CN105701329A - Method for measuring temperature of combustion chamber of hydrogen fluoride laser by utilizing trace hydrogen process - Google Patents

Abstract

The invention relates to a method for measuring the temperature of a combustion chamber of a hydrogen fluoride laser by utilizing a trace hydrogen process. The method comprises the steps of based on a pneumodynamics technology and a spontaneous radiation fluorescence spectrum technology, measuring the temperature of an optical cavity by using a hydrogen fluoride fluorescence spectrum at first and then inversely deducing the temperature of the combustion chamber according to pneumatics. The method is mainly applied to the technical field of hydrogen fluoride chemical laser test diagnosis and can measure the temperature of the combustion chamber of the hydrogen fluoride laser by utilizing an optical process under the condition that the combustion chamber is not provided with an observation window. According to the method, by utilizing a trace hydrogen injection technology, the influence of heat release in a chemical reaction of hydrogen and fluorine atoms on the temperature of main airflow flowing out of the combustion chamber is reduced. The method has the characteristics of simplicity, convenience, intuitiveness, accuracy, non-invasiveness and the like.

Description

A kind of method utilizing trace hydrogen method to measure hydrogen fluoride laser chamber temperature

Technical field

The present invention relates to the measurement diagnostic method of a kind of hydrogen fluoride chemical laser。At light intracavity, utilize trace hydrogen method for implanting, measure combustor air-flow optical cavity gas flow temperature T after nozzle expansion_cav, then can obtain chamber temperature T according to counter the pushing away of aerodynamics knowledge₀。The present invention utilizes non-invasive optical measurement technology to obtain chamber temperature T when can be implemented in combustor without observation window₀。

Background technology

Since First chemical laser in 1964 comes out, the development of chemical laser can be rated as advances by leaps and bounds, speed is surprising, wherein especially ripe with the development of hydrogen fluoride chemical laser, U.S.'s Alph hydrogen fluoride chemical laser of continuous wave output power up to MW rank had once been once the synonym of laser weapon。

The main operating principle of hydrogen fluoride chemical laser is as follows:

(1) F atom is produced containing the pyrolysis in a combustion chamber of F compound, it is also possible to have a small amount of F₂Molecule, it addition, F atom is likely to compound and produces F in by the process of nozzle₂Molecule；

(2) H of F atom out and addition from nozzle₂Molecule reacts, and produces the HF molecule (representing with HF (v)) of vibration excited state, F+H₂→ HF (v)+H, the thermal discharge of this reaction is less (31.5kcal/mol), is referred to as cold reaction, and the vibrational quantum number of product HF molecule is the highest can arrive v=3；

(3) H atom produced again can with F₂There is cold reaction in molecule, produces the HF molecule (representing with HF (v)) of vibration excited state, H+F₂→ HF (v)+F, the caloric value of this reaction very big (98.0kcal/mol), it is referred to as thermal response, the vibrational quantum number of product HF molecule is the highest can arrive v=10；

(4) according to Einstein's stimulated radiation principle, there is resonance in vibration excited state molecule HF (v) in optical cavity, produces laser。

Owing to fluorine atom is produced by Nitrogen trifluoride pyrolysis in a combustion chamber, therefore the temperature of combustor directly determines the productivity of fluorine atom, in order to understand the operation conditions of hydrogen fluoride chemical laser in depth, it is necessary to chamber gas temperature T₀Measurement diagnosis。

The combustor of hydrogen fluoride chemical laser is typically all superhigh temperature operating, it is about about 2000K, exceed the measurement upper limit of general thermocouple, thermocouple may burn, and therefore conventional intrusive mood thermometry (i.e. thermocouple method) is not suitable for the temperature test of hydrogen fluoride chemical laser combustion room。

Optical means is owing to having Noninvasive, so being suitable for the test occasion of this superhigh temperature the most。But, the combustor of hydrogen fluoride chemical laser is typically all and seals operating, adds observation window relatively difficult, is not suitable for directly digging an observation window at combustor。It addition, chamber pressure is higher, being typically between 1～2 atmospheric pressure, the life-span of incandescnet particle is very short, and luminous intensity is also more weak, therefore comprehensively, directly opens an observation window in combustor position and utilizes luminescent spectrum measurement temperature to be unaccommodated。

The present invention just in this context, fully takes into account aerodynamic technique and F+H₂A kind of technology utilizing trace hydrogen method to measure hydrogen fluoride laser chamber temperature putting thermal property and design。The ultimate principle of this technology is as follows, first allow combustion chamber high temperature air-flow by entering optical cavity after nozzle expansion, the trace hydrogen being about primary air flow 0.01%～0.1% is injected in optical cavity entry position, hydrogen produces the HF (v) of vibration excited state with Fluorine atom, the chemiluminescence of light intracavity is collected by chamber mirror, shaking of HF (v) can be obtained and turn Transition Spectra, can measure according to this spectrum and obtain light intracavity gas flow temperature T_cav；Trace hydrogen owing to injecting is only small to the disturbance of primary air, so obtained light intracavity gas flow temperature T_cavThe downstream static temperature T after primary air is expanded by superonic flow nozzzle can be considered as equal to, measure chamber pressure P simultaneously₀With cavity pressure P, then estimate specific heat ratio γ, can be obtained by chamber pressure T finally according to aerodynamics formula₀。

Light cavity temperature is easy to use luminescence spectroscopy measurement, and the difference of HF (v) the vibrational state particle luminous intensity turning transition radiation of shaking can represent by equation below:

I_v,J=hc ω_v,JA_v,JN_v,J(1)

Wherein h is Planck constant, and c is the light velocity, ω_v,JFor transition wave number, A_v,JFor Einstein Spontaneous Emission Coefficients, N_v,JPopulation density for transition of shaking (v, J)。

Each rotating state population distribution of HF molecular vibration state meets rotation thermal balance distribution (Boltzmann distribution law), namelyWherein N_vFor the population density of vibrational state (v), g_v,JFor the degeneracy of transition of shaking (v, J), E_v,JBeing the rotational energy level of (v, J) state, k is Boltzmann constant, and T is gas temperature, Q_vFor rotational partition function。HF rotational partition function generally can be expressed as(1) formula of substitution, and are taken the logarithm in both sides, then can obtain equation below:

$\ln \left(\frac{I_{v,J}}{{\mathrm{\ω}}_{v,J}{A}_{v,J}{g}_{v,J}}\right)=-\frac{\mathrm{hc}{E}_{v,J}}{\mathrm{kT}}+\ln \left(\frac{h^2{c}^2{N}_v{B}_v}{\mathrm{kT}}\right)$

WillIt is abbreviated as Ln (I/wag), constant is substituted into and obtains hc/k=1.44, it is possible to willIt is labeled as 1.44F_u, equation below can be obtained:

$1.44F_u=-\mathrm{Ln}(I/\mathrm{wag})*T+T\ln \left(\frac{h^2{c}^2{N}_v{B}_v}{\mathrm{kT}}\right)---\left(3\right)$

It can be seen that Ln (I/wag) and 1.44F_uLinear, the negative of its slope is exactly the rotation temperature T of HF molecule_rot, i.e. light intracavity gas temperature T_cav。

According to aerodynamics knowledge, the superonic flow nozzzle upstream stagnation temperature T of hydrogen fluoride laser₀And there is following relation between the static temperature T of downstream:

$T_0=T{\left(\frac{P_0}{P}\right)}^{\frac{\mathrm{\γ}-1}{\mathrm{\γ}}}---\left(4\right)$

Wherein, the superonic flow nozzzle upstream stagnation temperature T of hydrogen fluoride laser₀It is the temperature of combustor。Consider upstream stagnation pressure P₀Compare use Pressure gauge with downstream static pressure P easily to measure, if being aware of the downstream static temperature T after primary air expands again, then (4) formula just can be utilized to obtain chamber temperature T₀。

But, although light intracavity gas temperature T_cavIt is readily available, but time the hydrogen fluoride chemical laser under general operating mode operates, light intracavity gas temperature T_cavBeing not equivalent to downstream static temperature T, this is on the one hand owing to the chemical reaction of fluorine atom and hydrogen molecule can release substantial amounts of heat, causes that the temperature of primary air raises；The thermal capacitance of hydrogen is very big on the other hand, can absorb a part of heat。These two aspects integrates, extremely complex, is therefore difficult to according to light intracavity gas temperature T_cavProvide downstream static temperature T。

Assume that the hydrogen flowing quantity added is only small, little of F+H₂The impact of chemical heat release can ignore (being typically set to the 0.1%～1% of combustor total gas couette), then light intracavity gas flow temperature T_cavThe downstream static temperature T being equal to after primary air is expanded by superonic flow nozzzle can be considered as, namely have following relation to set up:

T=T_cav(5)

When namely adding trace hydrogen, light intracavity gas temperature T_cavEqual to downstream static temperature T, so optically measure and obtain light intracavity gas temperature T_cavAlso it is equivalent to obtain downstream static temperature T。

(5) are brought into (4) can obtain:

$T_0=T_{\mathrm{cav}}{\left(\frac{P_0}{P}\right)}^{\frac{\mathrm{\γ}-1}{\mathrm{\γ}}}---\left(6\right)$

So far, according to upstream stagnation pressure P₀, downstream static pressure P and light intracavity gas temperature T_cav, it is possible to utilize that formula (6) is counter pushes away chamber temperature。

Wherein, the specific heat ratio γ in formula (6) can be obtained by estimation, owing to the product after burning Indoor Combustion is mainly DF, N₂, F, He etc., based on diatomic molecule and atom, and be under the condition of high temperature, Theoretical Calculation shows that the value of its specific heat ratio γ is approximately near 1.4, specifically can according to each gas flow n_iEstimating, computing formula is: $\mathrm{\γ}=\left(\mathrm{\Σ}{n}_i\frac{{\mathrm{\γ}}_i}{{\mathrm{\γ}}_i-1}\right)/\left(\mathrm{\Σ}{n}_i\frac{1}{{\mathrm{\γ}}_i-1}\right).$

Summary of the invention

It is an object of the invention to provide a kind of method utilizing trace hydrogen method to measure hydrogen fluoride laser chamber temperature。With it, can realize noting be used in combustor to open the observation window i.e. optical method for measuring chamber temperature of available non-intrusion type, and then investigate the purpose of HF laser instrument combustor operation conditions。

For realizing the purpose of the present invention, concrete technical scheme is:

A kind of method utilizing trace hydrogen method to measure hydrogen fluoride laser chamber temperature, specifically includes: (1) does not affect the trace hydrogen method for implanting of primary air aerodynamic parameter；(2) measuring method is utilized to measure the light cavity temperature of hydrogen fluoride laser；(3) according to light cavity temperature, utilize that aerodynamics is counter pushes away chamber temperature。

Not described " not affecting the trace hydrogen method for implanting of primary air aerodynamic parameter ": in measuring diagnosis process, affiliated hydrogen flowing quantity is only small, it is far smaller than the flow of hydrogen fluoride chemical laser primary air, it is typically about 0.1%～1%, to such an extent as to the exothermic heat of reaction of hydrogen and fluorine atom has little influence on the temperature of primary air。Light cavity temperature T under trace hydrogen atmosphere_cavEqual to combustion chamber gases gas static temperature T in optical cavity porch after nozzle expansion。

Described " utilizing the light cavity temperature that measuring method measures hydrogen fluoride laser ": utilize the fundamental radiation spectrum that vibration excited state fluohydric acid gas molecule measured by Fourier transform infrared spectroscopy instrument, after the rotational line intensity data of vibrational band is processed, with 1.44F_uLn (I/wag) is mapped, it is possible to obtaining straight line, the negative of this straight slope is light intracavity gas temperature。

Described " according to light cavity temperature, utilize aerodynamics is counter pushes away chamber temperature ": first measure and obtain chamber pressure P₀With cavity pressure P, and according to formulaEstimate the specific heat ratio γ of combustor primary air, obtain light cavity temperature T further according to spectrographic technique measurement_cav, according to formulaThe temperature T of combustor can be back-calculated to obtain₀。

The invention has the beneficial effects as follows:

Present invention incorporates aerodynamic technique and the advantage of non-invasive optical measurement technology, adopt the method injecting trace hydrogen, both can observe HF (v) fluorescent radiation at light intracavity, will not allow again F+H₂The highly exothermic temperature to primary air produces big interference。Achieve and not only not be used in combustor windowing but also the purpose of the non-invasive optical method airtight chamber temperature of measurement can be passed through。

Accompanying drawing explanation

Fig. 1 is the operating process schematic diagram of the present invention。Wherein, (1) calculates specific heat ratio γ according to each gas flow；(2) chamber pressure P is measured₀With cavity pressure P；(3) P0, P and calculating is utilized to obtain T₀The ratio of/T；(4) obtain according to HF (v) spectrum, under trace hydrogen atmosphere, be namely equal to the downstream static temperature T after primary air expands；(5) chamber temperature T0 is obtained according to T0/T ratio and light cavity temperature T calculating。

Fig. 2 carries out mapping obtain rotating the process of temperature for utilizing the R of (1-0) bands of a spectrum to prop up spectral line, it can be seen that the light intracavity HF molecule rotation temperature of this experiment is about 377K, and namely the macro-temperature of light intracavity gas is 377K。

Detailed description of the invention

Embodiment 1

Trace hydrogen method is once utilized to measure the example of hydrogen fluoride laser chamber temperature。

Concrete operation step is as follows:

The first step opens slide valve, evacuation, does not go out the HF chemical laser experiment of light, namely only carries out F+H2 chemical reaction and send fluorescent radiation；But there is no chamber mirror, do not have laser。

Each gas flow (mmol/s) of entry of combustion chamber is: D₂(114),NF₃(125),He(81)。

It should be noted that the amounts of hydrogen of addition is more much smaller than when normally testing, it is ensured that F+H₂Chemical heat release is without influence on primary air temperature；H₂Flow set is 3mmol/s。

The specific heat ratio γ of each admixture of gas in second step estimation combustor。

NF₃N is become through pyrolysis₂And F atom, F atom and D₂Reaction generates DF, therefore each gas flow n after after chemical reaction and pyrolysis in combustor_i(mmol/s) it is:

DF(228),F(147),N₂(62.5), He (81)；Total flow is 518.5mmol/s。

Their specific heat ratio γ_iIt is respectively as follows: DF (1.40), F (1.67), N₂(1.40), He (1.67)；

According to formulaIt is estimated that, the specific heat ratio γ of burning indoor gas is 1.49。

3rd pacing amount combustor P₀=0.95atm and cavity pressure P=6Torr。Utilize P0, P and γ to calculate and obtain T₀The ratio of/T is 4.83。

4th step gathers HF fundamental radiation spectrum, is propped up by the R of (1-0) after the intensity of spectral line carries out a series of process, with 1.44Fu to Ln (I/wag) mapping, obtains Fig. 2, and its slope is-377, so obtaining light intracavity gas temperature T_cavFor the negative of slope, i.e. 377K。

Hydrogen owing to adding in experiment is trace, in a combuster the 0.6% of total gas couette, and therefore light cavity temperature T_cavEqual to combustion chamber gases gas static temperature T, i.e. T=377K in optical cavity porch。

5th step so far already known T₀The value of/T be 4.83 and the value of T be 377K, then can obtain chamber temperature T₀For 1821K。

Claims (4)

1. one kind utilizes the method that trace hydrogen method measures hydrogen fluoride laser chamber temperature, it is characterized in that: (1) injects trace hydrogen in the optical cavity gas access place of hydrogen fluoride laser in the primary air enter optical cavity, the flow injecting trace hydrogen does not affect the aerodynamic parameter of primary air；(2) measuring method is utilized to measure the light cavity temperature of hydrogen fluoride laser；(3) according to light cavity temperature, utilize that aerodynamics is counter pushes away chamber temperature。

2. in accordance with the method for claim 1, it is characterised in that: the flow of described injection trace hydrogen does not affect the aerodynamic parameter of primary air and refers to, hydrogen is added by optical cavity gas access；Affiliated hydrogen flowing quantity is the 0.1%～1% of hydrogen fluoride chemical laser primary air flow, and the exothermic heat of reaction amount of hydrogen and fluorine atom is so little that the temperature not affecting primary air。

3. in accordance with the method for claim 1, it is characterized in that: the described light cavity temperature utilizing measuring method to measure hydrogen fluoride laser refers to, Fourier transform infrared spectroscopy instrument is utilized to measure the fundamental radiation spectrum of vibration excited state fluohydric acid gas molecule in optical cavity, after the rotation spectrum data of vibrational band are processed, with 1.44F_uTo Ln (I/wag) respectively coordinate mapping in length and breadth, it is possible to obtaining straight line, the negative of straight slope is light intracavity gas temperature T_cav。

4. in accordance with the method for claim 1, it is characterised in that: described according to light cavity temperature, utilize the anti-chamber temperature that pushes away of aerodynamics to refer to, obtain hydrogen fluoride laser chamber pressure P first with gauge measurement₀With cavity pressure P, and calculate the flow n of various gases after burning Indoor Combustion according to the initial gas flow entering combustor_i(_iThe symbol of the various gases after burning, it is the natural number of 1 to 3 or 1 to 4, n_iRepresent the_iPlant the flow of gas, γ_iRepresent the_iThe specific heat ratio of kind of gas), and then calculate the specific heat ratio of combustor exit primary air, computing formula isFurther according to light cavity temperature T_cavAnd formulaThe temperature T of burning indoor gas can be back-calculated to obtain₀。