introduced into the outer sleeve, which can ensure the reliability of thermal protection.

The installation process of the combustion chamber is as follows: first, the outer sleeve and the inner bushing are installed together, and then the head and the nozzle are installed together to complete.

Claims (2)

1. A design method of a low-cost variable internal diameter combustion chamber, the design steps comprising: (a) designing the head nozzle and injector structure; (b) designing the nozzle size structure; (c) designing the body structure; The feature is that the combustion chamber adopts a heat-capacitating structure, and the material is made of pure copper with high thermal conductivity. The body is divided into two parts: the inner bushing and the outer sleeve; There are shoulders A and B at the end to strengthen the axial positioning of the inner liner; the two ends of the inner liner are respectively provided with shoulders C for placing sealing parts, so that the two ends of the combustion chamber body The end forms a seal; an outer sleeve is matched with multiple inner bushings, and the gap between the outer diameter of the inner bushing and the inner diameter of the outer sleeve is 0.02-0.08mm; when designing the body, first use thermal analysis calculations, for each Check and check the sealing parts at both ends of the thick inner bushing. If the temperature of the sealing part is found to exceed the allowable temperature of the sealing material, increase the thickness of the inner bushing; obtain the size and number of the outer sleeve according to the change of the inner diameter of the inner bushing. 2. The combustion chamber designed by the low-cost variable inner diameter combustion chamber design method of claim 1, characterized in that: the same outer sleeve is combined with multiple inner bushings with different inner diameters respectively.

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