Uncertainty Quantification of Thermocouple Air Temperature Measurement in Highly Radiative Environment: Application to Turbofan Engine Compartment

2016 ◽  
Author(s):  
Y. Sommerer ◽  
V. Drouin ◽  
X. Nicolas ◽  
B. Trouette
Keyword(s):  
Heat Flux ◽  
Temperature Measurement ◽  
Air Temperature ◽  
Data Bank ◽  
Heat Shield ◽  
Engine Compartment ◽  
Heat Shields ◽  
Air Speed ◽  
Thermocouple Temperature ◽  
The Impact

This paper focuses on thermocouple air temperature measurement uncertainty due to the radiative fluxes present in the engine compartment where engine case skin temperature can exceed 900 K. To really measure air temperature, the convective heat flux in the thermocouple bead must be predominant. This is why heat shields are used in order to reduce the radiative heat flux on the bead. However, in engine compartment, the heat shield orientation must be optimized since numerous hot walls surround the thermocouple. In order to evaluate the impact of badly oriented heat shields and to provide a data bank for numerical simulation validations, a heated wind tunnel has been used. It has been shown that the uncertainty on the thermocouple temperature can reach dozens of degrees depending on the air speed and the heat shield orientation. Furthermore a specific 3D thermocouple model has been build and validated by comparison with the lab measurements. Then this thermocouple 3D model has been integrated in the whole engine compartment aero-thermal model in order to quantify the uncertainty of the thermocouple air temperature measurement in the real engine environment.

scholarly journals Seasonal Surface Air Temperature and Precipitation in the FSU Climate Model Coupled to the CLM2

2005 ◽  
Vol 18 (16) ◽  
pp. 3217-3228 ◽  
Author(s):  
D. W. Shin ◽  
S. Cocke ◽  
T. E. LaRow ◽  
James J. O’Brien
Keyword(s):  
Heat Flux ◽  
Air Temperature ◽  
Climate Model ◽  
Initial Conditions ◽  
Sensible Heat Flux ◽  
Surface Air Temperature ◽  
Community Land Model ◽  
Temperature And Precipitation ◽  
The Impact ◽  
Convective Scheme

Abstract The current Florida State University (FSU) climate model is upgraded by coupling the National Center for Atmospheric Research (NCAR) Community Land Model Version 2 (CLM2) as its land component in order to make a better simulation of surface air temperature and precipitation on the seasonal time scale, which is important for crop model application. Climatological and seasonal simulations with the FSU climate model coupled to the CLM2 (hereafter FSUCLM) are compared to those of the control (the FSU model with the original simple land surface treatment). The current version of the FSU model is known to have a cold bias in the temperature field and a wet bias in precipitation. The implementation of FSUCLM has reduced or eliminated this bias due to reduced latent heat flux and increased sensible heat flux. The role of the land model in seasonal simulations is shown to be more important during summertime than wintertime. An additional experiment that assimilates atmospheric forcings produces improved land-model initial conditions, which in turn reduces the biases further. The impact of various deep convective parameterizations is examined as well to further assess model performance. The land scheme plays a more important role than the convective scheme in simulations of surface air temperature. However, each convective scheme shows its own advantage over different geophysical locations in precipitation simulations.

scholarly journals Thermal history and comfort in a Brazilian subtropical climate: a 'cool' addiction hypothesis

2016 ◽  
Vol 16 (1) ◽  
pp. 7-20 ◽  
Author(s):  
Renata De Vecchi ◽  
Christhina Maria Cândido ◽  
Roberto Lamberts
Keyword(s):  
Air Temperature ◽  
Indoor Air ◽  
Thermal History ◽  
Air Conditioning ◽  
Prolonged Exposure ◽  
Temperature Fluctuations ◽  
Subtropical Climate ◽  
Indoor Thermal Comfort ◽  
Air Speed ◽  
The Impact

Abstract Currently, there is a rising trend for commercial buildings to use air conditioning to provide indoor thermal comfort. This paper focuses on the impact of prolonged exposure to indoor air-conditioned environments on occupants' thermal acceptability and preferences in a mixed-mode building in Brazil. Questionnaires were administered while indoor microclimatic measurements were carried out (i.e., air temperature, radiant air temperature, air speed and humidity). Results suggest significant differences in occupants' thermal acceptability and cooling preferences based on thermal history; differences were found between groups based on different physical characteristics (i.e., different gender and body condition). The findings also indicated a significant potential to implement temperature fluctuations indoors when occupants are exposed to air conditioning environments in warm and humid climates.

scholarly journals Evaluation of nature-based solutions implementation scenarios, using urban surface modelling

2021 ◽  
pp. 1-42
Author(s):  
Emmanuel Panagiotakis ◽  
Dionysia Kolokotsa ◽  
Nektarios Chrysoulakis
Keyword(s):  
Heat Flux ◽  
Relative Humidity ◽  
Urban Environment ◽  
Air Temperature ◽  
Green Infrastructure ◽  
Model Simulation ◽  
Meteorological Data ◽  
Sensible Heat Flux ◽  
The Impact ◽  
The City

The present paper aims to study the impact of Nature Based Solutions (NBS) on the urban environment. The Surface Urban Energy and Water balance Scheme (SUEWS) is used to quantify the impact of NBS in the city of Heraklion, Crete, Greece, a densely built urban area. Local meteorological data and data from an Eddy Covariance flux tower installed in the city center are used for the model simulation and evaluation. Five different scenarios are tested by replacing the city’s roofs and pavements with green infrastructure, i.e., trees and grass, and water bodies. The NBS impact evaluation is based on the changes of air temperature above 2m from the ground, relative humidity and energy fluxes. A decrease of the air temperature is revealed with the highest reduction (2.3%) occurring when the pavements are replaced with grass for all scenarios. The reduction of the air temperature is followed by a decrease in turbulent sensible heat flux. For almost all cases, an increase of the relative humidity is noticed, accompanied by a considerable increase of the turbulent latent heat flux. Therefore, NBS in cities change the energy balance significantly and modify the urban environment for the citizens' benefit.

scholarly journals CREATION OF MATHEMATICAL MODELS FOR PARAMETRIC IDENTIFICATION DURING TESTS TO DETERMINE THE FUEL CONSUMPTION OF THE HELICOPTER WITH EXHAUST- HEAT SHIELDS

2021 ◽  
pp. 134-139
Author(s):  
I. Televnyi
Keyword(s):  
Mathematical Models ◽  
Fuel Consumption ◽  
Basic Result ◽  
Parametric Identification ◽  
Careful Consideration ◽  
Heat Shield ◽  
Exhaust Heat ◽  
Infra Red ◽  
Heat Shields ◽  
The Impact

With the increasing effectiveness of guided missile weapons, the problem of protecting helicopters from these means of destruction is becoming increasingly important. To date, the issue of assessing the protection of helicopters in tests of helicopter equipment are insufficiently developed and require more careful consideration. Therefore, the research of the protection of helicopters equipped with an integrated protection system against guided missiles with infra-red target seeker devices and the impact of exhaust-heat shields on the values of flight characteristics of the helicopter is quite relevant. The article researches the influence of exhaust-heat shields on the flight technical characteristics of helicopters, their change during the installation of exhaust-heat shields. The estimation of the change in geometric, mass and center characteristics of helicopters by the calculation method is given and the method determining the characteristics of fuel consumption by the calculation and experimental method is given. The methodology and results of experimental researches of flight technical characteristics of the helicopter with the established exhaust-heat shield are described. The basic result of the research is the study of existing methods for determining the impact of exhaust-heat shields on the flight characteristics of helicopters. Methods of parametric identification for determination of fuel consumption are worked out and the analysis of flight technical characteristics of the helicopter is developed. The fuel consumption of the helicopter with exhaust-heat shield is defined. Integrated assessment of the effectiveness of protection of helicopters from guided missiles with infra-red targeting device can be directly used in practice in test systems for the protection of upgraded and the latest models of helicopters. According to the results of research, mathematical models for determining the fuel consumption of a helicopter with exhaust-heat shields have been developed.

Horizontal heat impacts of a bare facade on air temperature in an adjacent green plot within pedestrian heights in Beijing

2019 ◽  
pp. 1420326X1989267
Author(s):  
Hongxuan Zhou ◽  
Guan Wang ◽  
Dan Hu ◽  
Jing Sun
Keyword(s):  
Heat Flux ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Air Temperature ◽  
Sensible Heat Flux ◽  
Atmospheric Environment ◽  
Dominant Factor ◽  
Sensible Heat ◽  
Significance Level ◽  
The Impact

This study focuses on the horizontal heat impact of facades on the surrounding atmospheric environment at pedestrian heights. The results show that (1) the horizontal heat impact of a facade on the surrounding atmosphere was relatively uniform due to the homogeneous energy flux near the facade; (2) the significance of horizontal heat impacts gradually weakened with height, and the average significance was 48.74% in the spring and 47.81% in the summer; (3) energy factors, such as net radiation, soil heat flux, sensible heat flux, latent heat flux, and ground radiation, influenced the significance of the air temperature difference between the two observation sites where the investigation was conducted; one site was near the facade (distance = 0.30 m), the other one was far from the wall (distance = 10 m), and no dominant factor was found; and (4) the sensible heat flux was higher at the site near the facade than at the site far from the facade at the 0.05 significance level in the summer, which could be attributed to the strong horizontal heat impact from the facade. In contrast, the impact of the facade on the latent heat flux was not significant at the 0.05 significance level in the summer.

scholarly journals The Impact of Climate Warming on Lake Surface Heat Exchange and Ice Phenology of Different Types of Lakes on the Tibetan Plateau

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 634
Author(s):  
Jiahe Lang ◽  
Yaoming Ma ◽  
Zhaoguo Li ◽  
Dongsheng Su
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
Climate Warming ◽  
Significant Feature ◽  
The Tibetan Plateau ◽  
Lake Surface ◽  
Rate Of Increase ◽  
The Impact ◽  
Ice Phenology

Increasing air temperature is a significant feature of climate warming, and is cause for some concern, particularly on the Tibetan Plateau (TP). A lack of observations means that the impact of rising air temperatures on TP lakes has received little attention. Lake surfaces play a unique role in determining local and regional climate. This study analyzed the effect of increasing air temperature on lake surface temperature (LST), latent heat flux (LE), sensible heat flux (H), and ice phenology at Lake Nam Co and Lake Ngoring, which have mean depths of approximately 40 m and 25 m, respectively, and are in the central and eastern TP, respectively. The variables were simulated using an adjusted Fresh-water Lake (FLake) model (FLake_α_ice = 0.15). The simulated results were evaluated against in situ observations of LST, LE and H, and against LST data derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) for 2015 to 2016. The simulations show that when the air temperature increases, LST increases, and the rate of increase is greater in winter than in summer; annual LE increases; H and ice thickness decrease; ice freeze-up date is delayed; and the break-up date advances. The changes in the variables in response to the temperature increases are similar at the two lakes from August to December, but are significantly different from December to July.

scholarly journals Association between Surface Air Temperature And Land Use On The Campus Scale

2020 ◽  
Vol 5 (3) ◽  
pp. 161-169
Author(s):  
Satrio Muhammad Alif ◽  
Erwin Yosua ◽  
Adam Irwansyah Fauzi ◽  
Bambang Edhi Leksono
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Temperature Measurement ◽  
Air Temperature ◽  
Anthropogenic Activities ◽  
Surface Air Temperature ◽  
Least Square ◽  
Rubber Plantation ◽  
Linear Regression Method ◽  
The Impact

The increasing trend of global temperature is related to the land use change in the form of urbanization. The impact of land use change to surface air temperature in Indonesia especially in smaller scope in Indonesia have not researched yet. The study area is located on newly built campus and the development of land use change inside campus can be managed carefully. This research aim is to determine which land use affecting high-temperature by using multiple linear regression method with least square approach so that temperature increase can be controlled in which some land uses must be preserved in urbanization. Land use data is interpreted from the photo map of 275 hectare campus. Temperature data is measured by using the digital thermometer three times a day. The method idea is to obtain distinctive contribution of every land use to every temperature measurement point. The contribution follows the inverse distance weighted concept. Surface air temperature measurement points are located with 150 meter interval and centroids of land use polygons are used for association calculation. Temperature measurement shows values between 25.5oC and 35.4oC. Land use with more anthropogenic activities and rubber plantation are the top contributors to high surface air temperature within a day. In the non-built-up land use category, water body increases the temperature in the daytime. Anthropogenic activities and vegetation density within land use is the main factor in increasing the surface air temperature so that it is suggested to plant farm-like vegetation around every built-up land use.

Ablative Heat Shield Design for Reentry Vehicle Using Numerical Analysis

2014 ◽  
Vol 598 ◽  
pp. 298-303
Author(s):  
Amir Mahdi Tahsini ◽  
Samaneh Tadayon Mousavi
Keyword(s):  
Heat Flux ◽  
Heat Shield ◽  
Interface Temperature ◽  
Final Thickness ◽  
Reentry Vehicle ◽  
Simulated Trajectory ◽  
Flux Profile ◽  
Heat Shields ◽  
Energy Equations ◽  
Shield Design

At this paper, the thermal behavior of ablative materials as heat shields for reentry vehicles is investigated numerically. A one-dimensional finite difference solver is developed to simulate governing mass and energy equations. Four ablative materials; AVCO 5026-HCG, Carbon-Phenolic, Nylon-Phenolic, and Silica-Phenolic; are considered as a heat shield material for a reentry capsule with the diameter 2.8 meter. A heat flux profile from a simulated trajectory of a reentry capsule is used for investigation the performance and essential thickness of these four ablative materials. The only restriction for this simulation is the ultimate temperature of the backup structure which is beneath the ablative heat shield. At all simulations, the final thickness is defined by reaching the interface temperature, the temperature of the border between the ablative heat shield and solid shell, to 80±0.5 degrees Celsius. In addition, the sensitivity analysis is carried out to investigate the effect of properties variations on Carbon-Phenolic’s thickness for this specific heat flux profile.

scholarly journals Response of the Energy Balance on the Margin of the Greenland Ice Sheet to Temperature Changes

1990 ◽  
Vol 36 (123) ◽  
pp. 217-221 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Ole B. Olesen
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Air Temperature ◽  
Sensible Heat Flux ◽  
Ice Sheet ◽  
Temperature Response ◽  
Greenland Ice Sheet ◽  
Energy Balance Model ◽  
Balance Model ◽  
Sensible Heat

AbstractDaily ice ablation on two outlet glaciers from the Greenland ice sheet, Nordbogletscher (1979–83) and Qamanârssûp sermia (1980–86), is related to air temperature by a linear regression equation. Analysis of this ablation-temperature equation with the help of a simple energy-balance model shows that sensible-heat flux has the greatest temperature response and accounts for about one-half of the temperature response of ablation. Net radiation accounts for about one-quarter of the temperature response of ablation, and latent-heat flux and errors account for the remainder. The temperature response of sensible-heat flux at QQamanârssûp sermia is greater than at Nordbogletscher mainly due to higher average wind speeds. The association of high winds with high temperatures during Föhn events further increases sensible-heat flux. The energy-balance model shows that ablation from a snow surface is only about half that from an ice surface at the same air temperature.

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