scholarly journals An Efficient Numerical Method for Pressure Loss Investigation in an Oil/Air Separator with Metal Foam in an Aero-Engine

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 346 ◽  
Author(s):  
Lifen Zhang ◽  
Xiaoxue Zhang ◽  
Zhenxia Liu
Keyword(s):  
Porous Media ◽  
Pressure Drop ◽  
Numerical Method ◽  
Working Conditions ◽  
Pressure Loss ◽  
Metal Foam ◽  
Speed Increase ◽  
Rotating Speed ◽  
Aero Engine ◽  
Resistance Coefficients

An efficient method of simulating pressure loss in a separator with metal foam is reported. In this method, a metal foam is modeled as a porous media having homogenized permeability and inertial resistance coefficients. The permeability and inertial resistance coefficients were obtained by a numerical method that was validated by experimental data from a literature. Then the pressure drop in the separator with metal foam replaced by porous media was efficiently simulated under different working conditions, and the results were analyzed. It was found that the porous media had a great effect on the pressure drop in the separator. As pores per inch (PPI) and rotating speed increase and porosity decreases, the pressure drop of the separator increases. The results indicate that replacing metal foam by porous media is effective and simulating the pressure drop is feasible and effective in a separator with metal foam.

scholarly journals Experimental study of the pressure loss in aero-engine air-oil separators

2017 ◽  
Vol 121 (1242) ◽  
pp. 1147-1161 ◽  
Author(s):  
A. Laura Cordes ◽  
B. Tim Pychynski ◽  
C. Corina Schwitzke ◽  
D. Hans-Jörg Bauer ◽  
A. Thiago P. de Carvalho ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rotational Speed ◽  
Pressure Loss ◽  
Metal Foam ◽  
Separation Efficiency ◽  
Air Mass ◽  
Aero Engine

ABSTRACTThe results of extensive experimental testing of an aero-engine air-oil separator are presented and discussed. The study focuses on the pressure loss of the system. Oil enters the device in the form of dispersed droplets. Subsequently, separation occurs by centrifuging larger droplets towards the outer walls and by film formation at the inner surface of a rotating porous material, namely an open-cell metal foam. The work described here is part of a study led jointly by the Karlsruhe Institute of Technology (KIT) and the University of Nottingham (UNott) within a recent EU project.The goal of the research is to increase the separation efficiency to mitigate oil consumption and emissions, while keeping the pressure loss as low as possible. The aim is to determine the influencing factors on pressure loss and separation efficiency. With this knowledge, a correlation can eventually be derived. Experiments were conducted for three different separator configurations, one without a metal foam and two with metal foams of different pore sizes. For each configuration, a variety of engine-like conditions of air mass flow rate, rotational speed and droplet size was investigated. The experimental results were used to validate and improve the numerical modelling.Results for the pressure drop and its dependencies on air mass flow rate and the rotational speed were analysed. It is shown that the swirling flow and the dissipation of angular momentum are the most important contributors to the pressure drop, besides the losses due to friction and dissipation caused by the flow passing the metal foam. It was found that the ratio of the rotor speed and the tangential velocity of the fluid is an important parameter to describe the influence of rotation on the pressure loss. Contrary to expectations, the pressure loss is not necessarily increased with a metal foam installed.

Air Splits Research of Multi-Sector Combustor With Flow Network Approach and Experiments

2019 ◽  
Author(s):  
Shanping Shen ◽  
Guoqian Song
Keyword(s):  
Pressure Drop ◽  
Pressure Loss ◽  
Effective Area ◽  
Network Approach ◽  
Test Rig ◽  
Flow Network ◽  
Wide Range ◽  
Aero Engine ◽  
Annular Combustor ◽  
Good Agreement

Abstract Multi-sector combustor tests are essential to aero-engine annular combustor development. For the test rig design, it is necessary to ensure that the pressure drop and flow split to the various portions of multi-sector combustor are consistent with the combustor component. This paper introduces a new kind of multi-sector combustor rig. The diffuser system of the test rig is different with the combustor component. This test rig is simple in structure and easy to machine. To evaluate the flow split and pressure drop of the test rig, a 1D-flow network approach is applied to multi-sector combustor rig design. The calculated results show good agreement with the experiment data. In order to study whether the test rig can simulate flow split and pressure loss of combustor components, flow split and pressure loss under different design features are analyzed. Result shows that by changing the effective area of inner/outer annular inlet baffle and inner/outer bleed air plate, inner/outer liner pressure drop and the ratio of air flow to W31c can be changed in a wide range. Thus, this kind of multi-sector combustor rig is convenient to change the multi-sector combustor test rig design to meet the requirements of the pressure drop and flow split design of combustor component, even when the rig has been manufactured.

Limitations of a State-of-the-Art Numerical Modelling Framework for Two-Phase Flow in Aero-Engine Air/Oil Separators

2016 ◽  
Author(s):  
Thiago Piazera de Carvalho ◽  
Hervé P. Morvan ◽  
David Hargreaves ◽  
Laura Cordes ◽  
Corina Höfler
Keyword(s):  
Pressure Drop ◽  
Numerical Modelling ◽  
Metal Foam ◽  
State Of The Art ◽  
Air Flow ◽  
Metal Foams ◽  
Qualitative Assessment ◽  
Shaft Speed ◽  
Modelling Framework ◽  
Aero Engine

The development and limitations of a numerical modelling framework applied to an aero-engine air/oil separator are presented here. Oil enters the device in the form of dispersed droplets and primary separation occurs by centrifuging larger droplets towards the outer walls, whereas secondary separation occurs by partially coalescing and centrifuging smaller droplets within a porous material, namely an open-cell metal foam. The work described here is part of a study led jointly by the University of Nottingham (UNott) and the Karlsruhe Institute of Technology (KIT) in the Engine Breakthrough Components and Subsystems (E-BREAK) project. The main objectives for UNott have been to define a CFD methodology able to provide an accurate representation of the air flow behaviour and a qualitative assessment of the oil capture within the air/oil separator. The feasibility of using the current state-of-the-art modelling framework is assessed. Experimental measurements of the overall pressure drop and oil capture performed at KIT are used to validate the simulations. The methodology presented here overcomes some limitations and simplifications present in previous studies. A novel macroscopic model for the secondary oil separation phenomena within metal foams is presented. Experiments and simulations were conducted for three different separator configurations, one without a metal foam, and two with metal foams of different pore sizes. For each configuration, a variation of air flow, shaft speed and droplet size was conducted. The focus was on the separation of droplets with a diameter smaller than 10 μm. Single-phase air flow simulation results showed that overall pressure drop increases with both increased shaft speed and air flow, largely in agreement with the experiments. Oil capture results proved to be more difficult to be captured by the numerical model. One of the limitations of the modelling set-up employed here is not capable of capturing droplet re-entrainment due to accumulation of oil inside the metal foam, which is believed to play a significant role in the separation phenomena.

Two dimensional numerical modeling of a membrane humidifier with porous media flow field for PEM fuel cell

2015 ◽  
Vol 26 (06) ◽  
pp. 1550061 ◽  
Author(s):  
Ebrahim Afshari ◽  
Nasser Baharlou Houreh
Keyword(s):  
Porous Media ◽  
Pressure Drop ◽  
Flow Field ◽  
Metal Foam ◽  
Low Cost ◽  
Porous Metal ◽  
Dew Point ◽  
Porous Media Flow ◽  
Two Dimensional ◽  
Flow Rates

A membrane humidifier with porous media flow field (metal foam) can provide more water transfer, low manufacturing complexity and low cost in comparison with the conventional humidifier. In this study, a two-dimensional numerical model is developed to investigate the performance of the humidifier with porous metal foam. The results indicate that the dew point increases with a decrease in the permeability, but at permeabilities lower than 10-8 the pressure drop increases extremely. At all ranges of pressures, temperatures and flow rates of humidifier inlet, the pressure drop in humidifier with porous media flow field is only about 0.5 kPa higher than that of the conventional humidifier, which is not significant and it can be ignored. An increase in the pressure at dry side inlet and wet side inlet of the humidifier results in a better humidifier performance. Humidifier performs better at high flow rates and temperatures of humidifier wet side inlet. At all ranges of pressures, flow rates and temperatures humidifier with porous metal foam indicates better performance.

Heat Exchangers for Aero Engine Applications

2006 ◽  
Author(s):  
Kyros J. Yakinthos ◽  
Dimitris K. Missirlis ◽  
Achilles C. Palikaras ◽  
Apostolos K. Goulas
Keyword(s):  
Porous Media ◽  
Pressure Drop ◽  
Mass Flow ◽  
Heat Exchangers ◽  
Exhaust Gas ◽  
Cfd Modelling ◽  
Pressure Losses ◽  
Exhaust Duct ◽  
Aero Engine ◽  
Increased Pressure

Nowadays, the needs for safer, cleaner and more affordable civil aero engines are of increasing importance. To cover these needs, a technology for an advanced aero engine design, which uses an alternative thermodynamic cycle, has been presented. The basis of this cycle lies in the integration of a system of heat exchangers installed in the exhaust nozzle of the aircraft engine. The heat exchangers are operating as heat recuperators, exploiting the thermal energy of the turbine exhaust gas to pre-heat the compressor outlet air before combustion and, thus, resulting in reduced pollutants and decreased fuel consumption. In this work, a procedure for the optimization of this installation is presented. The minimization of the pressure losses on the exhaust gas side is chosen as the optimization criterion of this effort. The optimization is based on experimental measurements in laboratory conditions and 2D CFD modelling for the flow inside the exhaust duct and through the heat exchangers. Detailed measurements were carried out in order to derive the pressure drop law through one heat exchanger. This pressure drop law was used in a CFD approach where the heat exchangers were modelled as porous media with prescribed pressure drop. The accuracy of this pressure drop law was validated in comparison with experimental data for a wide range of inlet conditions. A 1:1 model of the quarter of the nozzle was constructed in a wind tunnel with four full-scale heat exchangers installed in the exhaust nozzle. The measurements proved the non-uniformity of the flow field, which resulted in increased pressure losses for the heat exchangers that were operating with increased mass flow. It was possible to make improvements in the nozzle installation in order to optimize the mass flow balance through the heat exchangers and minimize the pressure losses. The optimization was based on 2D CFD modelling for the flow inside the exhaust duct and through the heat exchangers. The adopted porous media model modelled the presence of the heat exchangers inside the nozzle. The CFD modelling proved sufficient in predicting the main flow field phenomena, which were responsible for the non-uniform distribution of the mass flow and the increased pressure losses. Then, modifications in the nozzle geometry and the heat exchangers orientations were implemented in the CFD modelling. These modifications proved that with a careful approach, a better arrangement of the heat exchangers could be achieved.

Derivation of an Anisotropic Model for the Pressure Loss Through a Heat Exchanger for Aero Engine Applications

2009 ◽  
Author(s):  
Kyros Yakinthos ◽  
Stefan Donnerhack ◽  
Dimitrios Missirlis ◽  
Olivier Seite ◽  
Paul Storm
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Pressure Loss ◽  
Pollutant Emissions ◽  
Experimental Measurements ◽  
Loss Model ◽  
Aero Engine ◽  
Porosity Model

We present an effort to model the pressure loss together with the heat transfer mechanism, in a heat exchanger designed for an integrated recuperative aero engine. The operation of the heat exchanger is focusing on the exploitation of the thermal energy of the turbine exhaust gas to pre-heat the compressor outlet air before combustion and to decrease fuel consumption and pollutant emissions. Two basic parameters characterize the operation of the heat exchanger, the pressure loss and the heat transfer. The derivation of the pressure loss model is based on experimental measurements that have been carried-out on a heat exchanger model. The presence of the heat exchanger is modeled using the concept of a porous medium, in order to facilitate the computational modeling by means of CFD. As a result, inside the integrated aero engine, the operation of the heat exchanger can be sufficiently modeled as long as a generalized and accurate pressure drop and heat transfer model is developed. Hence, the porosity model formulation should be capable of properly describing the overall macroscopic hydraulic and thermal behavior of the heat exchanger. The effect of the presence of the heat exchanger on the flow field is estimated from experimental measurements. For the derivation of the porous medium pressure loss model, an anisotropic formulation of a modified Darcy-Forchheimer pressure drop law is proposed in order to take into account the effects of the three-dimensional flow development through the heat exchanger. The heat transfer effects are taken also into account with the use of a heat transfer coefficient correlation. The porosity model is adopted by the CFD solver as an additional source term. The validation of the proposed model is performed through CFD computations, by comparing the predicted pressure drop and heat transfer with available experimental measurements carried-out on the heat exchanger model.

scholarly journals Equivalent Parallel Strands Modeling of Highly-Porous Media for Two-Dimensional Heat Transfer: Application to Metal Foam

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6308
Author(s):  
Nihad Dukhan
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Pressure Drop ◽  
Geometric Modeling ◽  
Metal Foam ◽  
Complex Structure ◽  
Computational Time ◽  
Two Dimensional ◽  
Simple Geometry ◽  
Highly Porous

A new geometric modeling of isotropic highly-porous cellular media, e.g., open-cell metal, ceramic, and graphite foams, is developed. The modelling is valid strictly for macroscopically two-dimensional heat transfer due to the fluid flow in highly-porous media. Unlike the current geometrical modelling of such media, the current model employs simple geometry, and is derived from equivalency conditions that are imposed on the model’s geometry a priori, in order to ensure that the model produces the same pressure drop and heat transfer as the porous medium it represents. The model embodies the internal structure of the highly-porous media, e.g., metal foam, using equivalent parallel strands (EPS), which are rods arranged in a spatially periodic two-dimensional pattern. The dimensions of these strands and their arrangement are derived from equivalency conditions, ensuring that the porosity and the surface area density of the model and of the foam are indeed equal. In order to obtain the pressure drop and heat transfer results, the governing equations are solved on the geometrically-simple EPS model, instead of the complex structure of the foam. By virtue of the simple geometry of parallel strands, huge savings on computational time and cost are realized. The application of the modeling approach to metal foam is provided. It shows how an EPS model is obtained from an actual metal foam with known morphology. Predictions of the model are compared to experimental data on metal foam from the literature. The predicted local temperatures of the model are found to be in very good agreement with their experimental counterparts, with a maximum error of less than 11%. The pressure drop in the model follows the Forchheimer equation.

Study on the pressure drop of crude oil-water with surfactant flow in porous media

2021 ◽  
pp. 1-7
Author(s):  
Huijun Zhao ◽  
Xiang Ding ◽  
Pengfei Yu ◽  
Yun Lei ◽  
Xiaofei Lv ◽  
...  
Keyword(s):  
Porous Media ◽  
Pressure Drop ◽  
Crude Oil ◽  
Flow In Porous Media ◽  
Oil Water

scholarly journals Numerical Study of Thermal-Hydraulic Performance of a New Spiral Z-Type PCHE for Supercritical CO2 Brayton Cycle

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4417
Author(s):  
Tingting Xu ◽  
Hongxia Zhao ◽  
Miao Wang ◽  
Jianhui Qi
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Pressure Loss ◽  
Numerical Study ◽  
Hydraulic Performance ◽  
Optimal Structure ◽  
Original Structure ◽  
Brayton Cycle ◽  
Compact Structure ◽  
Spiral Angle

Printed circuit heat exchangers (PCHEs) have the characteristics of high temperature and high pressure resistance, as well as compact structure, so they are widely used in the supercritical carbon dioxide (S-CO2) Brayton cycle. In order to fully study the heat transfer process of the Z-type PCHE, a numerical model of traditional Z-type PCHE was established and the accuracy of the model was verified. On this basis, a new type of spiral PCHE (S-ZPCHE) is proposed in this paper. The segmental design method was used to compare the pressure changes under 5 different spiral angles, and it was found that increasing the spiral angle θ of the spiral structure will reduce the pressure drop of the fluid. The effects of different spiral angles on the thermal-hydraulic performance of S-ZPCHE were compared. The results show that the pressure loss of fluid is greatly reduced, while the heat transfer performance is slightly reduced, and it was concluded that the spiral angle of 20° is optimal. The local fluid flow states of the original structure and the optimal structure were compared to analyze the reason for the pressure drop reduction effect of the optimal structure. Finally, the performance of the optimal structure was analyzed under variable working conditions. The results show that the effect of reducing pressure loss of the new S-ZPCHE is more obvious in the low Reynolds number region.

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