scholarly journals Numerical Investigation of an Axisymmetric Model Scramjet Assisted with Cavity of Different Aft Wall Angles

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Guangwei Ma ◽  
Mingbo Sun ◽  
Guoyan Zhao ◽  
Pei Liu ◽  
Tao Tang ◽  
...  
Keyword(s):  
Flow Field ◽  
Shear Layer ◽  
Three Dimensional ◽  
Combustion Efficiency ◽  
Main Flow ◽  
Mixing Efficiency ◽  
Reacting Flow ◽  
Wall Angle ◽  
Axisymmetric Model ◽  
Fuel Mixing

An axisymmetric model scramjet assisted with cavity flameholder is numerically investigated. Three-dimensional Reynolds-averaged Navier-Stokes simulation is carried out to reveal the fuel mixing and combustion characteristics. The simulation results show reasonable agreements with experimental data. The analysis indicates that the axisymmetric and rectangular scramjet has some similarities to the cavity shear layer in the nonreacting flow field. The configuration of the cavity shear layer changes hugely due to the significant chemical reaction and heat release in the reacting flow field. Typically, two more configurations with different cavity aft wall angles are compared with the experimental configuration to optimize the configuration of the cavity. When the cavity aft wall angle is small, the cavity shear layer bends to the cavity floor and more fuel enters into and stays in the cavity, which results in poor fuel mixing performance. With the increase of the aft wall angle, the fuel distributes more uniformly and the fuel mixing efficiency improves. In the reacting flow field, the volume of the cavity full of hot products and free radicals increases while the interaction between the cavity and main flow decreases with the increase of the aft wall angle. The improved combustion efficiency shows that larger cavity volume weighs more than reduced interaction between the cavity and main flow. The combustion is more violent in the case with a larger aft wall angle. Therefore, a proper increase of the aft wall angle is beneficial to the performance of cavity-assisted axisymmetric scramjet when designing the cavity flameholder.

Experimental and Numerical Investigation of the Unsteady Leakage Flow Through the Rotor Tip Labyrinth of a 1.5-Stage Axial Turbine

2005 ◽  
Author(s):  
K. Wolter ◽  
A. Giboni ◽  
P. Peters ◽  
J. R. Menter ◽  
H. Pfost
Keyword(s):  
Flow Field ◽  
Flow Direction ◽  
Three Dimensional ◽  
Calculated Data ◽  
Leading Edge ◽  
Numerical Data ◽  
Potential Effect ◽  
Main Flow ◽  
Leakage Flow ◽  
Axial Turbine

This paper presents the results of unsteady probe measurements and numerical flow calculations in a 1.5-stage low speed axial turbine with a straight labyrinth seal on a rotor shroud. The unsteady development of the leakage flow in the three cavities is described and analysed in detail. For the investigation of the leakage flow detailed time-accurate measurements of the three-dimensional flow field were carried out in five measurement planes from casing to the rotor shroud over more than one pitch. These measurements were carried out with a miniature pneumatic five-hole probe and miniature triple hot-wire probes. Both probes have a spherical head for better adjustment in flow direction. The high resolution of 330 measurement points in each of the five measurement planes represents the flow field in great detail. The unsteady experimental data was compared with the results of the unsteady numerical simulation of the turbine flow, calculated by the 3D-Navier-Stokes Solver CFX-TASCflow. The calculated data correspond well with the experimental results and allow a detailed analysis of the flow in the cavities of the labyrinth. As demonstrated in this paper the investigations show that the leakage flow at the inlet ant outlet of the labyrinth is strongly influenced by the different positions of the rotor to the stator. The unsteady experimental and numerical data indicates intensive effects of the leakage flow caused and influenced by the trailing edge of the first stator and the potential effect of the rotor leading edge. An intensive vortex develops depending on the rotor position in the first cavity. This vortex is also influenced by a small corner vortex above the axial inlet gap of the labyrinth. After the fins this unsteady influence of the leakage flow decreases and below the jet a large vortex moves in circumferential direction. The intensity of this circulation vortex is reduced at the end of the last cavity due to the interaction with the main flow and the flow direction out of the labyrinth. Therefore the unsteady behaviour of the leakage flow grows up, which is also caused by its uneven entry into the main flow.

Numerical Characterisation of a Gas Turbine Model Combustor Applying Scale-Adaptive Simulation

2009 ◽  
Author(s):  
Axel Widenhorn ◽  
Berthold Noll ◽  
Manfred Aigner
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Mixture Fraction ◽  
Thermal Power ◽  
Three Dimensional ◽  
Combustion Model ◽  
Reacting Flow ◽  
Adaptive Simulation ◽  
Power Load ◽  
Turbine Model

In this contribution the three-dimensional reacting turbulent flow field of a swirl-stabilized gas turbine model combustor is analyzed numerically. The investigated partially premixed and lifted CH4/air flame has a thermal power load of Pth = 35kW and a global equivalence ratio of φ = 0.65. To study the reacting flow field the Scale Adaptive Simulation (SAS) turbulence model in combination with the Eddy Dissipation/Finite Rate Chemistry combustion model was applied. The simulations were performed using the commercial CFD software package ANSYS CFX-11.0. The numerically achieved time-averaged values of the velocity components and their appropriate turbulent fluctuations (RMS) are in very good agreement with the experimental values (LDA). The same excellent results were found for other flow quantities like temperature and mixture fraction. Here, the corresponding time-averaged and the appropriate RMS profiles are compared to Raman measurements. Furthermore the instantaneous flow features are discussed. In accordance with the experiment the numerical simulation evidences the existence of a precessing vortex core (PVC). The PVC rotates with a frequency of 1596Hz. Moreover it is shown that in the upper part of the combustion chamber a tornado-like vortical structure is established.

Flow Field Analysis and Numerical Simulation for Dynamic Filtration with Rotating Disks

2012 ◽  
Vol 184-185 ◽  
pp. 244-247
Author(s):  
Zhong Bin Liu ◽  
Feng Luo
Keyword(s):  
Flow Field ◽  
Mechanical Stability ◽  
Three Dimensional ◽  
Main Flow ◽  
Field Analysis ◽  
Rotating Disks ◽  
Dynamic Filtration ◽  
Circular Flows ◽  
Flow Field Analysis ◽  
Graphics Software

Dynamic filtration with rotating disks is modeled by three-dimensional graphics software and its flow field is analyzed and numerical simulated by CFD software. The mechanical stability of dynamic filtration with rotating disks in the work process is analyzed by the model of rotating flow. The results show that the farthest end of rotating disks exit the largest flow velocity. There are two circular flows, which can remove the pollutants of rotating disks. The pressure of water is gradually increased as the main flow is near cylinder of the filtration. Simulation results are consistent to the practice, which provides important theoretical basis for improving and optimization of dynamic filtration with rotating disks.

Flow Field Analysis and Numerical Simulation for Pipe with Tee on Fluid-Structure Coupling

2012 ◽  
Vol 503-504 ◽  
pp. 768-771
Author(s):  
Zhong Bin Liu ◽  
Feng Luo ◽  
Tao Zeng ◽  
Hui Wu
Keyword(s):  
Flow Field ◽  
Mechanical Stability ◽  
Three Dimensional ◽  
Main Flow ◽  
Field Analysis ◽  
Fluid Structure ◽  
Coulomb Failure ◽  
Flow Field Analysis ◽  
Simulation Results ◽  
Graphics Software

Y-shaped tee is modeled by three-dimensional graphics software and its flow field is analyzed and numerical simulated by CFD software. The mechanical stability of Y-shaped tee in the work process is analyzed by fluid-structure coupling. The results show that the pressure of water is gradually decreased and the velocity of water is gradually increased as the main flow is near Y-shaped tee; the branch of pipeline exits the largest failure risk by the coulomb failure expression. Simulation results are consistent to the practice, which provides important theoretical basis for improving and optimization of Y-shaped tee.

scholarly journals Influence of Core Swirling Motion on Aerodynamic Performances of Lobed Exhaust Nozzle

2019 ◽  
Author(s):  
Yulin Ding ◽  
Youhong Liu ◽  
Liwei Du
Keyword(s):  
Flow Field ◽  
Cross Section ◽  
Stokes Equations ◽  
Model Simulation ◽  
Computational Simulation ◽  
Three Dimensional ◽  
Mixing Efficiency ◽  
Recovery Coefficient ◽  
Thermal Mixing ◽  
Aerodynamic Performances

Influence of core flow inlet swirl angle on aerodynamic performances of an exhaust nozzle with scarfed lobed mixer was studied by the validated computational approach. The computational simulation was conducted by resolving the steady form of discretized three-dimensional Reynolds Averaged Navier-Stokes equations with the shear stress transport k-Ω turbulence model. Simulation results depict that swirling motions have ignorable influence on the flow field of the top part in the cross sections slightly downstream of the lobed trailing edge. Besides, for the flow field downstream of the L/D=0.1 cross section, the swirling motions are suggested to cause the clockwise stream-wise vortex to stretch into several smaller-scale vortexes. When the case with a bigger swirling angle is investigated, the induced smaller-scale vortexes are more strengthened by the swirling motions. Concerning the 15° swirling case, the loss caused by the destroyed vortex pattern and the benefit induced by the improved smaller-scale vortexes almost counteract with each other with respect to the thermal mixing efficiency. In the last studied cross section as compared with the baseline case, the case with a maximum swirling angle of 30° has increased 6.94% for the thermal mixing efficiency and decreased 0.42% for the total pressure recovery coefficient.

Three-Dimensional Modeling of Reacting Flows in Horseshoe Vortex Combustors

1984 ◽  
Author(s):  
A. Turan ◽  
N. G. Ruggieri ◽  
G. E. Smith ◽  
B. C. Forbes
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Horseshoe Vortex ◽  
Reacting Flows ◽  
Reacting Flow ◽  
Test Results ◽  
The Real ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Analytical Results

AVCO Lycoming’s circumferentially stirred combustor employs a well-established vortex, in the shape of a horseshoe with fuel injected at the apex, to promote mixing in each sector of the annulus. This paper presents the results from three-dimensional viscous flow analyses of the reacting flow field in this type of combustor. Three designs are examined — an idealized design, used for investigating how to implement the concept, and two real designs. The analytical results agree well with test results for the real designs. Of greater engineering interest, however, the analytical results reveal how the real designs work differently from the idealized design, and they explain why the two real designs contrast sharply with one another in performance.

scholarly journals Local Measurements in a Three Dimensional Jet-Stabilized Model Combustor

1995 ◽  
Author(s):  
H. J. Bauer ◽  
L. Eigenmann ◽  
B. Scherrer ◽  
S. Wittig
Keyword(s):  
Flow Field ◽  
Modular Design ◽  
Numerical Models ◽  
Measurement Techniques ◽  
Three Dimensional ◽  
Internal Heat ◽  
Flame Stabilization ◽  
Laser Doppler Velocimeter ◽  
Reacting Flow ◽  
Primary Zone

Measurements of velocity, temperature and species concentration in a three dimensional jet-stabilized combustor are presented. The modular design of the combustor permits the use of either gaseous or liquid fuels. For the investigations presented here, fuel oil has been chosen which is atomized by an air-blast atomizer. Access to the reacting flow field for probes as well as for non intrusive optical measurement techniques is provided by several windows along the combustor axis. Velocity measurements in the mixing zone and even in the primary zone of the combustor are performed by means of a two-component Laser Doppler Velocimeter (LDA). Platinum rhodium/platinum thermocouples (PtRh/Pt) specially designed for reduced internal heat losses are used for the investigation of the temperature field. A cranked, water cooled probe is employed in order to detect local species concentrations. The experimental results reveal detailed information about the characteristics of the reacting flow field. The interaction of fuel atomization and flame stabilization in the primary zone is illustrated by a direct comparison with experimental data of the gaseous fuel case investigated earlier [ 1 ]. The results gained here serve as an excellent database to verify numerical models for the description of liquid spray combustion.

Numerical Simulation and Performance Prediction of Multistage Canned Motor Pump

2016 ◽  
Author(s):  
Bin Xia ◽  
Fan-Yu Kong ◽  
Yuxing Bai ◽  
Xiaohui Duan
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Performance Prediction ◽  
Three Dimensional ◽  
Internal Flow ◽  
Main Flow ◽  
Three Dimensional Model ◽  
Local Flow ◽  
And Performance ◽  
Canned Motor

Due to the advantages of high head and no leakage, multistage canned motor pump is widely used in oil industry, chemical industry, national defense and atomic energy. In order to meet the needs of the market, the multistage canned motor pump is designed. This paper introduced the hydraulic design and structural design. In order to optimizing the performance of the pump, this paper designed and used multistage canned motor pump DBP15–50×8 as the research object. Three-dimensional model of the main flow passage components is built and the mesh is generated respectively by using Pro/E and ICEM software, and we calculated the whole internal flow field of the pump that was selected by using ANSYS CFX14.0 software, achieving the pressure and velocity distribution in the pump and the internal details of flow in impeller and other main flow components. The post-processing showed the fluid in sliding bearing section rotates around the shaft, so the local flow is disorder. The comparison of the performance prediction and the experiment shows that the error is low. The cavitating turbulent flow in the flow field was numerically simulated by using the cavitation model. The cavitation phenomena didn’t occur in the experiments. The condition meets the result of numerical simulation.

The Applicability of Jet-Shear-Layer Mixing and Effervescent Atomization for Low-NOx Combustors

1998 ◽  
Vol 120 (1) ◽  
pp. 17-23
Author(s):  
R. O. Colantonio
Keyword(s):  
Shear Layer ◽  
Combustion Zone ◽  
Experimental Testing ◽  
Three Dimensional ◽  
Combustion Efficiency ◽  
Rich Mixture ◽  
Three Dimensional Modeling ◽  
Air Jets ◽  
Effervescent Atomizer ◽  
Modeling Code

An investigation has been conducted to develop appropriate technologies for a low-NOx, liquid-fueled combustor. The combustor incorporates an effervescent atomizer used to inject fuel into a premixing duct. Only a fraction of the combustion air is used in the premixing process. This fuel-rich mixture is introduced into the remaining combustion air by a rapid jet-shear-layer mixing process involving radial fuel–air jets impinging on axial air jets in the primary combustion zone. Computational modeling was used as a tool to facilitate a parametric analysis appropriate to the design of an optimum low-NOx combustor. A number of combustor configurations were studied to assess the key combustor technologies and to validate the three-dimensional modeling code. The results from the experimental testing and computational analysis indicate a low-NOx potential for the jet-shear-layer combustor. Key features found to affect NOx emissions are the primary combustion zone fuel–air ratio, the number of axial and radial jets, the aspect ratio and radial location of the axial air jets, and the radial jet inlet hole diameter. Each of these key parameters exhibits a low-NOx point from which an optimized combustor was developed. Also demonstrated was the feasibility of utilizing an effervescent atomizer for combustor application. Further developments in the jet-shear-layer mixing scheme and effervescent atomizer design promise even lower NOx with high combustion efficiency.

Investigation of Turbulent Models for the Flow Field From a Typical Strut-Based Scramjet Combustor

2011 ◽  
Author(s):  
Shi-bin Luo ◽  
Wei Huang ◽  
Hui Qin ◽  
Zhen-guo Wang ◽  
Jun Liu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Shear Layer ◽  
Flow Fields ◽  
Numerical Results ◽  
Reflected Shock Wave ◽  
Small Scale ◽  
Reacting Flow ◽  
Scramjet Combustor ◽  
Turbulent Models

The two-dimensional coupled implicit RANS equations and three turbulent models have been employed to numerically simulate the nonreacting and reacting flow fields of a typical strut-based scramjet combustor, and the numerical results have been compared with the experimental data. At the same time, three different grid scales have been used to test the grid independence in the numerical simulations, namely the small scale (81,590 nodes), the moderate scale (98,510 nodes) and the large scale (147,470 nodes). The obtained results show that the RNG k-ε model is more suitable to numerically simulate the flow field in the scramjet combustor than the realizable k-ε model and the SST k-ω model, and the numerical results obtained by the moderate and large grid scales show reasonably better agreement with the experimental data. The quasi-diamond wave system is formed in both the nonreacting and reacting flow fields. In the reacting flow field, there are two clear strong shear layers generated between the fuel injection and the supersonic freestream, and at the intersection point between the shear layer and the reflected shock wave, the reaction zone is broader than anywhere else. In the corner formed between the upper surface of the strut and the shear layer, an expansion wave is clearly generated, and another also exists in the symmetrical corner.

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