scholarly journals Determination of the isentropic turbine efficiency due to adiabatic measurements and the validation of the conditions via a new criterion

2016 ◽  
Vol 232 (24) ◽  
pp. 4485-4494 ◽  
Author(s):  
R Zimmermann ◽  
R Baar ◽  
C Biet
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Boundary Conditions ◽  
Measuring Equipment ◽  
Turbine Efficiency ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
New Criterion

The determination of the isentropic turbine efficiency under adiabatic and SAE boundary conditions is studied in this paper. The study is structured into two parts. The first part describes the possibility of measuring the isentropic turbine efficiency directly. Normally this is not possible in measurements conducted following the SAE J922 guidelines. Therefore, the experiments have been carried out under adiabatic conditions, and combined with improved measuring equipment. The results were compared with adiabatic computational fluid dynamics simulations of this turbocharger. In the second part, a new criterion is defined in order to evaluate the quality of the adiabatic measurements and compare them with standard measurements. The investigation has been carried out with multiple turbochargers ranging from very small to medium passenger car size turbochargers. In the end, a possible application for the criterion is given.

scholarly journals COMPARISON OF AIRFLOW IN TYPE 36 LOW-INCOME HOUSING UNIT USING CFD SIMULATION

2021 ◽  
Vol 48 (2) ◽  
pp. 121-130
Author(s):  
Lestari Lestari ◽  
Syaiful Muazir
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Indoor Air ◽  
Low Income ◽  
Natural Ventilation ◽  
Cfd Simulation ◽  
Building Design ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Type 36 houses are built for people who have low income. Because of this, the buildings’ ventilation relies on natural airflow. One of the variables that affects natural ventilation is airflow. Airflow can affect the quality of indoor air, influencing the comfort and health of those within. This study aims to evaluate the designs of type 36 buildings from the perspective of the airflow through the unit. It uses computational fluid dynamics simulations to compare the pattern and velocity of airflow in each building design. There are six designs of type 36 house that have different layouts and placements of air vents. The results of the simulation and analysis show that rooms arranged in a way that allows for the placement of vents that were facing each other, even if they were in different rooms, generated continuous airflow without experiencing turbulence.

scholarly journals Aerodynamic analysis of uphill drafting in cycling

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
T. van Druenen ◽  
B. Blocken
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Scientific Literature ◽  
Sensitivity Analyses ◽  
Air Resistance ◽  
Wind Tunnel Measurements ◽  
Aerodynamic Effect ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

AbstractSome teams aiming for victory in a mountain stage in cycling take control in the uphill sections of the stage. While drafting, the team imposes a high speed at the front of the peloton defending their team leader from opponent’s attacks. Drafting is a well-known strategy on flat or descending sections and has been studied before in this context. However, there are no systematic and extensive studies in the scientific literature on the aerodynamic effect of uphill drafting. Some studies even suggested that for gradients above 7.2% the speeds drop to 17 km/h and the air resistance can be neglected. In this paper, uphill drafting is analyzed and quantified by means of drag reductions and power reductions obtained by computational fluid dynamics simulations validated with wind tunnel measurements. It is shown that even for gradients above 7.2%, drafting can yield substantial benefits. Drafting allows cyclists to save over 7% of power on a slope of 7.5% at a speed of 6 m/s. At a speed of 8 m/s, this reduction can exceed 16%. Sensitivity analyses indicate that significant power savings can be achieved, also with varying bicycle, cyclist, road and environmental characteristics.

scholarly journals Evaluation of Active Heat Sinks Design under Forced Convection—Effect of Geometric and Boundary Parameters

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2041
Author(s):  
Eva C. Silva ◽  
Álvaro M. Sampaio ◽  
António J. Pontes
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Additive Manufacturing ◽  
Pressure Drop ◽  
Forced Convection ◽  
Thermal Performance ◽  
Heat Sinks ◽  
Trapezoidal Shape ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

This study shows the performance of heat sinks (HS) with different designs under forced convection, varying geometric and boundary parameters, via computational fluid dynamics simulations. Initially, a complete and detailed analysis of the thermal performance of various conventional HS designs was taken. Afterwards, HS designs were modified following some additive manufacturing approaches. The HS performance was compared by measuring their temperatures and pressure drop after 15 s. Smaller diameters/thicknesses and larger fins/pins spacing provided better results. For fins HS, the use of radial fins, with an inverted trapezoidal shape and with larger holes was advantageous. Regarding pins HS, the best option contemplated circular pins in combination with frontal holes in their structure. Additionally, lattice HS, only possible to be produced by additive manufacturing, was also studied. Lower temperatures were obtained with a hexagon unit cell. Lastly, a comparison between the best HS in each category showed a lower thermal resistance for lattice HS. Despite the increase of at least 38% in pressure drop, a consequence of its frontal area, the temperature was 26% and 56% lower when compared to conventional pins and fins HS, respectively, and 9% and 28% lower when compared to the best pins and best fins of this study.

Sign in / Sign up

Export Citation Format

Share Document