CN112163292A - Ribbed partition nozzle modification method for improving acoustic energy dissipation - Google Patents
Ribbed partition nozzle modification method for improving acoustic energy dissipation Download PDFInfo
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- CN112163292A CN112163292A CN202011014302.6A CN202011014302A CN112163292A CN 112163292 A CN112163292 A CN 112163292A CN 202011014302 A CN202011014302 A CN 202011014302A CN 112163292 A CN112163292 A CN 112163292A
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- G06—COMPUTING; CALCULATING OR COUNTING
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- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/17—Mechanical parametric or variational design
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/28—Design optimisation, verification or simulation using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD]
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
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- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/08—Thermal analysis or thermal optimisation
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
Abstract
The invention provides a method for modifying a ribbed baffle nozzle for improving acoustic energy dissipation, which increases the contact area through ribs. The COMSOL simulation proves the effectiveness of the invention, the invention is suitable for various rocket engine partition nozzles, and an effective means is provided for inhibiting the unstable combustion of the rocket engine. Aiming at the problem that the combustion of the rocket engine is unstable by the baffle nozzle, the thermal viscous dissipation of the baffle nozzle is mainly generated at the position where the distance between the adjacent nozzles is smaller than a thermal viscous boundary layer from the aspect of acoustic energy dissipation. By increasing the contact area of the outer surfaces of adjacent nozzles, the dissipation of acoustic energy by the diaphragm nozzles can be effectively improved.
Description
Technical Field
The invention relates to a method for modifying a nozzle of a partition plate of a combustion chamber of a liquid rocket engine.
Background
The problem of unstable combustion is a worldwide problem restricting the development of liquid rocket engines, and the phenomenon of unstable over-combustion occurs in the development of most liquid rocket engine models. Acoustic instability is a form of combustion instability in a combustion chamber, where the sound waves continue to gain energy due to the coupling of unsteady combustion heat release and the combustion chamber acoustic system, ultimately producing severe pressure oscillations.
Diaphragm nozzles are an effective means for suppressing acoustic instabilities within the combustion chamber. The diaphragm nozzle increases damping through thermal viscous dissipation, changes the acoustic characteristics of the combustion chamber, and destroys oscillation conditions, thereby achieving the effect of suppressing acoustic instability. In order to obtain a better sound absorption effect, the acoustic characteristics of the diaphragm nozzle need to be studied.
At present, the clapboard nozzles for controlling unstable combustion are mainly cylindrical, and researches show that the contact area of a tiny gap area is changed by the ribs between the adjacent clapboard nozzles, so that acoustic energy dissipation can be changed, the thermal viscosity dissipation effect is improved, and the effect of enhancing and inhibiting the unstable combustion of an engine is achieved.
Disclosure of Invention
Against the above background, the present invention provides a method for modifying a ribbed baffle nozzle to improve acoustic energy dissipation by increasing the contact area of the micro-gap region through fins, thereby improving the thermal viscous dissipation effect. Through COMSOL simulation, the influence rule of various parameters in the method on acoustic energy dissipation is given, and the design of the diaphragm nozzle of the rocket engine adopting the modification method is guided.
The technical scheme adopted by the invention is as follows:
a method for modifying the shape of ribbed partition nozzle with improved acoustic energy dissipation features that the ribs are changedWidth L of1And a height L2The contact area of the micro gap area can be changed, so that the sound energy dissipation is changed, and different sound absorption effects are realized.
The ribbed baffle nozzle was simulated using COMSOL commercial simulation software, taking into account the effects of the hot tack effect. And COMSOL calculates a control equation of the calculation model, so that the distribution condition of parameters such as pressure disturbance in space can be obtained. The control equation and the calculation model are as follows:
discretizing a control equation by adopting a finite element method, wherein COMSOL gives a continuous equation under the effect of hot viscosity:
wherein i is an imaginary unit, ω is an acoustic frequency, ρ is a density, u is a velocity,
for the Hamiltonian, the parameter with index 0 represents the equilibrium value and the parameter without index 0 represents the perturbation value.
The momentum equation:
wherein, the superscript tau means the transposition of the matrix, p is the pressure, mu is the dynamic viscosity, muBFor bulk viscosity, I is the unit vector.
Energy equation:
wherein, CpThe constant pressure specific heat, the variable T is temperature, alpha is the coefficient of thermal expansion, and kappa is the coefficient of thermal conductivity.
The state equation is as follows:
ρ＝ρ0(βp-αT)
wherein β is the isothermal compressibility.
The structured grid is used in the model, and as shown in fig. 2, the minimum grid is set to 1/3 of the viscous boundary layer in consideration of computational resources and computational accuracy. Since the invention only concerns the sound absorption mechanism of the ribbed channel, an incident plane sound wave with frequency f and amplitude of 1Pa is given at the inlet, the impedance after the channel is Z ═ ρ c, and c is the sound velocity, and the sound wave reflection is not considered.
Analyzing downstream-propagated sound wave amplitude A+And the amplitude A of the acoustic wave propagating upstream-The distribution in space of (a). Defining a dissipation factor E:
subscripts 1 and 2 represent the energy loss at the inlet and outlet, respectively, the dissipation factor E representing the loss of acoustic energy due to hot tack, the greater the value, the greater the loss
Under the conditions of certain working frequency, gas temperature and environmental pressure of the rocket engine, different minimum gaps have different acoustic energy dissipation coefficients, and an optimal gap exists, so that the acoustic energy dissipation coefficient is maximum, as shown in fig. 3. FIG. 3 shows the change rule of the acoustic energy dissipation coefficient with different minimum clearances under the conditions of the working frequency of 1000Hz, the radius of the cylinder of 2.5mm and the cylindrical surface at normal temperature and normal pressure.
In the present invention, the maximum acoustic energy dissipation decreases with increasing rib width for different rib widths.
In the invention, the gap of maximum acoustic energy dissipation increases with increasing rib height for different rib heights.
In the present invention, the maximum acoustic energy dissipation decreases with increasing radius for different radii.
In the present invention, the maximum acoustic energy dissipation decreases with increasing operating frequency for different operating frequencies.
The invention has the advantages and effects that: the baffle nozzle can effectively change the sound energy dissipation, and has the advantages of simple structure, convenient installation, low cost and easy processing.
Drawings
FIG. 1 is a schematic view of a ribbed baffle nozzle.
Figure 2 geometric model and meshing.
Fig. 3 acoustic energy dissipation coefficients at different gaps.
Fig. 4 shows the variation of the acoustic energy dissipation coefficient for different rib widths.
Fig. 5 variation of the acoustic energy dissipation coefficient at different rib heights.
Figure 6 variation of the acoustic energy dissipation factor at different radii.
Figure 7 variation of the acoustic energy dissipation coefficient at different frequencies.
The symbols in the figure are as follows: radius of the R cylinder, height of the h baffle nozzle, bmMinimum gap of partition, L1Rib width, L2Rib height, E acoustic energy dissipation coefficient, f operating frequency.
The specific implementation mode is as follows:
the present invention will be described in detail below with reference to the accompanying drawings. In this embodiment, the acoustic energy dissipation is effectively changed by changing the structural parameters of the ribbed baffle nozzle, and the specific implementation is as follows:
in this embodiment, under normal temperature and pressure, the working frequency f is 1000Hz, the radius R of the cylinder of the nozzle of the partition board is 2.5mm, and the minimum gap b is selectedmThe variation range is 0-0.5 mm, and the variation rule of the maximum sound energy dissipation along with the milling degree is obtained through simulation.
Because the rocket engines of different models are different, conditions such as the cylinder radius, the working frequency and the like of the partition plate nozzle are different, and the acoustic energy dissipation needs to be calculated under different conditions in order to verify that the ribbed partition plate nozzle can effectively change the acoustic energy dissipation under various conditions.
Fig. 4 shows the change rule of the acoustic energy dissipation when the normal temperature and pressure working frequency is 1000Hz, and the rib widths are respectively 0.1mm, 0.2mm, 0.3mm and 0.4mm, and the minimum gap is changed, the change range is 0-0.5 mm. It can be seen that the maximum acoustic energy dissipation decreases with increasing rib width under different rib width conditions. It was thus verified that the ribbed baffle nozzle was able to effectively alter acoustic energy dissipation at different rib widths.
Fig. 5 shows the change rule of the acoustic energy dissipation when the normal temperature and pressure working frequency is 1000Hz, and the rib heights are respectively 0.06mm, 0.08mm, 0.1mm and 0.12mm, and the minimum gap is changed, the change range is 0-0.5 mm. It can be seen that the gap for maximum acoustic energy dissipation increases with increasing rib height under different rib height conditions. It was thus verified that the ribbed baffle nozzle was able to effectively alter the acoustic energy dissipation at different rib heights.
Fig. 6 shows the change rule of the acoustic energy dissipation when the working frequency is 1000Hz at normal temperature and normal pressure and the radius is 2mm, 3mm, 3.5mm and 4mm respectively, the minimum gap is changed, the change range is 0-0.5 mm. It can be seen that the maximum acoustic energy dissipation decreases with increasing radius at different radii. It was thus verified that the ribbed baffle nozzle was able to effectively alter the acoustic energy dissipation at different radii.
Fig. 7 shows the change rule of the acoustic energy dissipation when the working frequency is 400Hz, 800Hz, 1000Hz, 1200Hz, 1600Hz respectively at normal temperature and pressure, and the minimum gap is changed, the change range is 0-0.5 mm. It can be seen that the maximum acoustic energy dissipation decreases with increasing operating frequency under different operating frequency conditions. It was thus verified that the ribbed baffle nozzle was able to effectively alter acoustic energy dissipation at different operating frequencies.
Accordingly, according to the above results, the diaphragm nozzles are formed by a series of diaphragm nozzles extending into the combustion chamber, and the ribbed cylindrical rows of the diaphragm nozzles arranged in a certain arrangement form a cylindrical grid type sound absorption channel, so that the sound energy dissipation can be effectively changed under the conditions of different rib widths, rib heights, radii and operating frequencies.
The specific implementation process of the invention is as follows with reference to the attached drawings: the values of the parameters of the examples were set in COMSOL, simulation calculation was performed, the results were substituted into the dissipation factor defining equation, and the loss of the energy of the acoustic wave due to the thermal viscosity was analyzed.
The above description of the invention and its embodiments is not intended to be limiting, and the illustrations in the drawings are intended to represent only one embodiment of the invention. Without departing from the spirit of the invention, it is within the scope of the invention to design structures or embodiments similar to the technical solution without creation.
Claims (5)
1. A ribbed baffle nozzle profiling method for improving acoustic energy dissipation is characterized in that: varying the width L of the fins1And a height L2Namely, the contact area of the gap area is changed, so that the sound energy dissipation is changed, and different sound absorption effects are realized.
2. The method of claim 1 wherein the ribbed baffle nozzle profiling improves acoustic energy dissipation comprises: simulating the ribbed baffle plate nozzle by using COMSOL commercial simulation software in consideration of the influence of hot viscosity effect; and COMSOL calculates a control equation of the calculation model to obtain the distribution condition of parameters such as pressure disturbance and the like in the space.
3. The method of claim 2 wherein the ribbed baffle nozzle profiling improves acoustic energy dissipation comprises: the control equation and the calculation model are as follows:
discretizing a control equation by adopting a finite element method, wherein COMSOL gives a continuous equation under the effect of hot viscosity:
wherein i is an imaginary unit, ω is an acoustic frequency, ρ is a density, u is a velocity,
the parameter of subscript 0 represents a balance value, and the parameter not labeled with 0 represents a disturbance value;
the momentum equation:
wherein, the superscript tau means the transposition of the matrix, p is the pressure, mu is the dynamic viscosity, muBIs the bulk viscosity, I is the unit vector;
energy equation:
wherein, CpThe specific heat at constant pressure, the variable T is the temperature, alpha is the coefficient of thermal expansion, and kappa is the coefficient of thermal conductivity;
the state equation is as follows:
ρ＝ρ0(βp-αT)
wherein β is the isothermal compressibility.
4. A method of profiling a ribbed baffle nozzle for improved acoustic energy dissipation as defined in claim 3 wherein: structured grids are adopted, and the minimum grid is set to 1/3 of a viscous boundary layer; at the entrance, an incident planar acoustic wave of frequency f and amplitude 1Pa is given, with a channel back impedance Z ═ ρ c, and c the speed of sound, regardless of the acoustic reflection.
5. The method of claim 4 wherein the ribbed baffle nozzle profiling improves acoustic energy dissipation comprises: analyzing downstream-propagated sound wave amplitude A+And the amplitude A of the acoustic wave propagating upstream-The spatial distribution of (a); defining a dissipation factor E:
subscripts 1 and 2 represent the energy loss at the inlet and outlet, respectively, and the dissipation factor E represents the loss of acoustic energy due to hot tack, with higher values indicating higher losses.
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| CN202011014302.6A CN112163292A (en) | 2020-09-24 | 2020-09-24 | Ribbed partition nozzle modification method for improving acoustic energy dissipation |
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| CN202011014302.6A CN112163292A (en) | 2020-09-24 | 2020-09-24 | Ribbed partition nozzle modification method for improving acoustic energy dissipation |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113808565A (en) * | 2021-07-29 | 2021-12-17 | 北京航空航天大学 | Back cavity perforated partition plate nozzle capable of improving sound absorption capacity |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103032898A (en) * | 2012-12-31 | 2013-04-10 | 中国人民解放军国防科学技术大学 | Mixing enhancing device for combustion chamber |
| CN109057995A (en) * | 2018-08-03 | 2018-12-21 | 北京航空航天大学 | The partition nozzle best clearance design method and partition nozzle that can be dissipated based on sound |
| CN109268168A (en) * | 2018-11-26 | 2019-01-25 | 北京金朋达航空科技有限公司 | Height pushes away the small-size turbojet engine of ratio |
| US20200182326A1 (en) * | 2018-12-07 | 2020-06-11 | Hyundai Motor Company | Hydraulic engine mount |
| WO2020154809A1 (en) * | 2019-01-30 | 2020-08-06 | Laboratoire Reaction Dynamics Inc. | Rocket engines |
-
2020
- 2020-09-24 CN CN202011014302.6A patent/CN112163292A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103032898A (en) * | 2012-12-31 | 2013-04-10 | 中国人民解放军国防科学技术大学 | Mixing enhancing device for combustion chamber |
| CN109057995A (en) * | 2018-08-03 | 2018-12-21 | 北京航空航天大学 | The partition nozzle best clearance design method and partition nozzle that can be dissipated based on sound |
| CN109268168A (en) * | 2018-11-26 | 2019-01-25 | 北京金朋达航空科技有限公司 | Height pushes away the small-size turbojet engine of ratio |
| US20200182326A1 (en) * | 2018-12-07 | 2020-06-11 | Hyundai Motor Company | Hydraulic engine mount |
| WO2020154809A1 (en) * | 2019-01-30 | 2020-08-06 | Laboratoire Reaction Dynamics Inc. | Rocket engines |
Non-Patent Citations (2)
| Title |
|---|
| 冯若: "《超声手册》", 31 October 1999 * |
| 刘旺等: "喷嘴吸声机理研究", 《载人航天》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113808565A (en) * | 2021-07-29 | 2021-12-17 | 北京航空航天大学 | Back cavity perforated partition plate nozzle capable of improving sound absorption capacity |
| CN113808565B (en) * | 2021-07-29 | 2024-02-06 | 北京航空航天大学 | Back cavity perforation baffle nozzle capable of improving suction capacity |
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