Effects of Diverging Nozzle Downstream on Flow Field Parameters of Rotating Detonation Combustor

In this study, three-dimensional numerical studies have been performed to investigate the performance of a rotating detonation combustor with a diverging nozzle downstream. The effects of a diverging nozzle on the formation and propagation process of a detonation wave and typical flow field parameters in a rotating detonation combustor are mainly discussed. The results indicate that the diverging nozzle downstream is an important factor affecting the performance and design of a rotating detonation combustor. The diverging nozzle does not affect the formation and propagation process of the rotating detonation wave, while the time of two key wave collisions are delayed during the formation process of the detonation wave. With increases of the diverging angle, the rotating detonation combustor with the diverging nozzle can still maintain a certain pressure gain performance. Both the diverging nozzle and diverging angle have great influence on the flow field parameters of the rotating detonation combustor, including reducing the high pressure and temperature load, making the distribution of the outlet parameters uniform, and changing the local supersonic flow at the outlet. Among them, the outlet static pressure is reduced by up to 88.32%, and the outlet static temperature is reduced by up to 32.12%. This evidently improves the working environment of the combustor while reducing the thermodynamic and aerodynamic loads at the outlet. In particular, the diverging nozzle does not affect the supersonic characteristics of the outlet airflow, and on this basis, the Mach number becomes coincident and enhanced.

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Experimental investigation on the three-dimensional flow field from a meltblowing slot die

e-Polymers ◽

10.1515/epoly-2020-0058 ◽

2020 ◽

Vol 20 (1) ◽

pp. 724-732

Author(s):

Changchun Ji ◽

Yudong Wang

Keyword(s):

Flow Field ◽

Three Dimensional ◽

Great Influence ◽

Distribution Characteristics ◽

Air Velocity ◽

Three Dimensional Flow ◽

Dimensional Flow ◽

Airflow Distribution ◽

Slot Die ◽

Center Area

AbstractTo investigate the distribution characteristics of the three-dimensional flow field under the slot die, an online measurement of the airflow velocity was performed using a hot wire anemometer. The experimental results show that the air-slot end faces have a great influence on the airflow distribution in its vicinity. Compared with the air velocity in the center area, the velocity below the slot end face is much lower. The distribution characteristics of the three-dimensional flow field under the slot die would cause the fibers at different positions to bear inconsistent air force. The air velocity of the spinning centerline is higher than that around it, which is more conducive to fiber diameter attenuation. The violent fluctuation of the instantaneous velocity of the airflow could easily cause the meltblowing fiber to whip in the area close to the die.

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Design Optimization of Profiled Endwall With Consideration of Cooling and Rim Seal Flow Effects

Volume 2B: Turbomachinery ◽

10.1115/gt2016-57219 ◽

2016 ◽

Author(s):

Huimin Tang ◽

Shuaiqiang Liu ◽

Hualing Luo

Keyword(s):

High Pressure ◽

Flow Field ◽

Secondary Flow ◽

Three Dimensional ◽

Great Influence ◽

Optimization Procedure ◽

Secondary Flows ◽

High Pressure Turbine ◽

Operation Condition ◽

Turbine Performance

Profiled endwall is an effective method to improve aerodynamic performance of turbine. This approach has been widely studied in the past decade on many engines. When automatic design optimisation is considered, most of the researches are usually based on the assumption of a simplified simulation model without considering cooling and rim seal flows. However, many researchers find out that some of the benefits achieved by optimization procedure are lost when applying the high-fidelity geometry configuration. Previously, an optimization procedure has been implemented by integrating the in-house geometry manipulator, a commercial three-dimensional CFD flow solver and the optimization driver, IsightTM. This optimization procedure has been executed [12] to design profiled endwalls for a turbine cascade and a one-and-half stage axial turbine. Improvements of the turbine performance have been achieved. As the profiled endwall is applied to a high pressure turbine, the problems of cooling and rim seal flows should be addressed. In this work, the effects of rim seal flow and cooling on the flow field of two-stage high pressure turbine have been presented. Three optimization runs are performed to design the profiled endwall of Rotor-One with different optimization model to consider the effects of rim flow and cooling separately. It is found that the rim seal flow has a significant impact on the flow field. The cooling is able to change the operation condition greatly, but barely affects the secondary flow in the turbine. The influences of the profiled endwalls on the flow field in turbine and cavities have been analyzed in detail. A significant reduction of secondary flows and corresponding increase of performance are achieved when taking account of the rim flows into the optimization. The traditional optimization mechanism of profiled endwall is to reduce the cross passage gradient, which has great influence on the strength of the secondary flow. However, with considering the rim seal flows, the profiled endwall improves the turbine performance mainly by controlling the path of rim seal flow. Then the optimization procedure with consideration of rim seal flow has also been applied to the design of the profiled endwall for Stator Two.

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Experimental and three-dimensional numerical investigations on H2/air continuous rotating detonation wave

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410011433542 ◽

2012 ◽

Vol 227 (2) ◽

pp. 326-341 ◽

Cited By ~ 7

Author(s):

Shi-Jie Liu ◽

Zhi-Yong Lin ◽

Wei-Dong Liu ◽

Wei Lin ◽

Ming-Bo Sun

Keyword(s):

Detonation Wave ◽

Three Dimensional ◽

Numerical Investigations ◽

Rotating Detonation

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Introduction of DMD Method to Study the Dynamic Structures of a Three-Dimensional Centrifugal Compressor with and without Flow Control

Energies ◽

10.3390/en11113098 ◽

2018 ◽

Vol 11 (11) ◽

pp. 3098 ◽

Cited By ~ 4

Author(s):

Shuli Hong ◽

Guoping Huang ◽

Yuxuan Yang ◽

Zepeng Liu

Keyword(s):

Flow Field ◽

Flow Control ◽

Centrifugal Compressor ◽

Coherent Structures ◽

Three Dimensional ◽

Great Influence ◽

Flow Structures ◽

Small Scale ◽

Dynamic Mode ◽

Blade Tip

The flow structures around the blade tip, mainly large-scale leakage vortex, exert a great influence on compressor performance. By applying unsteady jet control technology at the blade tip in this study, the performance of the compressor can be greatly improved. A numerical simulation is conducted to study the flow characteristics of a centrifugal compressor with and without a flow control. The complex flow structures cause great difficulties in the analysis of the dynamic behavior and flow control mechanism. Thus, we introduced a dynamic flow field analysis technology called dynamic mode decomposition (DMD). The global spectrums with different global energy norms and the coherent structures with different scales can be obtained through the DMD analysis of the three-dimensional controlled and uncontrolled compressors. The results show that the coherent structures are homogeneous in the controlled compressor. The leakage vortex is weakened, and its influence range of unsteady fluctuation is reduced in the controlled compressor. The effective flow control created uniform vortex structures and improved the overall order of the flow field in the compressor. This research provides a feasible direction for future flow control applications, such as transferring the energy of the dominant vortices to small-scale vortices.

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Experimental research on the propagation process of rotating detonation wave with a gaseous hydrocarbon mixture fuel

Acta Astronautica ◽

10.1016/j.actaastro.2020.10.027 ◽

2021 ◽

Vol 179 ◽

pp. 1-10

Author(s):

Shengbing Zhou ◽

Hu Ma ◽

Changsheng Zhou ◽

Ning Hu

Keyword(s):

Detonation Wave ◽

Experimental Research ◽

Hydrocarbon Mixture ◽

Propagation Process ◽

Gaseous Hydrocarbon ◽

Rotating Detonation

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Numerical study on three-dimensional flow field of continuously rotating detonation in a toroidal chamber

Acta Mechanica Sinica ◽

10.1007/s10409-012-0005-y ◽

2012 ◽

Vol 28 (1) ◽

pp. 66-72 ◽

Cited By ~ 1

Author(s):

Xu-Dong Zhang ◽

Bao-Chun Fan ◽

Ming-Yue Gui ◽

Zhen-Hua Pan ◽

Gang Dong

Keyword(s):

Flow Field ◽

Numerical Study ◽

Three Dimensional ◽

Three Dimensional Flow ◽

Dimensional Flow ◽

Rotating Detonation ◽

Toroidal Chamber

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Multi-Dimensional Numerical Free Surface VOF Modeling With Moonpool Experiments

Volume 5: Materials Technology; CFD and VIV ◽

10.1115/omae2008-57422 ◽

2008 ◽

Author(s):

Salman Sadiq ◽

Xiong-Liang Yao

Keyword(s):

Free Surface ◽

Flow Field ◽

Best Practice ◽

Three Dimensional ◽

Great Influence ◽

Numerical Results ◽

Experimental Comparison ◽

Pressure Distributions ◽

Entire Flow ◽

Set Up

The homogeneous multiphase incompressible flow past a moonpool was investigated to determine the shape of vortex, flow field and pressure distributions. In this approach, a homogeneous flow model together with the VOF method for interface capturing is used to compute the entire flow field within the moonpool. The turbulence is represented via fully homogeneous buoyant model with air and water as continuous fluids. Numerical results are verified by conducting towing tank experiments. Simulation ship moonpool applications are verification of capabilities in ANSYS CFX multi-physics code by two and three dimensional circular and square shaped moonpool subjected to flow in a channel. The numerical results indicate that cavity location with a unit factor of 1.667(L/L1), where ‘L’ is length of cavity and ‘L1’ is the distance from inflow edge; was proved to be appropriate for such cavities to have optimum performance related to moonpool hydrodynamics. Distance ‘L2’ had a negligible effect on cavity. Free surface height ‘H’ inside the cavity was maintained at 0.4 m both in numerical calculations then in experiments. Numerical and experimental comparison of results reveals that due to multiphase modeling; results diverge from actual value near phase coupling. Shape factor like internal curvature, has a great influence on vortex shape and hydrodynamic forces inside the moonpool. By analyzing these numerical results a better understanding is established for VOF models and moonpool piston phenomenon. Square shaped moonpool results and numerical results agree very well till half of the moonpool depth from free surface height. These results can be very well used for the basis of designing complex shaped moonpool having free surface. The agreement with the experimental data is within the accuracy of other simulations. Further studies and the development of Best Practice Procedures are required as a next step to reduce/avoid numerical and set-up errors and establish CFD as an industrial tool.

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A study of droplet evaporation coupling model based on Eulerian method

Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería ◽

10.23967/j.rimni.2021.01.001 ◽

2020 ◽

Vol 36 (4) ◽

Author(s):

Y. Tang ◽

J. Shang ◽

Y. Zhan

Keyword(s):

Flow Field ◽

Three Dimensional ◽

Great Influence ◽

Wind Tunnel Test ◽

Internal Flow ◽

Coupling Model ◽

One Dimensional ◽

Model Based ◽

Eulerian Method ◽

Thermodynamic Coupling

Research on engine icing is a hot topic among the world. Different from the aircraft wing or airframe icing, the evaporation phenomenon in the internal flow field has a great influence on the engine icing. Moreover, the thermodynamic coupling between droplets and flow field is not available in current particle trajectory calculations, or only for one-dimensional situation. Therefore, a three-dimensional droplet trajectory calculation model based on Eulerian method is used to demonstrate the thermodynamic coupling between droplets and flow field. The model was verified by NRC small engine icing wind tunnel test data and the flow field evolution is obtained which cannot be obtained by the one-dimensional coupling model. In the meanwhile, the effects of different initial LWC, relative humidity and MVD on the internal flow evaporation were studied, and the trends of droplets and flow field affected by evaporation were obtained. The numerical method in this paper can provide guidance for the subsequent research on engine icing.

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