Vacuum thrust in-situ calibration device

Abstract

The invention provides a thrust in-situ calibration device for a rocket engine high-altitude simulation test, which is a comparison type calibration method for generating calibration force based on a standard force sensor matched with a loading force source, and is characterized in that the standard force sensor is arranged outside a vacuum test cabin; meanwhile, a dynamic sealing form with extremely low friction force is adopted between the calibration mechanism and the vacuum test cabin, so that the high vacuum degree of the test environment is met, the calibration precision is basically not influenced, and the thrust in-situ calibration problem in the high vacuum environment is solved; the maximum loading force can reach 10 KN, the calibration precision is superior to 0.07%, and the thrust measurement precision of the high-altitude simulation test of the engine is improved.

Description

Technical Field

[0001] The invention relates to the field of rocket engine testing, in particular to a test structure used for thrust calibration of a rocket engine high-altitude simulation test. Background Art

[0002] In the process of developing aerospace attitude and orbit control power systems, it is necessary to develop relevant test equipment to comprehensively and accurately obtain the high-altitude working characteristics of the engine. Among them, the measurement of engine thrust characteristics in high-altitude environments is an important purpose of engine testing. As an important part of thrust measurement, thrust in-situ calibration is mainly aimed at reducing the measurement uncertainty introduced by the preload system and pipelines, and improving the accuracy of thrust measurement.

[0003] At present, the domestic field of vacuum thrust calibration technology has achieved certain results, and a vacuum thrust calibration implementation plan has been formed for engines of various models and thrusts. Since the mechanical properties of the force sensor and force transmission mechanism will change after a long period of vacuum during the high-altitude simulation test of the engine, the structural differences of the thrust calibration implementation plans of various models are mainly reflected in the arrangement of the three key links of force measurement, force transmission and force loading of the test device.

[0004] For small-sized and small-thrust engines, thrust loading, thrust measurement and force transmission mechanisms are mainly arranged in a vacuum test chamber; this effectively reduces the impact of characteristic changes of sensors and force transmission mechanisms in a vacuum environment on the thrust calibration system. However, since the upper-level measurement unit does not have the ability to calibrate force sensors in a vacuum, it is impossible to eliminate the impact of using standard force sensors calibrated at normal pressure in a vacuum environment.

[0005] For large thrust engines, the main feature is to place the thrust measurement mechanism in the test cabin and arrange the thrust loading device outside the test cabin. The calibration mode commonly used in existing ground tests is still used, and the thrust calibration characteristics under ground conditions are used to replace the vacuum thrust characteristics. Summary of the invention

[0006] The purpose of the present invention is to provide a technical method for improving the in-situ calibration accuracy of the vacuum thrust of an aerospace engine in the field of high-altitude simulation tests.

[0007] To achieve the above object, the solution of the present invention is:

[0008] The vacuum thrust in-situ calibration device described in the present invention comprises a vacuum test chamber, a thrust calibration base, a thrust loading mechanism, and a force measuring mechanism.

[0010] The vacuum test chamber is an environmental chamber for high-altitude simulation test of engine characteristics, connected to vacuum pumping equipment. The thrust calibration base is the engine thrust calibration force base, the output force of the thrust loading mechanism is used to simulate the engine thrust for calibration test, including a loading force source, a standard force sensor, a reversing frame, and a calibration sealing structure, wherein the loading force source, the standard force sensor and the reversing frame are located outside the vacuum test chamber, and the rest are located inside the vacuum test chamber. The standard force sensor is used to measure the force applied by the loading force source to the engine, the reversing frame is used to convert the direction of the output force of the thrust loading mechanism and apply it to the engine, and keep its applied force consistent with the three mechanical elements of the real thrust generated by the engine thrust chamber, the calibration sealing structure is the interface part between the thrust loading mechanism and the vacuum test chamber, used to make the vacuum test chamber airtight when performing the thrust calibration test, the thrust loading mechanism is installed on the thrust calibration base, the force measuring mechanism includes a thrust frame and a thrust measurement sensor, the thrust frame is the engine thrust measurement force base, and the thrust measurement sensor is used to measure the loading force applied by the engine to the thrust frame.

[0011] The force measuring mechanism is installed in the vacuum test chamber, the thrust calibration base is located outside the vacuum test chamber, and the loading force source, standard force sensor, and commutation frame in the thrust measurement loading mechanism are located outside the vacuum test chamber.

[0012] The seal of the calibration sealing structure adopts a low-friction toothed sliding ring combined seal with sealing function for reciprocating shaft, which can not only meet the vacuum degree requirement of the vacuum sealing chamber in the calibration test, but also maintain extremely low friction with the vacuum test chamber during the calibration reciprocating stroke, so that the influence of the friction force of the vacuum test chamber on the calibration loading mechanism on the calibration accuracy can be ignored.

[0013] The calibration seal structure includes a calibration rod, an O-ring, a hatch flange, a cabin neck sleeve, a toothed sliding ring type combined seal, and a cabin neck flange. The two ends of the calibration rod are respectively connected to the reversing frame and the engine, and are used to transmit the output force of the power source to the engine. The cabin neck sleeve is embedded in the cabin neck flange with an interference fit and is sealed with the cabin neck flange by an O-ring. The cabin neck sleeve is coaxially installed with the calibration rod, and a toothed sliding ring type combined seal is used between the calibration rod and the calibration rod for axial reciprocating motion sealing, and the friction force is extremely low, and the influence on the calibration accuracy can be ignored. The end face of the cabin neck sleeve is drilled with a threaded hole for easy maintenance and replacement. The hatch flange and the cabin neck flange are sealed with an O-ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural diagram of a test device used for thrust calibration in high-altitude simulation tests of rocket engines.

[0015] Figure 2It is the calibration seal structure form in the above-mentioned thrust calibration test device.

[0016] Figure 1 1-reversing frame; 2-standard force sensor; 3-loading force source; 4-thrust calibration base; 5-calibration sealing structure; 6-vacuum test chamber; 7-thrust measurement sensor; 8-thrust frame; 9-engine

[0017] Figure 2 Among them, 1-calibration pull rod; 2, 4, 6-O-rings; 3-hatch cover flange; 5-cabin neck sleeve; 7-toothed sliding ring combined seal; 8-cabin neck flange. DETAILED DESCRIPTION

[0018] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0019] like Figure 1 As shown, a test device for thrust calibration of a rocket engine high-altitude simulation test is characterized in that it includes a vacuum test chamber 6, a thrust calibration base 4, a thrust loading mechanism, and a force measuring mechanism. The vacuum test chamber 6 is an environmental chamber for high-altitude simulation tests of engine characteristics, and is connected to a vacuum pumping device. Specifically, the vacuum pumping device includes a vacuum pump and an exhaust ejection device. The thrust calibration base 4 is a force-bearing base for engine thrust calibration. The output force of the thrust loading mechanism is used to simulate the engine thrust for calibration tests and is installed on the thrust calibration base 4. It includes a loading force source 3, a standard force sensor 2, a reversing frame 1, and a calibration sealing structure 5. Specifically, the loading force source 3 can be a hydraulic cylinder or an electric push rod, and the standard force sensor 2 uses a compressive strain sensor to measure the force transmitted from the loading force source 3 to the engine 9 through the reversing frame 1. The reversing frame 1 is used to convert the thrust output by the loading force source 3 into a pulling force applied to the engine 9. And its pulling force is consistent with the three mechanical elements of the real thrust generated by the engine thrust chamber; as described in the background technology, one of the error sources in the current common vacuum thrust calibration scheme is the inconsistency between the calibration and use environment of the standard force sensor 2. At present, there is no vacuum calibration condition for the standard force sensor 2 in the upper level measurement unit. Therefore, the loading force source 3, the standard force sensor 2, and the reversing frame 1 are arranged outside the vacuum test chamber 6 to keep the calibration and use environment of the standard force sensor 2 consistent to eliminate the influence of the above error, and the rest of the thrust loading mechanism is located in the vacuum test chamber 6. The force measuring mechanism is located in the vacuum test chamber 6, including a thrust frame 8 and a thrust measurement sensor 7. The thrust frame 8 is the force-bearing basis for engine thrust measurement, and the thrust measurement sensor is used to measure the loading force applied by the engine to the thrust frame.

[0012] like Figure 1As shown in FIG. 1 , the calibration sealing structure 5 is the interface between the thrust loading mechanism and the vacuum test chamber 6 and is used to make the vacuum test chamber 6 airtight during the thrust calibration test. Figure 2 As shown in the figure: in the vacuum thrust calibration test, the calibration sealing structure ensures the vacuum degree of the vacuum sealing cabin during the test, and also causes friction between the thrust loading mechanism and the vacuum test cabin, making it a source of error affecting the calibration accuracy; the calibration sealing structure includes a calibration rod 1, O-rings 2, 4, 6, a hatch flange 3, a cabin neck sleeve 5, a toothed sliding ring type combined seal 7, and a cabin neck flange 8. The two ends of the calibration rod 1 are respectively connected to Figure 1 The reversing frame 1 shown is connected to the engine 9 and is used to transmit the output force of the power source to the engine. The cabin neck sleeve 5 is embedded in the cabin neck flange 8 with an interference fit and is sealed with the cabin neck flange 8 by an O-ring. The cabin neck sleeve 5 is coaxially installed with the calibration rod 1 and a toothed sliding ring type combined seal is used to seal the axial reciprocating motion with the calibration rod 1. It can maintain extremely low friction with the vacuum test chamber during the calibration reciprocating stroke, which can meet the vacuum degree requirements and make the influence of friction on the calibration accuracy negligible. A threaded hole is drilled on the end face of the cabin neck sleeve 5 for easy maintenance and replacement. The cabin cover flange 3 and the cabin neck flange 8 are sealed with an O-ring.

Claims

1. The vacuum thrust in-situ calibration device includes a vacuum test chamber, a thrust calibration foundation, a thrust loading mechanism, and a force measuring mechanism. The thrust loading mechanism includes a loading force source, a standard force sensor, a reversing frame, and a calibration sealing structure, wherein the loading force source, the standard force sensor, and the reversing frame are located outside the vacuum test chamber, and the rest are located inside the vacuum test chamber. The calibration sealing structure is the interface between the thrust loading mechanism and the vacuum test chamber, and the thrust loading mechanism is installed on the thrust calibration foundation. The force measuring mechanism includes a thrust frame and a thrust measurement sensor.

2. The calibration seal structure includes a calibration rod, an O-ring, a hatch flange, a neck sleeve, a toothed sliding ring combined seal, and a neck flange. The two ends of the calibration rod are connected to the reversing frame and the engine respectively. The neck sleeve is embedded in the neck flange with an interference fit and is sealed with the neck flange by an O-ring. The neck sleeve is coaxially installed with the calibration rod and a toothed sliding ring combined seal is used to seal the axial reciprocating motion with the calibration rod. The end face of the neck sleeve is drilled with threaded holes for easy maintenance and replacement. The hatch flange and the neck flange are sealed with an O-ring.

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