scholarly journals Feasible Concept of an Air-Driven Fan with a Tip Turbine for a High-Bypass Propulsion System

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3350 ◽  
Author(s):  
Guoping Huang ◽  
Xin Xiang ◽  
Chen Xia ◽  
Weiyu Lu ◽  
Lei Li
Keyword(s):  
Fluid Dynamics ◽  
Carbon Dioxide Emissions ◽  
Three Dimensional ◽  
Propulsion System ◽  
Navier Stokes ◽  
Three Dimensional Flow ◽  
Low Pressure Turbine ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Bypass Ratio

The reduction in specific fuel consumption (SFC) is crucial for small/mid-size cost-controllable aircraft, which is very conducive to reducing cost and carbon dioxide emissions. To decrease the SFC, increasing the bypass ratio (BPR) is an important way. Conventional high-BPR engines have several limitations, especially the conflicting spool-speed requirements of a fan and a low-pressure turbine. This research proposes an air-driven fan with a tip turbine (ADFTT) as a potential device for a high-bypass propulsion system. Moreover, a possible application of this ADFTT is introduced. Thermodynamic analysis results show that an ADFTT can improve thrust from a prototype turbofan. As a demonstration, we selected a typical small-thrust turbofan as the prototype and applied the ADFTT concept to improve this model. Three-dimensional flow fields were numerically simulated through a Reynolds averaged Navier-Stokes (RANS)-based computational fluid dynamics (CFD) method. The performance of this ADFTT has the possibility of amplifying the BPR more than four times and increasing the thrust by approximately 84% in comparison with the prototype turbofan.

scholarly journals Numerical Investigations of a Tip Turbine Aerodynamic Design in a Propulsion System for VTOL Vehicles

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 3003
Author(s):  
Xin Xiang ◽  
Guoping Huang ◽  
Jie Chen ◽  
Lei Li ◽  
Weiyu Lu
Keyword(s):  
Three Dimensional ◽  
Propulsion System ◽  
Navier Stokes ◽  
Energy Extraction ◽  
Aerodynamic Design ◽  
High Reaction ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
High Thrust ◽  
Bypass Ratio

High thrust and low specific fuel consumption (SFC) are important for vertical takeoff and landing (VTOL) vehicles. An effective way to decrease the SFC is to increase the bypass ratio (BPR) of the propulsion system. The air-driven fan (or fan-in-wing) has a very high bypass ratio and has proved to be successful in VTOL aircrafts. However, the tip turbine that extracts energy for the air-driven fan faces the low-solidity problem and performs inadequately. In this study, we developed a high-reaction method for the aerodynamic design of a tip turbine to solve the low-solidity problem. A typical tip turbine was selected and designed by both conventional and high-reaction methods. Three-dimensional flow fields were numerically simulated through a Reynolds-averaged Navier-Stokes (RANS)-based computational fluid dynamics (CFD) method. The energy extraction rate was proposed to evaluate and display the energy extraction capability of the turbine. The results showed that the high-reaction turbine could solve the low-solidity problem and significantly increase the isentropic efficiency from approximately 80.0% to 85.6% and improve the isentropic work by 71.9% compared with the conventional method (from 10.28 kW/kg to 17.67 kW/kg).

scholarly journals Airflow inside the nasal cavity: visualization using computational fluid dynamics

2010 ◽  
Vol 4 (4) ◽  
pp. 657-661 ◽  
Author(s):  
Mohammed Zubair ◽  
Vizy Nazira Riazuddin ◽  
Mohammed Zulkifly Abdullah ◽  
Rushdan Ismail ◽  
Ibrahim Lutfi Shuaib ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Nasal Cavity ◽  
Three Dimensional ◽  
Clinical Importance ◽  
Navier Stokes ◽  
Tomographic Images ◽  
Computed Tomographic ◽  
Continuity Equations ◽  
Cfd Method

Abstract Background: It is of clinical importance to examine the nasal cavity pre-operatively on surgical treatments. However, there is no simple and easy way to measure airflow in the nasal cavity. Objectives: Visualize the flow features inside the nasal cavity using computational fluid dynamics (CFD) method, and study the effect of different breathing rates on nasal function. Method: A three-dimensional nasal cavity model was reconstructed based on computed tomographic images of a healthy Malaysian adult nose. Navier-Stokes and continuity equations for steady airflow were solved numerically to examine the inspiratory nasal flow. Results: The flow resistance obtained varied from 0.026 to 0.124 Pa.s/mL at flow-rate from 7.5 L/min to 40 L/min. Flow rates by breathing had significant influence on airflow velocity and wall shear-stress in the vestibule and nasal valve region. Conclusion: Airflow simulations based on CFD is most useful for better understanding of flow phenomenon inside the nasal cavity.

Numerical Simulation of the Laminar Flow Field in Stirred Tank with Double Layer Combined Impeller Stirring Eccentrically

2015 ◽  
Vol 779 ◽  
pp. 125-132
Author(s):  
Ying Na Liang
Keyword(s):  
Flow Field ◽  
Double Layer ◽  
Three Dimensional ◽  
Stirred Tank ◽  
Flow Structures ◽  
Practical Application ◽  
Three Dimensional Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Multiple Reference

Computational fluid dynamics (CFD) method was applied to study the flow field in cylindrical stirred tank mixing non-Newtonian fluid with double layer combined impeller of upper-straight-blade and lower-inclined-blade. The laminar model and the multiple reference frame (MRF) were employed to simulate the three-dimensional flow field in stirred tank with double layer combined impeller rotating at a constant speed of 200 r/min mixing the mixture of glycerin and water centrally、eccentrically and relative eccentrically, and three different flow structures in stirred tank were obtained. Analyzing the velocity vectors, the velocity contours and the axial、radial and tangent velocity distribution curves, the rule of velocity field with the blade combined form and the stirring structure was discussed. The research provided the valuable reference for the design and practical application of the laminar stirred tank.

scholarly journals ICCM2015: A Comparison of RANS and LES Computational Methods in Analyzing Ventilation Flow Through a Room Fitted with a Two-Sided Windcatcher

2017 ◽  
Vol 14 (03) ◽  
pp. 1750021 ◽  
Author(s):  
A. Niktash ◽  
B. P. Huynh
Keyword(s):  
Natural Ventilation ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Interior Space ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Cfd Method ◽  
Good Agreement

A windcatcher is a structure for providing natural ventilation using wind power; it is usually fitted on the roof of a building to exhaust the inside stale air to the outside and supplies the outside fresh air into the building interior space working by pressure difference between outside and inside of the building. In this paper, the behavior of free wind flow through a three-dimensional room fitted with a centered position two-canal bottom shape windcatcher model is investigated numerically, using a commercial computational fluid dynamics (CFD) software package and LES (Large Eddy Simulation) CFD method. The results have been compared with the obtained results for the same model but using RANS (Reynolds Averaged Navier–Stokes) CFD method. The model with its surrounded space has been considered in both method. It is found that the achieved results for the model from LES method are in good agreement with RANS method’s results for the same model.

Effect of Blade Numbers on Pressure Drop of Axial Cyclone Separators by CFD

2011 ◽  
Vol 55-57 ◽  
pp. 343-347 ◽  
Author(s):  
Yi Gang Luan ◽  
Hai Ou Sun
Keyword(s):  
Pressure Drop ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Three Dimensional Model ◽  
Navier Stokes Equations ◽  
Pressure Drops ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Resistance Performance

In this article, computational fluid dynamics(CFD) method is used to predict the effect of blade numbers on the pressure drop of axial cyclone separators. A three-dimensional model is built to acquire the resistance of axial cyclone separators with different blade numbers. The flow field inside cyclone separators is calculated using 3D Reynolds-averaged Navier-Stokes equations. And turbulence model is used to simulate the Reynold stress. Also pressure drop of cyclone separators with different blade numbers is expressed as a function of different inlet velocities. At the same inlet velocity with increasing the blade numbers, pressure drops of cyclones reduce greatly. And changing the blade number of cyclone separator is an effective method to improve its resistance performance.

Prediction of Particle Impact on an Archimedes Screw Runner Blade for Micro Hydro Turbine

2013 ◽  
Vol 465-466 ◽  
pp. 552-556
Author(s):  
Muhammad Ammar Nik Mutasim ◽  
Nurul Suraya Azahari ◽  
Ahmad Alif Ahmad Adam
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Navier Stokes ◽  
Particle Impact ◽  
Three Dimensional Flow ◽  
Navier Stokes Equation ◽  
Runner Blade ◽  
Computational Fluid Dynamics Cfd ◽  
The Subject ◽  
The Impact

Energy is one of the most important sources in the world especially for developing countries. The subject study is conducted to predict the behaviour of particle due to errosion from the river through the achimedes screw runner and predict the impact of particle toward blade surface. For this reason, computational fluid dynamics (CFD) methods are used. The three-dimensional flow of fluid is numerically analyzed using the Navier-Stokes equation with standard k-ε turbulence model. The reinverse design of archimedes screw blade was refered with the previous researcher. Flow prediction with numerical results such as velocity streamlines, flow pattern and pressure contour for flow of water entering the blade are discussed. This study shows that the prediction of particle impact occurs mostly on the entering surface blade and along the leading edge of the screw runner. Any modification on the design of the screw runner blade can be analyze for further study.

Influence of the Obliquity of Fin Ray on Propulsion Performance for Biorobotic Underwater Undulating Propulsor

2011 ◽  
Vol 52-54 ◽  
pp. 267-272 ◽  
Author(s):  
Yong Hua Zhang ◽  
Jian Hui He ◽  
Guo Qing Zhang
Keyword(s):  
Three Dimensional ◽  
Navier Stokes ◽  
Environment Friendly ◽  
Contour Maps ◽  
Propulsion Performance ◽  
Fin Ray ◽  
Propulsion Force ◽  
Computational Fluid Dynamics Cfd ◽  
Motion Performance ◽  
Cfd Method

This paper aims to understand influence of the obliquity of fin ray on its motion performance. An environment-friendly propulsion system mimicking undulating fins of stingray had been built. Investigations were presented by using three-dimensional unsteady Computational Fluid Dynamics (CFD) method. An unstructured, grid-based, unsteady Navier-Stokes solver with automatic adaptive remeshing was used to compute the unsteady flow around the fin through twenty complete cycles. The pressure distribution on fin surface was computed and integrated to provide fin forces which were decomposed into lift and thrust. Vortex contour maps of the fin with different obliquity of fin ray were displayed and compared. Finally, we draw a conclusion that the generated propulsion force of the biomimetic propulsor is gradually increase with the obliquity of the fin ray from 0 degree till a certain angle and then gradually decrease with the obliquity of the fin ray from the certain angle till 90 degree. The results provide valuable information for the optimization of robotic underwater undulating propulsor design.

Two-Phase CFD of Channel Boiling for Boiling Transition Problems

2014 ◽  
Author(s):  
Antonin Povolny ◽  
Martin Cuhra
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
First Principles ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Two Phase ◽  
General Ability ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Traditional Approaches

In order to ensure safety of nuclear installations, thermohydraulics has developed many ways how to predict the behavior of coolant in a heated boiling channel. Accuracy of these predictions can be improved using three-dimensional Computational Fluid Dynamics (CFD) method, which is based on first principles of fluid mechanics. Even though when using CFD, there is a struggle between the accuracy and low computation costs, in many cases CFD can provide feasible improvement of accuracy compared to more traditional approaches. In this research, the focus is set on channel boiling problems, especially those associated with boiling transitions. The phenomenon of critical heat flux (CHF) is investigated using two-phase CFD computation and is compared to experimental data. There is also comparison with other computation methods. When experiment provides some set of data, CFD calculation provides description of the whole flow behavior that provides significantly more information and is of great value during the design process when it gives the understanding of undergoing effects. Besides CHF, general ability of CFD to predict changes in boiling patterns in two-phase channel boiling flows is discussed.

scholarly journals VERIFICATION OF SCHRENK METHOD FOR WING LOADING ANALYSIS OF SMALL UNMANNED AIRCRAFT USING NAVIERSTOKES BASED CFD SIMULATION

2018 ◽  
Vol 15 (2) ◽  
pp. 161 ◽  
Author(s):  
Arifin Rasyadi Soemaryanto ◽  
Nurhayyan Halim Rosid
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Approximation Method ◽  
Cfd Simulation ◽  
Unmanned Aircraft ◽  
Navier Stokes ◽  
Aerodynamic Load ◽  
Wing Loading ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Prediction of an aerodynamic load acting on a wing or usually called wing loading becomes an important stage for structural analysis. Several methods have been used in estimating the wing loading. Schrenk approximation method is commonly used to achieve the fast estimation of lift distribution along wingspan, but in order to achieve a high level accuracy of aerodynamic prediction, computational fluid dynamics (CFD) with Navier Stokes-based equation can be used. LAPAN Surveillance UAV (LSU series) has been chosen to represent an aerodynamics analysis on generic small unmanned aircraft with twinboom vertical stabilizer configuration. This study was focused to verify the Schrenk approximation method using high accuracy numerical simulation (CFD). The goal of this study was to determine the lift distribution along wingspan and a number of errors between Schrenk approximation and CFD method. In this study, Schrenk approximation result showed similarity with the CFX simulation. So the two results have been verified in analysis of wing loading. ABSTRAKPrediksi dari beban aerodinamika yang terjadi pada sayap menjadi salah satu tahap yang penting dalam analisis struktur perancangan pesawat. Beberapa metode telah digunakan untuk mengestimasi besarnya beban aerodinamika pada sayap. Metode Schrenk umum digunakan untuk estimasi cepat perhitungan besar distribusi gaya angkat di sepanjang sayap. Guna mencapai tingkat akurasi yang tinggi dari prediksi aerodinamika, simulasi Computational Fluid Dynamics (CFD) dengan berbasis persamaan Navier-Stokes dapat digunakan. Pesawat nirawak LSU dipilih untuk merepresentasikan analisis aerodinamika pada pesawat nirawak dengan konfigurasi twin-tailboom pusher. Fokus dari studi yang dilakukan adalah untuk memverifikasi dari metode pendekatan dari Schrenk dengan menggunakan metode yang memiliki akurasi tinggi seperti simulasi CFD. Tujuan dari studi adalah untuk menghitung distribusi gaya angkat sepanjang sayap dan menentukan seberapa besar error dari kedua metode.

RANS Simulations of a Simplified Tractor/Trailer Geometry

2006 ◽  
Vol 128 (5) ◽  
pp. 1083-1089 ◽  
Author(s):  
Christopher J. Roy ◽  
Jeffrey Payne ◽  
Mary McWherter-Payne
Keyword(s):  
Vortical Structure ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Base Region ◽  
Near Wake ◽  
Three Dimensional Flow ◽  
Fine Mesh ◽  
Computational Fluid Dynamics Cfd ◽  
Rans Simulations ◽  
Yaw Angle

Steady-state Reynolds-averaged Navier-Stokes (RANS) simulations are presented for the three-dimensional flow over a simplified tractor/trailer geometry at zero degrees yaw angle. The simulations are conducted using a multi-block, structured computational fluid dynamics (CFD) code. The turbulence closure model employed is the two-equation Menter k-ω model. The discretization error is estimated by employing two grid levels: a fine mesh of 20 million cells and a coarser mesh of 2.5 million cells. Simulation results are compared to experimental data obtained at the NASA-Ames 7×10ft wind tunnel. Quantities compared include vehicle drag, surface pressures, and time-averaged velocities in the trailer near wake. The results indicate that the RANS approach is able to accurately predict the surface pressure on the vehicle, with the exception of the base region. The pressure predictions in the base region are poor due to the inability of the RANS model to accurately capture the near-wake vortical structure. However, the gross pressure levels in the base region are in reasonable agreement with experiment, and thus the overall vehicle drag is well predicted.

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