Computation of an Exhaust System Flow Field and Infrared Radiation

2009 ◽  
Author(s):  
Jiandong Zhang ◽  
Zhanxue Wang ◽  
Yuanhu Cai
Keyword(s):  
Flow Field ◽  
Infrared Radiation ◽  
Exhaust System ◽  
System Flow

Study on the Influence of Film Cooling on the Flow Field and Infrared Radiation Characteristics in the Divergent Section of a Nozzle

2020 ◽  
Author(s):  
Haoqi Yang ◽  
Qingzhen Yang ◽  
Saile Zhang ◽  
Huicheng Yang ◽  
Yubo He
Keyword(s):  
High Temperature ◽  
Flow Field ◽  
Infrared Radiation ◽  
Film Cooling ◽  
Exhaust System ◽  
Line Pattern ◽  
Radiation Characteristics ◽  
Core Zone ◽  
The Core ◽  
Significant Difference

Abstract As the last part of the convergent divergent nozzle, the divergent section is exposed to high temperature and high-speed airflow and thus, it is more easily to be detected by the infrared detector. It is one of the main sources of the infrared radiation in the exhaust system. Film cooling is applied to protect the wall from hot flow and reduce the infrared radiation. In this paper, the study is conducted on a nozzle with spherical convergence flap in a turbofan engine exhaust system. The effect of film cooling on the internal flow and infrared radiation characteristics of the exhaust system in the divergent section was studied by numerical simulations. The k-ω SST turbulence model was used to simulate the flow field, and the Reverse Monte Carlo Method was employed to calculate the infrared radiation characteristics of the nozzle. Four different kinds of film hole arrangements are involved, they are cylindrical film holes in an in-line pattern, cylindrical film holes in a staggered pattern, converging-expanding film holes in an in-line pattern and converging-expanding film holes in a staggered pattern. The cylindrical film hole and the converging-expanding film hole have a round shape inlet, with an equivalent diameter of d = 5mm on the projection surface perpendicular to the axial direction. Angles between each film hole and the wall surface are 35°. The impact of the heat conduction on the wall was taken into account. The results show that with the given mass flow rate of the coolant, the lengths of the high temperature core zone of the four models with different film cooling structures are slightly shorter than the core zone of the model without cooling structures. However, no significant difference can be found for the length of the core zone of the four models. The average temperature of the wall in the divergent section decreases significantly by using film cooling. No significant difference can be found in the wall temperature distribution for the four models. In the 3∼5μm and 8∼14μm bands, the cooling technique barely affects the infrared radiation of the main exhaust jet flow, while it significantly reduces the infrared radiation of the solid wall in the divergent section, and the decreasing amplitude is from 45% to 51%. Different film hole arrangements result in similar effects on the infrared radiation of the nozzle. Overall, the usage of film cooling in the divergent section of the nozzle effectively reduces the averaged wall temperature and substantially suppresses the solid infrared radiation on the wall. However, the shape and arrangement of the film holes have no significant influence on the infrared radiation intensity and temperature of the wall in the divergent section.

Numerical Simulation on the Infrared Radiation Characteristics of Ejector Nozzle Based on RMCM

2011 ◽  
Vol 138-139 ◽  
pp. 879-885
Author(s):  
Li Hai Chen ◽  
Qing Zhen Yang ◽  
Jin Hui Cui
Keyword(s):  
Flow Field ◽  
Infrared Radiation ◽  
Exhaust System ◽  
Three Dimension ◽  
Radiation Characteristics ◽  
Lateral Direction ◽  
Average Temperature ◽  
System A ◽  
Infrared Intensity ◽  
Ejector Nozzle

Based on the numerical calculation of three-dimension flow field of the exhaust system, a code is developed by the reverse Monte-Carlo method (RMCM) to simulate the infrared radiation characteristics of the aeroengine exhaust system and the plume. A ray-tracing method (RTM) is introduced to seek the meshes of the flow field which the ray travels through to avoid the trouble of interpolation. The infrared radiation characteristics of a certain turbo-fan engine’s ejector nozzle in the waveband of 3-5μm is simulated at non-afterburning condition. The results of the simulation show that : (1)Because of the introduction of the secondary flow, the average temperature of the ejector nozzle’s core plume is 20K lower than the baseline one’s.(2) The infrared intensity for the ejector nozzle is most reduced relatively by 44.5% in comparison with the baseline nozzle along lateral direction.(3) The ejector nozzle has a better performance of infrared stealth.

scholarly journals A method based on ejector technology to suppress the infrared radiation of the special vehicle exhaust gas

2020 ◽  
pp. 315-315
Author(s):  
Yunsong Feng ◽  
Wei Jin ◽  
Jin Wang ◽  
Yuan Lu
Keyword(s):  
Flow Field ◽  
Radiation Intensity ◽  
Infrared Radiation ◽  
Gas Flow ◽  
Exhaust System ◽  
Exhaust Pipe ◽  
Exhaust Gas ◽  
Vehicle Exhaust ◽  
Before And After ◽  
Special Vehicle

In this study, a method based on ejector technology is proposed to effectively suppress the infrared radiation associated with the exhaust gas of special vehicles such as tanks, armored vehicles, and missile carriers. These vehicles emit exhaust gases at very high temperatures. First, a mathematical model of the exhaust pipe was established for the exhaust system of a certain type of special vehicle. Then, the three-dimensional flow field outside the exhaust pipe was numerically simulated using Fluent 6.3 software. Thus, the temperature, pressure, and density of the exhaust-gas flow field before and after adopting the proposed ejector technique were obtained. Second, the statistical narrowband model based on the Lorentzian profile was used to determine the average absorption coefficient of a narrow band. Then, the finite volume method was used to solve the radiation transfer equation in the gaseous medium. Finally, the spectral radiation brightness and mid-infrared radiation intensity distribution of the exhaust gas before and after adopting the ejector technique were obtained. Results show that the proposed method considerably decreased the infrared radiation intensity of the exhaust gas by approximately 70%. Thus, using the proposed ejector technology, the infrared radiation associated with the exhaust system of special vehicles can be effectively suppressed.

scholarly journals Analysis of Infrared Radiation Intensity by Water-Mist Spraying in Ship Exhaust System

2021 ◽  
Vol 2112 (1) ◽  
pp. 012019
Author(s):  
Zhongke Sun ◽  
Zhen Wang ◽  
Zhongwei Chen ◽  
Zhihua Liu ◽  
Mo Liu ◽  
...  
Keyword(s):  
Radiation Intensity ◽  
Infrared Radiation ◽  
Exhaust System ◽  
Water Mist ◽  
Mist Cooling

Abstract The infrared radiation intensity in 3~5μm of conventional ship exhaust system are so severe [1] that can be easily captured by detector. Therefore, it’s necessary to take measure like spraying water mist to decrease temperature of exhaust system in order to decrease infrared radiation intensity. In this paper, the calculation of infrared radiation intensity of conventional ship exhaust system with water-mist spraying will be given. The results show that the average and maximum infrared radiation intensity of the exhaust system can be reduced by 90.3% and 95.7% after water mist cooling.

scholarly journals Study on a calculation model of infrared radiation characteristics of rocket engine plume

2021 ◽  
Vol 2125 (1) ◽  
pp. 012006
Author(s):  
Nan Wu ◽  
Chengpo Mu ◽  
Yang He ◽  
Huan Liu ◽  
Taiye Liu
Keyword(s):  
Flow Field ◽  
Infrared Radiation ◽  
Rocket Engine ◽  
Calculation Model ◽  
Characteristic Parameters ◽  
Infrared Band ◽  
Radiation Characteristics ◽  
Mid Infrared ◽  
Fast Calculation ◽  
Plume Flow

Abstract In order to study the infrared radiation (IR) characteristics of rocket engine plume in the mid infrared band, a calculation model for IR transfer of rocket engine plume was built. The flow field data are calculated by software FLUENT. Based on HITRAN database, the IR characteristic parameters are calculated after spectral line correction. The Line of Sight (LoS) is used to solve the radiation characteristics in the plume flow field, and the IR characteristics distribution of the plume in the mid infrared band is obtained, which agree well with the results from open literature. The method has the advantages of simple model, less parameters and fast calculation speed in this paper.

Nozzle dimension design for aircraft engine infrared signature and thrust active control using MOEA/D

2020 ◽  
Vol 234 (15) ◽  
pp. 2133-2138
Author(s):  
Yu Zhao ◽  
Shijie Zheng
Keyword(s):  
Nozzle Exit ◽  
Infrared Radiation ◽  
Exhaust System ◽  
Aircraft Engine ◽  
Radiation Energy ◽  
Diameter Ratio ◽  
Rear Side ◽  
Military Aircraft ◽  
Infrared Signature ◽  
Aircraft Survivability

Aircraft infrared signature is one of the most important properties for the military aircraft survivability. In terms of military aircraft, the exhaust system is the most significant infrared radiation source. The exhaust system accounts for more than 90% of the aircraft infrared radiation, and that the exhaust nozzle contributes the most significant infrared radiation of the whole radiation energy provided by the exhaust system from the rear aspect. Low detectionable feature for military aircraft has attracted more importance to promote aircraft survivability via reducing infrared signature. The alteration of nozzle exit area affects an aircraft engine performance; meanwhile, it severely influences the engine infrared signature radiation from the rear side. The present paper is mainly focused on searching an appropriate group of nozzle exit diameter and throat to exit diameter ratio, which can reduce infrared signature radiation while cutting down the loss of thrust. Hence, objectives involve two aspects: one is minimum infrared signature level, and the other is minimum thrust loss. The multi-objective evolutionary algorithm based on decomposition has been employed to solve this bi-objective optimization problem. The optimization results illustrate that dimension selection range and throat to exit diameter ratio exert more important effect on the thrust loss and infrared signature level. Furthermore, the thrust plays significant role for deciding nozzle exit diameter and throat diameter.

The influence of nozzle deflection on fluid dynamic and infrared characteristics of a two-dimensional convergent–divergent vectoring exhaust system

2019 ◽  
Vol 233 (12) ◽  
pp. 4646-4662
Author(s):  
Hao Wang ◽  
Honghu Ji ◽  
Haohao Lu
Keyword(s):  
Mass Flow ◽  
Infrared Radiation ◽  
Deflection Angle ◽  
Thrust Force ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Exhaust System ◽  
Two Dimensional ◽  
Radiation Characteristics ◽  
Significant Information

Superior maneuverability and good infrared stealthy properties are two key points of the future aircraft. A two-dimensional convergent–divergent (2D-CD) vectoring exhaust system can improve the maneuverability of aircrafts and has been widely applied to the latest generation aircrafts. Understanding fluid dynamic and infrared radiation characteristics of the 2D-CD vectoring exhaust systems under different conditions of the nozzle deflection is very crucial, which can provide significant information for the suppression of the infrared radiation property of the 2D-CD vectoring exhaust system. In this paper, by means of computational fluid dynamics, the fluid dynamic and infrared radiation characteristics of the 2D-CD vectoring exhaust system are studied at subsonic cruise status with nozzle deflection angles from 0 to 20°, and the results are compared with those of the baseline axisymmetric exhaust system. The results indicate that the fluid dynamic performance of a properly designed 2D-CD vectoring exhaust system is equivalent to the fluid dynamic performance of the baseline axisymmetric exhaust system. When the nozzle deflection angle is less than 5°, the mass flow and thrust force of the 2D-CD vectoring exhaust system are almost unchanged, and with the increase of the nozzle deflection angles, the mass flow and thrust force decrease rapidly. The thrust force deflection angles lag behind the nozzle deflection angles all the time, and as the nozzle deflection angle increases, the difference between them decreases. The direction of the maximum infrared radiation of the 2D-CD vectoring exhaust system deflects with the deflection of the nozzle, and the mean integrated infrared radiation intensity of the exhaust system decreases with the increase of nozzle deflection angles.

The Method for Numerical Simulation of the Impact on the Infrared Radiation Seeker from the Warhead Shock Layer

2013 ◽  
Vol 390 ◽  
pp. 464-467
Author(s):  
Da Lei Luo ◽  
Jun Liu ◽  
Yuan Wang ◽  
Deng Feng Fan
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Radiation Field ◽  
Shock Layer ◽  
Infrared Radiation ◽  
Wave Band ◽  
Radiation Wave ◽  
Main Mirror ◽  
The Impact ◽  
Calculated Model

It counts the impact on the infrared radiation seeker which in the head of the hypersonic missile. Firstly, it built the calculated model based on the shape of a missile, and compartmentalized the aerodynamics flow field grid , the infrared radiation seeker main mirror grid , the radiation field grid, and had the relation of the grids unambiguous, and got the communication of the aerodynamics flow field. Then it educed irradiance formula about the shock layer aerodynamic flow fled radiation affect to the infrared radiation seeker main mirror. The result is the infrared radiation wave band 3~5 to the main mirror, from the shock layer aerodynamic flow fled is about 120 W/m2. The distributing law of the impact is annular circumfused the center of the main mirror, the infrared radiation is the highest in the center of the main mirror, decreased by the radius of the main mirror.

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