Annular electrostatic sensor for measuring tail flame speed of engine

Abstract

The invention provides a circular electrostatic sensor for measuring the tail flame speed of an engine. Comprising an electrode, an insulating ring, an insulating shell, a shielding layer and a rear cover, the insulating ring is arranged between the two electrodes to prevent mutual interference of charge signals; the sensing part of the electrostatic sensor selects two insulating rings to clamp one electrode; the insulating shell is a shielding firmware and is arranged between the electrostatic sensor and the electrode to prevent interference of environmental charge noise on the electrode; the shielding layer is sleeved outside the insulating shell; and the rear cover is a final sealing part of the electrostatic sensor. The electrostatic sensor is a universal and conventional electrostatic sensor, and has better universality and compatibility; high temperature resistance and ablation resistance are realized; and the electrostatic sensor is made of a high-strength and wear-resistant material, so that the stability and the reliability of the electrostatic sensor in long-term use are ensured.

Description

Technical Field

[0001] This invention relates to the field of electrostatic sensor technology, and specifically to a ring-shaped electrostatic sensor for measuring the velocity of engine exhaust flame. Background Technology

[0002] Solid rocket motor exhaust plumes are a common test subject in the field of solid rocket motor technology, characterized by ultra-high temperature, ultra-high speed, and ablation properties.

[0003] An electrostatic sensor is a sensor used to detect the electric field generated by charged objects or particles. Its basic structure includes sensing electrodes, a shielding layer, signal amplification and processing circuitry, grounding, and encapsulation. The sensing electrodes, typically made of conductive materials, can be in shapes such as plates or cylinders. Their main function is to capture the electrostatic field generated when charged particles pass by, outputting a signal through the induced charge on the electrodes. To avoid external interference and the influence of other electromagnetic fields, the sensor is generally equipped with a shielding layer made of conductive materials such as metal mesh or metal foil, ensuring signal purity. The grounding section stabilizes the electric field, preventing signal drift and interference, allowing the sensor to more accurately detect the induced signal of charged particles. Finally, the encapsulation structure, made of plastic or metal, protects the internal electrodes and circuitry. Its design considers protection, waterproofing, and dustproofing to ensure the sensor functions properly in various environments. When a charged particle or object passes near the sensor, the charge on the sensing electrodes redistributes, generating an induced current, which is amplified and processed before being output as a signal. The amplitude and frequency of this signal are related to the velocity, number, and charge of the charged particles. Electrostatic sensing technology is well-suited for detecting the velocity of solid-state exhaust plumes.

[0004] Traditional electrostatic sensors are primarily designed for industrial applications, focusing on waterproofing and dustproofing while neglecting high-temperature resistance and ablation resistance. Therefore, they are unsuitable for solid-generated exhaust flame environments. There are no universally compatible models of electrostatic sensors; each sensor is custom-designed based on specific field testing conditions. Consequently, the structural parameters of each sensor are inconsistent, and no electrostatic sensors have been found specifically designed for solid-generated exhaust flame environments. In solid-generated exhaust flames, temperatures can reach as high as 2000K, making it difficult for traditional electrostatic sensors to withstand such temperatures. Furthermore, the presence of ablation components in solid-generated exhaust flames makes traditional electrostatic sensors ill-suited for ablation resistance. Additionally, the generally fixed dimensions of the testing apparatus mean that traditional electrostatic sensors cannot be dimensionally adapted to solid-generated exhaust flame testing. Summary of the Invention

[0005] Based on the above-mentioned technical problems, this invention proposes a ring-shaped electrostatic sensor for measuring engine exhaust flame velocity, in order to solve three problems existing in electrostatic sensors in solid engine exhaust flame velocity measurement: 1) Solving the problem of high temperature resistance of electrostatic sensors: In solid engine exhaust flames, the exhaust flame temperature is as high as 2000K, and traditional electrostatic sensors are difficult to adapt to the exhaust flame temperature; 2) Solving the problem of ablation resistance of electrostatic sensors: There are ablation components in solid engine exhaust flames, and traditional electrostatic sensors are difficult to resist ablation; 3) Solving the problem of adaptability to the test environment: The size of the test apparatus is generally fixed, and traditional electrostatic sensors cannot be adapted to the size of solid engine exhaust flame tests.

[0006] To address the aforementioned technical problems, one objective of this invention is to provide a ring-shaped electrostatic sensor for measuring engine exhaust velocity, comprising electrodes, an insulating ring, an insulating housing, a shielding layer, and a rear cover. The electrodes are circular in shape to enhance the induced charge signal; The insulating ring is placed between the two electrodes to prevent mutual interference of charge signals. The sensing part of the electrostatic sensor uses two insulating rings sandwiching an electrode, with the insulating rings and the electrode stacked in contact. The insulating shell is a shielding fastener. An insulating shell is fitted over the outside of the insulating ring and the electrode to prevent environmental charge noise from interfering with the electrode. The insulating shell is placed in contact with the insulating ring and the electrode. The shielding layer is placed on top of the insulating shell, with the insulating shell and the shielding layer in contact. The rear cover is the final sealing component of the electrostatic sensor, and it is connected to the rear of the shielding layer by a spiral pattern.

[0007] Furthermore, the electrode is made of copper, which has excellent electrical conductivity.

[0008] Furthermore, the insulating ring is made of polytetrafluoroethylene, a material with excellent insulating properties.

[0009] Furthermore, the insulating ring material is the same as the insulating housing material to prevent charge transfer from occurring during contact between the electrostatic sensor housing and the electrodes. Furthermore, the shielding layer is made of stainless steel, which has good conductivity and high temperature resistance.

[0010] Furthermore, the rear of the shielding layer's housing is designed in a hexagonal shape, providing good connectivity with the tester's rear cover and allowing it to be embedded inside the tester.

[0011] Furthermore, the back cover is made of the same material as the housing, namely stainless steel.

[0012] The above-described one or more technical solutions of the present invention have at least one or more of the following technical effects: This invention has higher high temperature resistance. Through the selection of shielding layer material and sensor structure design, it can ensure that the electrostatic sensor can withstand the high temperature of 2000K of the tail flame during the measurement of solid tail flame velocity, thus avoiding the electrostatic sensor from burning out due to high temperature.

[0013] This invention has better resistance to ablation. Through the selection of shielding layer material and sensor structure design, it can ensure that the electrostatic sensor can withstand the erosion and ablation of the tail flame during the measurement of solid tail flame velocity.

[0014] This invention has better adaptability. Designed for the field of solid rocket motor exhaust velocity testing, it takes into account the common size of general test equipment and designs a more universal and conventional electrostatic sensor, which has better versatility and compatibility and reduces the redesign cost caused by unsuitable sensor size.

[0015] This invention offers higher measurement accuracy. It is designed for conventional solid rocket motor test equipment and features a more suitable electrostatic sensor, reducing measurement errors caused by sensor size mismatch.

[0016] This invention offers enhanced durability by employing high-strength, wear-resistant materials to manufacture the electrostatic sensor, ensuring its stability and reliability during long-term use. Attached Figure Description

[0017] Figure 1 Overall structure diagram of the electrostatic sensor; Figure 2 : Working principle diagram of an electrostatic sensor; Figure 3 Schematic diagram of the electrode structure of an electrostatic sensor; Figure 4 Schematic diagram of the insulating ring structure of an electrostatic sensor; Figure 5 Diagram of the arrangement of electrodes and insulating rings in an electrostatic sensor; Figure 6 Diagram of the insulating housing of an electrostatic sensor; Figure 7 Assembly diagram of electrostatic sensor electrodes and insulating housing; Figure 8 Diagram of the shielding layer housing for an electrostatic sensor; Figure 9 Image of the back cover of the electrostatic sensor; Figure 10 Photo of an electrostatic sensor. Detailed Implementation

[0018] This invention addresses the velocity measurement of solid rocket motor exhaust plumes, primarily focusing on the design of electrostatic sensors, including electrode design, insulating ring design, insulating shell design, shielding layer design, and rear cover design. The overall design diagram of the electrostatic sensor is shown below. Figure 1 As shown.

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments obtained. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0020] The principle of this invention's electrostatic sensor for measuring exhaust velocity is as follows: Figure 2 As shown, the complex chemical processes in a flame produce numerous cations, anions, and intermediate products, all of which are conductive. Electrostatic probes were used to measure the potential and ion current distribution in different regions of the flame at different heights and horizontal directions. The measurement results show that both the absolute value of the voltage and the current decrease with increasing vertical height, indicating that the concentration of cations and anions in the flame gradually decreases with increasing flame height. The current change is not significant in the horizontal direction; the overall trend is that the measured current value decreases with increasing horizontal distance, meaning that the ion concentration in the flame decreases with increasing horizontal distance.

[0021] In addition, unburned carbon particles and other microparticles in the jet flame also carry static charges. As these particles flow in the airflow, they further accumulate charges through collisions with other charged particles and friction with the airflow. This charging phenomenon is random and complex, but it is more pronounced under the high-temperature combustion conditions of the jet flame, making it suitable for flow velocity detection using electrostatic sensing technology.

[0022] By using electrostatic sensors to sense charged particles in a flame, induced charge signals can be obtained, and flame flow velocity information can be extracted from them, thereby analyzing the flame flow field characteristics and combustion dynamics.

[0023] This invention relates to an electrostatic sensor design, which comprises electrodes, an insulating ring, an insulating housing, a shielding layer, and a back cover. For example... Figure 1 As shown, a cylindrical structure made of high-temperature resistant insulating ceramic is used to protect the sensor from the direct effects of high-temperature flames and fumes.

[0024] Ceramics possess excellent high-temperature resistance and good insulation properties, ensuring they do not affect the acquisition and transmission of electrostatic signals. The cylindrical structure surrounding the engine nozzle effectively withstands high temperatures without obstructing the normal combustion of the engine's exhaust flame. The sensor array consists of multiple annular electrodes axially distributed on the outer wall of the ceramic cylinder, ensuring accurate detection of velocity changes across different flame heights. To further enhance resistance to high-temperature interference, a stainless steel shield is added to the outside of the ceramic tube. Stainless steel's excellent high-temperature stability and electromagnetic interference resistance shield external interference signals, thereby improving measurement stability and accuracy. The non-contact annular sensor structure design helps prevent direct flame contact with the sensor electrodes, preventing damage to the electrodes and interference with the acquired signals caused by high temperatures and ion flows. The following is a detailed design of the electrostatic sensor, including: electrode design, insulating ring design, insulating shell design, shielding layer design, and rear cover design.

[0025] The electrode design, based on the dimensions of conventional testing equipment, employs a 28mm diameter, ring-shaped electrode. To enhance the induced charge signal, copper, a material with excellent conductivity, is selected. The three-dimensional structural model of the electrostatic sensor electrode is shown below. Figure 2 As shown.

[0026] The insulating ring design requires isolation between the two electrodes to prevent interference between charge signals. Polytetrafluoroethylene (PTFE), with its excellent insulating properties, is chosen as the material for the insulating ring. The three-dimensional structural model of the insulating ring is shown below. Figure 3 As shown.

[0027] The electrostatic sensor's sensing section uses a configuration of two insulating rings sandwiching one electrode, resulting in a total of five electrodes. The three-dimensional arrangement of the electrodes and insulating rings is shown in the image below. Figure 4 As shown. The insulating shell design of the electrostatic sensor serves two purposes: firstly, it supports the electrodes and insulating ring, preventing direct contact between the electrodes and the flame; secondly, it acts as a shield, preventing interference from environmental charge noise. Therefore, the shell material is generally chosen to be metal. To prevent charge transfer during contact between the shell and the electrodes, an insulating shell is installed between them. The insulating shell is made of the same material as the insulating ring, namely polytetrafluoroethylene (PTFE). A model of the electrostatic sensor's insulating shell is shown below. Figure 5 As shown.

[0028] The installation effect between the electrode and the insulating housing is as follows: Figure 6 As shown.

[0029] The shielding layer design involves an outer shielding layer over an insulating shell. This shielding layer should possess excellent conductivity and high-temperature resistance; therefore, stainless steel is chosen as the shielding layer material. To ensure good connectivity with the test chamber's rear cover, the rear of the shielding layer shell is designed in a hexagonal shape, embedding itself inside the test chamber. A model of the electrostatic sensor shielding layer shell is shown below. Figure 7 As shown.

[0030] The rear cover design: The final sealing component of the electrostatic sensor is the rear cover, which is made of the same material as the housing, stainless steel. A 3D model of the electrostatic sensor rear cover is shown below. Figure 8 As shown. The thickness is 20mm, the diameter is 175mm, and the diameter of the central through hole is 28mm.

[0031] Physical fabrication: The electrostatic sensor is fabricated according to the instructions. The actual electrostatic sensor is as follows. Figure 9 As shown.

[0032] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations to the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

[0033] The present invention provides an electrostatic sensor for measuring the exhaust velocity of a solid rocket engine. Through testing, the stability, reliability, high temperature resistance, and ablation resistance of the sensor have been verified.

Claims

1. A circular ring shaped electrostatic sensor for engine plume velocity measurement, characterized by: The electrode, the insulating ring, the insulating shell, the shielding layer and the back cover are included, The electrode is circular, which enhances the induced charge signal; The insulating ring is arranged between the two electrodes to prevent the mutual interference of the charge signals; The static sensor sensing part selects two insulating rings and one electrode, and the insulating rings are in contact with the electrode; The insulating shell is a shielding shell, which is arranged outside the insulating ring and the electrode to prevent the environmental charge noise from interfering with the electrode, and the insulating shell is in contact with the insulating ring and the electrode; The shielding layer is arranged outside the insulating shell, and the insulating shell is in contact with the shielding layer; The back cover is the last closed part of the static sensor, which is connected with the back part of the shielding layer through a spiral thread.

2. The annular electrostatic sensor for engine plume velocity measurement according to claim 1, characterized in that: The electrode is made of copper material with excellent conductive performance.

3. The annular electrostatic sensor for engine plume velocity measurement according to claim 1, characterized in that: The insulating ring is made of polytetrafluoroethylene material with excellent insulating performance.

4. The annular electrostatic sensor for engine plume velocity measurement according to claim 1, characterized in that: The material of the insulating ring is the same as that of the insulating shell, which avoids the charge transfer between the static sensor shell and the electrode.

5. The annular electrostatic sensor for engine plume velocity measurement according to claim 1, characterized in that: The shielding layer is made of stainless steel material with good conductive performance and high temperature resistance.

6. The annular electrostatic sensor for engine plume velocity measurement according to claim 5, characterized in that: The back part of the shielding layer is designed as a hexagonal type, which has good connectivity with the back cover of the tester and is embedded in the tester.

7. The annular electrostatic sensor for engine plume velocity measurement according to claim 1, characterized in that: The material of the back cover is the same as that of the shell, which is made of stainless steel material.

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