Measurement of temperature and flow field in cabin on natural convection

2015 ◽  
pp. 99-102 ◽  
Keyword(s):  
Natural Convection ◽  
Flow Field

Fundamental Issues and Recent Advancements in Analysis of Aircraft Brake Natural Convective Cooling

1998 ◽  
Vol 120 (4) ◽  
pp. 840-857 ◽  
Author(s):  
M. P. Dyko ◽  
K. Vafai
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Flow Field ◽  
Three Dimensional ◽  
Convective Cooling ◽  
Cooling Flow ◽  
Physical Mechanisms ◽  
Braking System ◽  
Flow And Heat Transfer ◽  
Convection Cooling

A heightened awareness of the importance of natural convective cooling as a driving factor in design and thermal management of aircraft braking systems has emerged in recent years. As a result, increased attention is being devoted to understanding the buoyancy-driven flow and heat transfer occurring within the complex air passageways formed by the wheel and brake components, including the interaction of the internal and external flow fields. Through application of contemporary computational methods in conjunction with thorough experimentation, robust numerical simulations of these three-dimensional processes have been developed and validated. This has provided insight into the fundamental physical mechanisms underlying the flow and yielded the tools necessary for efficient optimization of the cooling process to improve overall thermal performance. In the present work, a brief overview of aircraft brake thermal considerations and formulation of the convection cooling problem are provided. This is followed by a review of studies of natural convection within closed and open-ended annuli and the closely related investigation of inboard and outboard subdomains of the braking system. Relevant studies of natural convection in open rectangular cavities are also discussed. Both experimental and numerical results obtained to date are addressed, with emphasis given to the characteristics of the flow field and the effects of changes in geometric parameters on flow and heat transfer. Findings of a concurrent numerical and experimental investigation of natural convection within the wheel and brake assembly are presented. These results provide, for the first time, a description of the three-dimensional aircraft braking system cooling flow field.

Experimental and Numerical Study for Improved Understanding of Mixed-Convection Type of Flows in Turbine Casing Cavities During Shut-Down Regimes

2021 ◽  
Author(s):  
Oguzhan Murat ◽  
Budimir Rosic ◽  
Koichi Tanimoto ◽  
Ryo Egami
Keyword(s):  
Natural Convection ◽  
Flow Field ◽  
Mixed Convection ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Scale Model ◽  
Unsteady Temperature ◽  
Numerical Predictions ◽  
Wide Range ◽  
Turbine Casing

Abstract Due to increase in the power generation from renewable sources, steam and gas turbines will be required to adapt for more flexible operations with frequent start-ups and shut-downs to provide load levelling capacity. During shut-down regimes, mixed convection takes place with natural convection dominance depending on the operating conditions in turbine cavities. Buoyant flows inside the turbine that are responsible for non-uniform cooling leading to thermal stresses and compromise clearances directly limits the operational flexibility. Computational fluid dynamics (CFD) tools are required to predict the flow field during these regimes since direct measurements are extremely difficult to conduct due to the harsh operating conditions. Natural convection with the presence of cross-flow -mixed convection has not been extensively studied to provide detailed measurements. Since the literature lacks of research on such flows with real engine representative operating conditions for CFD validation, the confidence in numerical predictions is rather inadequate. This paper presents a novel experimental facility that has been designed and commissioned to perform very accurate unsteady temperature and flow field measurements in a simplified turbine casing geometry. The facility is capable of reproducing a wide range of Richardson, Grashof and Reynolds numbers which are representative of engine realistic operating conditions. In addition, high fidelity, wall resolved LES with dynamic Smagorinsky subgrid scale model has been performed. The flow field as well as heat transfer characteristics have been accurately captured with LES. Lastly, inadequacy of RANS for mixed type of flows has been highlighted.

scholarly journals Air-impingement freezing of peeled shrimp: Analysis of flow field, heat transfer, and freezing time

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983504 ◽  
Author(s):  
Dazhang Yang ◽  
Jing Xie ◽  
Wan Tang ◽  
Jinfeng Wang ◽  
Zhitao Shu
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Flow Field ◽  
Jet Flows ◽  
Freezing Process ◽  
Freezing Time ◽  
Air Jet ◽  
Food Freezing ◽  
Air Impingement ◽  
Set Up

The air-impingement freezing technique is a fast and efficient freezing method, which is widely used in food freezing and electronic industry. A novel air-impingement freezing machine was set up to investigate the food freeze. The freezing process of peeled shrimps by air-impingement freezing technique was studied experimentally and numerically. The freezing time of shrimp (150 count/lb) from +11°C to −18°C was about 100–140 s. The flow field and temperature distribution of peeled shrimp were studied by the solidification and melting model in FLUENT 6.3. The results show that the air jet flows away from the surface of the shrimp after the separation points so that the flow field and heat transfer were bad in the separation resign. In addition, the food freezing time of natural convection and air-impingement was compared, and the result shows that the air-impingement freezing time is about one-tenth than the natural convection freezing in freezer. In order to optimize the air-impingement freezing, H/D’s value was adjusted in the range of 4–8. The result indicates that the freezing time was increasing with the increase in H/D value, and H/D was recommended to be 6 in the impingement freezing.

Heat Transfer in Gas-Insulated Bus Bars

2003 ◽  
Author(s):  
Jin-Ki Ham ◽  
Young-Ki Kim ◽  
Jin-Soo Kim ◽  
Seok-Hyun Song
Keyword(s):  
Natural Convection ◽  
Flow Field ◽  
Heat Balance ◽  
Single Phase ◽  
Field Analysis ◽  
Balance Calculation ◽  
Three Phase ◽  
Flow Field Analysis ◽  
Laminar Natural Convection ◽  
The Heat Balance

Numerical prediction and experimental verification of the temperature rise for a single-phase and a three-phase gas-insulated bus bar with current flow are investigated. Various heat generation rates possibly produced in the gas-insulated bus bar are calculated. To estimate the power loss caused by eddy current, the magnetic field analysis is carried out. The heat balance calculation solving the differential form of an energy balance equation with empirical relations is conducted by using the 5th order Runge-Kutta method. The various cases representing different geometries and current values are investigated by conducting the heat balance calculation. Three-dimensional numerical flow field analysis using finite volume method is performed for the different type of the bus bars. From the flow field analysis based on laminar natural convection, the temperature gradient in the current flowing direction caused by contact heat source is found for both single-phase and three-phase bus bars. In the experiments, temperature rises in each of conductor, contact part, and external tank are measured for a full-scale gas-insulated bus bar. The comparisons of the predicted values of the heat balance calculation and the numerical analyses to results of the experiments are made. From the comparisons, it is concluded that the temperature rise of a bus bar can be predicted quite well by performing laminar natural convection flow analyses.

scholarly journals Natural Convection in a Trapezoidal Enclosure with Wavy Top Surface

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Pensiri Sompong ◽  
Supot Witayangkurn
Keyword(s):  
Natural Convection ◽  
Temperature Distribution ◽  
Flow Field ◽  
Element Model ◽  
Darcy Number ◽  
Model Builder ◽  
Small Influence ◽  
Study Results ◽  
Flow Intensity ◽  
Trapezoidal Enclosure

The effects of various parameters, Rayleigh number (Ra), Darcy number (Da), and wave amplitude (a), on natural convection inside a trapezoidal enclosure with wavy top surface are studied. The enclosure is filled with seawater having Prandtl number (Pr) of 7.2 and uniformly heated on bottom and partially heated on inclined boundaries. The flow field and temperature distribution are observed when interested parameters are chosen for Ra = 104, 105, and 106, Da = 10−5, 10−4, and 10−3, anda=0.9, 1, and 1.1. FlexPDE, a finite element model builder, is used to solve the governing equations to obtain the numerical results displayed by streamlines and isotherms. From the study results, convection motion is affected by different parameters in which the increase in flow intensity and temperature distribution can be seen at higher Rayleigh and Darcy numbers. The wavy top surface has small influence on the flow field and temperature distribution compared to the influence of Rayleigh and Darcy numbers.

Sign in / Sign up

Export Citation Format

Share Document