CN-115112344-B - Working method of low total temperature state of thermal jet experiment device for shock tunnel

CN115112344BCN 115112344 BCN115112344 BCN 115112344BCN-115112344-B

Abstract

The invention provides a working method of a low total temperature state of a thermal jet experiment device for a shock tunnel, which utilizes the principles of stable combustion limit, ignition limit and high temperature ablation limit in the combustion process to determine an optimal ignition area of hydrogen and air combustion equivalent ratio, combines the operation time sequence of the thermal jet experiment device, adjusts the hydrogen and air combustion equivalent ratio to ignite under the working condition of the optimal ignition area, ensures that a combustion chamber stably burns under the high total temperature state, and reduces the hydrogen and air combustion equivalent ratio in the range of a lean oil ignition area so as to ensure that the combustion chamber continuously stably burns under the low total temperature state. The hydrogen and the air in the combustion chamber are firstly ignited under the working condition of large equivalent ratio and are stably combusted under the high total temperature state, then the flow of the hydrogen and the air is respectively and accurately regulated to the working condition of small equivalent ratio through the electronic pressure reducing valve, the stable combustion is kept under the low total temperature state, and the problem that the thermal jet experimental device cannot work under the low total temperature state is solved.

Inventors

LI LONG
WU SONG
YAO WEI
ZHAO WEI

Assignees

中国科学院力学研究所
中国科学院力学研究所

Dates

Publication Date: 20260421
Application Date: 20220607
Priority Date: 20220607

Claims (8)

1. A method of operating a thermal jet experiment device for a shock tunnel at low total temperature, comprising: 1) Determining an optimal ignition area of a hydrogen and air combustion equivalence ratio by utilizing the principles of a stable combustion limit, an ignition limit and a high-temperature ablation limit in a combustion process, wherein the equivalence ratio is the ratio of the air quantity required by a complete combustion theory to the air quantity actually supplied during fuel combustion; The optimal ignition region is a lean ignition region between a lean flame holding limit and a lean high temperature limit that does not include a high temperature ablation region; 2) By combining with the operation time sequence of the hot jet experiment device, the combustion equivalent ratio of the hydrogen to the air is adjusted to be ignited under the working condition of an optimal ignition area by controlling the gas flow of the hydrogen and the air entering the combustion chamber (30), and the combustion chamber (30) is stably combusted under the high total temperature state; 3) The flow rates of the hydrogen and the air are respectively and accurately regulated by the electronic pressure reducing valve, the combustion equivalent ratio of the hydrogen and the air is reduced in the range of the lean oil ignition area, and the total temperature of the combustion chamber (30) is reduced, so that the combustion chamber (30) continues to burn stably in a low total temperature state.
2. A method of operating a thermal jet experiment device for a shock tunnel at low total temperature as claimed in claim 1, wherein, The optimal ignition region is an ignition region between a lean ignition limit and a lean high temperature limit.
3. A method of operating a thermal jet experiment device for a shock tunnel at low total temperature as claimed in claim 1, wherein, Reducing the hydrogen to air combustion equivalence ratio in step 3) to within the flame holding region between the lean flame holding limit and the lean ignition limit.
4. A method of operating a thermal jet experiment device for a shock tunnel in a low total temperature regime as claimed in claim 1, further comprising: Before the step 2), an air electromagnetic stop valve (21) is opened to supply air to the combustion chamber, then a spark plug is opened to continuously pulse and ignite, and a hydrogen valve is opened.
5. A method of operating a thermal jet experiment device for a shock tunnel in a low total temperature regime as claimed in claim 1, further comprising: after step 2), the hydrogen and air are in stable combustion condition, and the spark plug is closed.
6. A method of operating a thermal jet experiment device for a shock tunnel in a low total temperature regime as claimed in claim 1, further comprising: the closing process of the thermal jet experiment device comprises the steps of firstly closing a hydrogen electromagnetic stop valve (8), cutting off hydrogen supply, closing an air electromagnetic stop valve (21), cutting off air supply, changing the air flow to 0 after the hydrogen flow becomes 0 and flame in a combustion chamber is extinguished, then closing all the stop valves on the hydrogen and air pipelines, stopping control by an industrial personal computer (45), and ending the experiment.
7. A method of operating a thermal jet experiment apparatus for a shock tunnel in a low total temperature state according to claim 2 or 3, wherein, in the method of operation, The lean flame holding limit was 0.09, the lean ignition limit was 0.19, and the lean high temperature limit was 0.4.
8. A method of operating a thermal jet experiment apparatus for a shock tunnel according to any one of claims 1 to 6, wherein the next step is performed after a time at which each step in the method is not fully equal.

Description

Working method of low total temperature state of thermal jet experiment device for shock tunnel Technical Field The invention relates to the field of shock tunnels, in particular to a working method of a thermal jet experiment device for a shock tunnel in a low total temperature state, which adopts a mode of mixed combustion of hydrogen and air, the principle of stable combustion limit, ignition limit and high-temperature ablation limit in the combustion process is utilized, and the operation time sequence is combined, so that the difficulty that the thermal jet experimental device cannot work in a low total temperature state is solved. Background In the flight of hypersonic aircrafts, the coupling of the inner flow and the outer flow of an engine and jet flow generated for realizing attitude and orbit control can generate strong shock wave/shock wave interference, shock wave/boundary layer interference, separation and reattachment and other large-area unsteady and unstable flow fields, so that the aerodynamic force and aerodynamic heat of the aircrafts are greatly disturbed. And the aerodynamic heat ground test is mainly performed in shock tunnels of millisecond magnitude. The difficulties of generating a transient stable hot jet air source, synchronizing time sequences in millisecond magnitude, a small-scale model and the like result in great difficulty of a shock tunnel hot jet experiment. Based on the above, we propose a novel shock tunnel thermal jet test device and method (application number: 202110529968.3 is used for thermal jet test device of shock tunnel, application number: 202110529954.1 is used for thermal jet test method of shock tunnel). The thermal jet experiment device adopts the combination combustion of hydrogen and air to realize the ejection of high-temperature gas from a wind tunnel model at supersonic speed. The thermal jet comprehensive experiment device fully considers safety, reliability, stability and subsequent expansibility. Aiming at the thermal jet flow experimental device, in order to ensure safe and smooth experimental process (no explosion, no flameout and no pulse vibration), the following 3 factors need to be comprehensively considered: 1. The combustion chamber is ignited stably; 2. after ignition is completed, stable combustion can be performed in the combustion chamber; 3. ensuring that the combustion chamber is not burnt in the ignition combustion process. Through multiple experimental tests, the hot jet experimental device is found that the device can only work in the equivalent ratio range of (f 2, f 3), and the equivalent ratio is lower than f2, so that flame cannot be ignited, the limit temperature range of the device is (898K, 1427K), and it is very difficult to obtain jet gas with lower temperature by using the jet experimental device. In practical experiment work, a great amount of hot gas jet is required to be generated at the temperature of 650K, and the problem that the hot gas jet experiment device cannot be ignited and started to work in a low total temperature state exists. Disclosure of Invention The invention provides a working method of a thermal jet experiment device for a shock tunnel in a low total temperature state, which adopts a mode of mixed combustion of hydrogen and air, utilizes the principles of stable combustion limit, ignition limit and high-temperature ablation limit in the combustion process, and solves the problem that the thermal jet experiment device cannot work in the low total temperature state by combining operation time sequence. A method of operating a thermal jet experiment device for a shock tunnel at low total temperature conditions, comprising: 1) Determining an optimal ignition area of a hydrogen and air combustion equivalence ratio by utilizing the principles of a stable combustion limit, an ignition limit and a high-temperature ablation limit in a combustion process, wherein the equivalence ratio refers to the ratio of air quantity required by a complete combustion theory to the air quantity actually supplied when fuel is combusted; 2) By combining with the operation time sequence of the thermal jet experiment device, the combustion equivalence ratio of the hydrogen and the air is adjusted to ignite under the working condition of the optimal ignition area by controlling the gas flow of the hydrogen and the air entering the combustion chamber, and the combustion chamber is stably combusted under the high total temperature state; 3) The flow rates of the hydrogen and the air are respectively and accurately regulated by the electronic pressure reducing valve, the combustion equivalent ratio of the hydrogen and the air is reduced in the range of the lean oil ignition area, and the total temperature of the combustion chamber starts to be reduced, so that the combustion chamber continues to stably burn in a low total temperature state. As a preferred embodiment of the invention, the optimal ignition region in step 1) is a lean i