Aerodynamic Performance Prediction of a Profile in Ground Effect With and Without a Gurney Flap

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Carlo Cravero
Keyword(s):  
Experimental Data ◽  
Flow Distribution ◽  
Ground Effect ◽  
Numerical Approach ◽  
Aerodynamic Performance ◽  
Suction Surface ◽  
Gurney Flap ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance ◽  
Race Cars

A very detailed experimental case of a reversed profile in ground effect has been selected in the open literature where available experimental data have been used as reference data for the computational fluid dynamics (CFD) analysis. The CFD approach has been used to predict aerodynamic performance of the profile at different distances with respect to the ground: in the freestream case, there is no ground effect whereas in the low height the profile operation is limited by the stall on the suction surface. Moreover, the effect of a Gurney flap addition on flow distribution and performance has been numerically investigated. The experimental data have been used to setup and test the capabilities of the computational approach. With the addition of a Gurney flap, a significant flow unsteadiness is introduced that needs to be considered in the numerical approach. In this case, the configurations investigated are used to highlight the capabilities of CFD using Reynolds-averaged Naiver–Stokes (RANS) approach for its effective application as a tool for the detailed design of aerodynamic components to generate downforce for race cars.

Aerodynamic Performance Prediction of a Profile in Ground Effect

2014 ◽  
Author(s):  
Carlo Cravero
Keyword(s):  
Experimental Data ◽  
Performance Prediction ◽  
Reference Data ◽  
Ground Effect ◽  
Aerodynamic Performance ◽  
The Other ◽  
Cfd Analysis ◽  
Suction Surface ◽  
Source Codes ◽  
Commercial Code

A very detailed experimental case of a reversed profile in ground effect has been selected in the open literature and the available experimental data have been used as reference data for CFD analysis. The CFD approach has been used to predict the aerodynamic performance of the profile at different heights with respect to the ground: from the freestream case (no ground effect) to a low height where the stall on the suction surface limits the profile operation. Different CFD codes have been used starting with a well-known commercial code to different open source codes. The set of analysis with the commercial code has allowed the setup of the mesh to have the best accuracy from the simulations. The same grids have been used for the other codes in order to directly compare the solver properties without mesh influence. The results obtained by the codes are compared and discussed.

Numerical Simulation of the Flow Field for Rotor Ventilation System of Large-Scale Nuclear Power Turbo-Generator

2012 ◽  
Vol 152-154 ◽  
pp. 1498-1504 ◽  
Author(s):  
Xiao Hu Zhang ◽  
Lei Hu ◽  
Jian Hua Yuan ◽  
Yi Chao Yuan
Keyword(s):  
Flow Field ◽  
Nuclear Power ◽  
Large Scale ◽  
Ventilation System ◽  
Flow Distribution ◽  
Basic Unit ◽  
Turbo Generator ◽  
Key Issues ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance

The nuclear power turbo-generator with large capacity is a basic unit of nuclear power plant, while the cooling technology becomes one of the key issues which affect its design and operation deeply. Axial-radial ventilation structure for rotor is commonly used in large nuclear power generator. In this article, according to the basic principles of computational fluid dynamics (CFD), ventilation’s structure and performance is analyzed, 3D flow model is also established. After the boundary conditions are determined, the numerical calculation and analysis is finished. And then, the rules of flow distribution is obtained, the flow field and the static pressure character of the gap is also computed, which could be very important to the ventilation system of the whole generator.

Affinity Law Modified to Predict the Pump Head Performance for Different Viscosities Using the Morrison Number

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Abhay Patil ◽  
Gerald Morrison
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Flow Coefficient ◽  
Design Parameters ◽  
Sharp Change ◽  
Fluid Viscosity ◽  
Pump Head ◽  
Laminar And Turbulent Flow ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance

The goal of this study is to provide pump users a simple means to predict a pump's performance change due to changing fluid viscosity. During the initial investigation, it has been demonstrated that pump performance can be represented in terms of the head coefficient, flow coefficient, and rotational Reynolds number with the head coefficient data for all viscosities falling on the same curve when presented as a function of ф*Rew−a. Further evaluation of the pump using computational fluid dynamics (CFD) simulations for wider range of viscosities demonstrated that the value of a (Morrison number) changes as the rotational Reynolds number increases. There is a sharp change in Morrison number in the range of 104<Rew<3*104 indicating a possible flow regime change between laminar and turbulent flow. The experimental data from previously published literature were utilized to determine the variation in the Morrison number as the function of rotational Reynolds number and specific speed. The Morrison number obtained from the CFD study was utilized to predict the head performance for the pump with known design parameters and performance from published literature. The results agree well with experimental data. The method presented in this paper can be used to establish a procedure to predict any pump's performance for different viscosities; however, more data are required to completely build the Morrison number plot.

Navier–Stokes Analysis of Turbine Blade Heat Transfer and Performance

1992 ◽  
Vol 114 (4) ◽  
pp. 795-806 ◽  
Author(s):  
D. J. Dorney ◽  
R. L. Davis
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Aerodynamic Performance ◽  
Navier Stokes ◽  
Approximate Factorization ◽  
Absolute Level ◽  
Flow Angle ◽  
And Performance

A three-dimensional Navier–Stokes analysis of heat transfer and aerodynamic performance is presented for a low-speed linear turbine cascade. The numerical approach used in this analysis consists of an alternate-direction, implicit, approximate-factorization, time-marching technique. An objective of this investigation has been to establish the computational grid density requirements necessary to predict blade surface and endwall heat transfer accurately, as well as the exit plane aerodynamic total pressure loss and flow angle distributions. In addition, a study has been performed to determine the importance of modeling transition as well as a viable implementation strategy for the three-dimensional turbulence model in the turbine blade passage. Results are presented demonstrating that the present procedure can accurately predict three-dimensional turbine blade heat transfer as well as the absolute level and spanwise distribution of aerodynamic performance quantities.

Impact Investigation on the Aerodynamic Performance for Seal Leakage at the Stator Root of Multistage Axial Compressor

2020 ◽  
Author(s):  
Qi Wang ◽  
Lanxue Ren ◽  
Zhou Zhang ◽  
Ting Wang ◽  
Mingcong Luo
Keyword(s):  
Numerical Model ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Compressor ◽  
Flow Distribution ◽  
Numerical Approach ◽  
Aerodynamic Performance ◽  
The Impact ◽  
Multistage Axial Compressor

Abstract This paper presents a numerical model based on the mass flow rate of seal leakage. This numerical model is considered as a correct method for 3-D numerical simulation. It can be used to simulate the effect of seal leakage at the stator root of a multistage axial compressor. Implementation of the correct method is using a numerical model based on the flux conservation which can control the mass flow rate of seal leakage accurately at the seal cavity of compressor. The mass flow rate of seal leakage is chosen as the key research parameter on the aerodynamic performance effect of the seal engineering application in a multistage axial compressor. Combined with the 3-D numerical simulation methods, an engineering numerical approach is set up in this study. A nine-stage axial compressor is taken as the research object in this paper and its aerodynamic performance is tested for proving the applicability of the numerical model for seal leakage. In the cases of several operating rotation speeds, numerical results of the nine-stage axial compressor performance characteristic curves are in good agreement with the experimental data. It is considered that the numerical approach based on the simplified numerical model in this paper can predict the performance of multistage axial compressor accurately. Then, comparisons are made against different cases of seal leakage mass flow rate for analyzing the impact of seal leakage increasing on the aerodynamic performance of the nine-stage axial compressor. The main point of comparisons is focused on the changes of the overall performance and the flow distribution in the compressor with the seal leakage changing. The results indicate that performance of multistage axial compressor is degenerated faster and faster with seal leakage increasing in all operating working points. An overall decline is appeared in the flow capacity, working capacity, efficiency and surge margin of the compressor. For the impact investigation on the changes of flow distribution, the total pressure loss coefficient, the relative Mach number contours and the movement of streamlines are studied in different seal leakage cases under several operating working points. The result also shows that stators located in front stages of multistage axial compressor are affected more seriously with the increasing mass flow rate of seal leakage. Under the influence of seal leakage, degradation of flow condition in stators located in front stages is more severely than that in back stages, the total pressure loss coefficient and entropy are increased, and the flow separations at the root of stators in front stages are developed faster with seal leakage increasing. So it can be confirmed that relatively larger flow losses in front stages bring significant impact on the decay of aerodynamic performance for a multistage axial compressor.

A Numerical Study of Correlation Between Recirculation Length and Shedding Frequency in Vortex Shedding Phenomena

2021 ◽  
Vol 16 ◽  
pp. 48-62
Author(s):  
Carlo Cravero ◽  
Nicola Marogna ◽  
Davide Marsano
Keyword(s):  
Vortex Shedding ◽  
Numerical Study ◽  
Ground Effect ◽  
Reynolds Numbers ◽  
Numerical Approach ◽  
Test Case ◽  
Flow Characterization ◽  
Gurney Flap ◽  
High Reynolds ◽  
Recirculation Length

The purpose of this paper is to characterize and to estimate the recirculating length behind an aerodynamic profile in ground effect with Gurney Flap. The flow characterization at high Reynolds numbers was performed by means of numerical analysis. A correlation between the size of the recirculation length and the frequency of vortex shedding was studied. The vortex shedding has a characteristic frequency, which, in this work, is correlated to the size of a recirculation length defined by the authors. The numerical investigation methodology applied to the profile with Gurney Flap, was previously developed on the well-documented test case of the flow around a cylinder at high Reynolds. The case was chosen to investigate and to validate the numerical approach with experimental data.

Transient Study of the Cooling Process of a Small Cabinet

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
J. Arturo Alfaro-Ayala ◽  
J. J. Ramírez-Minguela ◽  
A. Gallegos-Muñoz ◽  
D. Hernández-Fusilier ◽  
J. M. Belman-Flores
Keyword(s):  
Experimental Data ◽  
Transient Temperature ◽  
Insulation Material ◽  
Cooling Process ◽  
Operational Conditions ◽  
Biological Matter ◽  
Computational Fluid Dynamics Cfd ◽  
Transient Study ◽  
And Performance ◽  
Relative Errors

Abstract A transient study of the cooling process inside a cabinet is presented in this work. Computational fluid dynamics (CFD) is used to obtain the transient temperature of the air inside a small cabinet. Three cooling levels, named Case 1, Case 2, and Case 3, were studied under different lapses of time and operational conditions. The temperature of the evaporator plate and the temperature of the room change with time through the implementation of user-defined functions (UDFs). The buoyancy effects that occur inside the cabinet (natural convection) were modeled using the approximation of all the properties fitted to temperature polynomials (PFTP). The transient temperature of the air inside the cabinet was obtained, until the second ON/OFF stage is reached, for the three cases studied. The prediction of the transient temperature of the air inside the small cabinet was validated with experimental data. The average relative errors of the transient temperatures of the air inside the cabinet were 0.49%, 0.19%, and 0.13% for Case 1, Case 2, and Case 3, respectively. The behavior of the temperature and velocity distributions of the air inside the cabinet for the ON and OFF stages is obtained. Finally, a better range of the temperature for the preservation of food, medicines, and biological matter is obtained with an increase in the thickness of the insulation material. An increment of 14.9% of the removed energy was obtained inside the cabinet with 12 cm of the insulation material, and this increment is related to the case with no insulation material. The results of this work could help in improving the design and performance of the cabinets in further works.

Aerodynamic Design of High End Wall Angle Turbine Stages—Part II: Experimental Verification

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
A. W. Cranstone ◽  
G. Pullan ◽  
E. M. Curtis ◽  
S. Bather
Keyword(s):  
Turbulence Modeling ◽  
Test Results ◽  
Suction Surface ◽  
Wall Angle ◽  
Computational Fluid Dynamics Cfd ◽  
The Difference ◽  
And Performance ◽  
Turbine Design ◽  
End Wall ◽  
Very High

An experimental investigation of a turbine stage featuring very high end wall angles is presented. The initial turbine design did not achieve a satisfactory performance and the difference between the design predictions and the test results was traced to a large separated region on the rear suction-surface. To improve the agreement between computational fluid dynamics (CFD) and experiment, it was found necessary to modify the turbulence modeling employed. The modified CFD code was then used to redesign the vane, and the changes made are described. When tested, the performance of the redesigned vane was found to have much closer agreement with the predictions than the initial vane. Finally, the flowfield and performance of the redesigned stage are compared to a similar turbine, designed to perform the same duty, which lies in an annulus of moderate end wall angles. A reduction in stage efficiency of at least 2.4% was estimated for the very high end wall angle design.

Aeroacoustics and Performance Modeling of a Counter-Rotating Propfan

2010 ◽  
Author(s):  
Martin Olausson ◽  
Richard Avella´n ◽  
Niklas So¨rman ◽  
Filip Rudebeck ◽  
Lars-Erik Eriksson
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Performance Modeling ◽  
Design Method ◽  
Preliminary Design ◽  
Propeller Design ◽  
Noise Evaluation ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance ◽  
The Ideal

This paper presents a method for design and analysis of counter-rotating propfans with respect to performance and aeroacoustics. The preliminary design method generates the ideal optimum propeller design corrected for losses in terms of profile and compressibility drag. The propeller design is further analyzed by computational fluid dynamics, CFD, to calculate the performance and the deterministic interaction noise. The unsteady flow around the propellers is calculated using URANS such that only one blade per propeller needs to be discretized. The unsteady pressure distribution around the blades is integrated, using a Ffowcs Williams-Hawkings method, to an observer for noise evaluation. The results of the performance analysis, the CFD computations and the aeroacoustic analysis are compared with experimental data available from the nonproprietary reports regarding the counter-rotating propellers developed in the 1980s.

NUMERICAL ANALYSIS OF CHEST FREEZER'S CONDENSING UNIT

2014 ◽  
Vol 22 (04) ◽  
pp. 1450028 ◽  
Author(s):  
PUSHPAK DOIPHODE ◽  
MANDAR TENDOLKAR ◽  
PATRIC ANANDA BALAN ◽  
INDRANEEL SAMANTA
Keyword(s):  
Fluid Dynamics ◽  
Air Flow ◽  
Flow Distribution ◽  
High Energy ◽  
Food Storage ◽  
Performance Effect ◽  
Tool Performance ◽  
Energy Consuming ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance

Chest freezers are high energy consuming refrigeration systems generally used for food storage. In a chest freezer, components such as condenser coil and fan, compressor, expansion device, etc. are placed at one corner of freezer and are covered by grills. All these components together are referred as condensing unit. Position of grills with respect to these components plays an important role in air flow distribution over condenser coil. Present work deals with the study of air flow distribution in condensing unit using Computational Fluid Dynamics (CFD) tool. Performance of the condenser is analyzed using CoilDesigner®. It is found that some air enters from side grill and bypasses the condenser coil without producing any condensing effect, resulting in degradation of performance. Effect of complete blockage of some portion of side grill on air flow distribution over condenser coil and performance of condenser is presented. Quantity of air flowing over condenser coil measured as Cubic Feet per Minute (CFM) and condenser capacity are found to be increased by approximately 10% and 2%, respectively.

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