Erratum: “Time-average temperature distribution in a thermoacoustic stack” [J. Acoust. Soc. Am. 103, 380–388 (1998)]

1999 ◽  
Vol 105 (1) ◽  
pp. 567-567 ◽  
Author(s):  
George Mozurkewich
Keyword(s):  
Temperature Distribution ◽  
Average Temperature ◽  
Time Average

scholarly journals An analytical method to estimate temperature distribution of typical radiant floor cooling systems with internal heat radiation

2021 ◽  
pp. 014459872199800
Author(s):  
Xiaolong Wang ◽  
Wenke Zhang ◽  
Qingqing Li ◽  
Zhenqiang Wei ◽  
Wenjun Lei ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Internal Heat ◽  
Single Layer ◽  
Heat Radiation ◽  
Transfer Model ◽  
Cooling Systems ◽  
Average Temperature ◽  
Floor Surface ◽  
Floor Structure

Radiant floor cooling systems are increasingly used in practice. The temperature distribution on the floor surface and inside the floor structure, especially the minimum and average temperature of floor surface, determines the thermal performance of radiant floor systems. A good temperature distribution of the floor structure is very important to prevent occupant discomfort and avoid possible condensation in summer cooling. In this study, based on the heat transfer model of the single-layer homogeneous floor structure when there is no internal heat radiation in the room, this paper proposes a heat transfer model of single-layer floor radiant cooling systems when the room has internal heat radiation. Using separation variable methods, an analytical solution was developed to estimate temperature distribution of typical radiant floor cooling systems with internal heat radiation, which can be used to calculate the minimum temperature and the average temperature of typical composite floor structure. The analytical solution was validated by experiments. The values of the measured experiments are in a good agreement with the calculations. The absolute error between the calculated and the measured floor surface temperatures was within 0.45°C. The maximum relative error was within 2.31%. Prove that this model can be accepted. The proposed method can be utilized to calculate the cooling capacity of a typical multi-layer composite floor and will be developed in the future study for design of a typical radiant floor cooling system.

Numerical Simulation of Temperature Distribution in a Containment Vessel of an Operating PWR Plant

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
Yoichi Utanohara ◽  
Michio Murase ◽  
Akihiro Masui ◽  
Ryo Inomata ◽  
Yuji Kamiya
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Heat Release ◽  
Gas Phase ◽  
Large Temperature ◽  
Measured Temperature ◽  
Average Temperature ◽  
Containment Vessel ◽  
Large Temperature Gradient

The structural integrity of the containment vessel (CV) for a pressurized water reactor (PWR) plant under a loss-of-coolant accident is evaluated by a safety analysis code that uses the average temperature of gas phase in the CV during reactor operation as an initial condition. Since the estimation of the average temperature by measurement is difficult, this paper addressed the numerical simulation for the temperature distribution in the CV of an operating PWR plant. The simulation considered heat generation of the equipment, the ventilation and air conditioning systems (VAC), heat transfer to the structure, and heat release to the CV exterior based on the design values of the PWR plant. The temperature increased with a rise in height within the CV and the flow field transformed from forced convection to natural convection. Compared with the measured temperature data in the actual PWR plant, predicted temperatures in the lower regions agreed well with the measured values. The temperature differences became larger above the fourth floor, and the temperature inside the steam generator (SG) loop chamber on the fourth floor was most strongly underestimated, −16.2  K due to the large temperature gradient around the heat release equipment. Nevertheless, the predicted temperature distribution represented a qualitative tendency, low at the bottom of the CV and increases with a rise in height within the CV. The total volume-averaged temperature was nearly equal to the average gas phase temperature. To improve the predictive performance, parameter studies regarding heat from the equipment and the reconsideration of the numerical model that can be applicable to large temperature gradient around the equipment are needed.

Infrared Thermal Image on Vapor-Liquid Interface in Capillary Microgrooves Heat Sink

2009 ◽  
Author(s):  
Tao Wang ◽  
Xuegong Hu ◽  
Dawei Tang ◽  
Chaohong Guo
Keyword(s):  
Temperature Distribution ◽  
Heat Sink ◽  
Solid Wall ◽  
Thermal Image ◽  
Liquid Interface ◽  
Liquid Interfaces ◽  
Average Temperature ◽  
Solid Walls ◽  
Working Liquid ◽  
Vapor Liquid

An infrared thermoviewer is utilized to measure the temperature distribution on solid walls and vapor-liquid interfaces of the rectangular capillary microgrooves heat sink, which is made of borosilicate glass. The infrared thermal image clearly shows that the solid wall temperature of microgroove top is lower than the average temperature of vapor-liquid interface. The results indicate that heat source position has a significant influence on the microgrooves surface temperature distribution, besides working liquid, tilt angle (the angle between microgroove surface and gravity direction) and heat flux.

The Influence of Hydrodynamic Bearing Configuration on Morton Effect

2016 ◽  
Author(s):  
Xiaomeng Tong ◽  
Alan Palazzolo
Keyword(s):  
Temperature Distribution ◽  
Film Thickness ◽  
Temperature Difference ◽  
Thermal Excitation ◽  
Vibration Level ◽  
Critical Speeds ◽  
Average Temperature ◽  
Bearing Clearance ◽  
Comparison Results ◽  
Morton Effect

The Morton effect (ME) results from the synchronous, thermal excitation of a rotating shaft because of the uneven viscous shearing in hydrodynamic bearings and the asymmetric temperature distribution in shafts. The temperature difference bends the rotor, reducing the film thickness and increasing the thermal unbalance, which may cause excessive vibration level and unsteady phase angle. To predict the potential thermal instability from the ME, the finite element method is used to solve the transient rotordynamics and temperature distribution in the lubricant, bearing and shaft. The conventional thermal unbalance method is replaced by a more accurate thermal shaft bow model for rotordynamic analysis and the three-dimensional energy equation is utilized for the lubricant temperature prediction. Considering that the temperature change in the shaft and bearing occurs quite slowly relative to the shaft vibration deflection change, a staggered scheme is employed to assign a longer period to update the system temperature distribution and a shorter period to update the vibration orbits. Verified by a real overhung compressor model, the ME instability onset speed predicted by simulation coincides with the tested speed, at which large vibration level is observed. The hysteresis phenomenon, which is quite typical for thermal-induced vibration problems, can be caused by the ME and is demonstrated by the simulation. A stability recovery speed is confirmed, above which the vibration level and the rotor temperature difference will decrease to an acceptable level and the system will become stable. To investigate the influence of bearing configuration on ME, different bearing types including fixed pad bearings (FPBs) and tilting pad bearings (TPBs) with various pad numbers are analyzed. Meanwhile, the bearing clearance and preload intentionally remain unchanged in the comparison. Results show that despite similar critical speeds, the TPBs are better at suppressing the ME with lower average temperature and larger film thickness in the lubricant, especially at high speeds. This is due to the self-tilting ability for the TPBs to maintain a satisfactory bearing clearance. The four-pad TPBs outperform the five-pad TPBs with both lower average temperature and smaller temperature difference in the shaft considering that the effective load-carrying area is larger in the 4-pad bearings. Moreover, the asymmetric pivot offset of 0.6 is simulated to demonstrate its superiority in mitigating the ME compared with the common 0.5 offset. Considering that the ME instability occurs in the vicinity of the critical speeds in most cases, the bearing diameter-length ratio should be carefully designed to achieve a larger separation margin.

Nonlinear Thermal Flutter Analysis of Supersonic Composite Laminated Panels Using Differential Quadrature Method

2014 ◽  
Vol 14 (07) ◽  
pp. 1450030 ◽  
Author(s):  
Yaobin Niu ◽  
Zhongwei Wang ◽  
Weihua Zhang
Keyword(s):  
Temperature Distribution ◽  
Differential Quadrature Method ◽  
Differential Quadrature ◽  
Composite Panel ◽  
Frequency Interval ◽  
Composite Panels ◽  
Quadrature Method ◽  
Average Temperature ◽  
Aspect Ratios ◽  
Temperature Load

In this paper, the differential quadrature method (DQM) was extended to deal with the nonlinear thermal flutter problem of supersonic composite laminated panel. Based on Hamilton's principle, the nonlinear thermal flutter model of composite panels was first established. The model adopted the von Karman large deflection plate theory for the geometrical nonlinearity, and the third order piston theory for the supersonic aerodynamic loads. Convergence and accuracy studies were carried out to verify the proposed approach. Finally, the nonlinear thermal flutter characteristics of a supersonic composite panel were studied. Uniform temperatures were first applied to the model in order to determine general heating effects on the stability of the composite panel. Owing to the varying structural stiffness of composite panels when subjected to thermal stresses, the thermal load reduced the frequency of composite panel, as well as the frequency interval between the first frequency and the second frequency; thereby hastening the flutter of composite panel. The nonlinear thermal flutter velocity ratio was decreased with respect to increasing temperature load for all aspect ratios. However, the influence of thermal loadings on flutter with various cross angles was different. Cases of unequal temperatures were considered. The average temperature load was kept constant which differs from the temperature gradient form of loading. The results show that the nonlinear thermal frequencies are affected in the presence of different temperature distributions. The changes in the temperature distribution have a slightly greater effect than changes in the average temperature. These effects due to temperature distribution changes do not have a substantial effect on the flutter dynamic pressure.

Preliminary CFD Investigation of Syngas Combustion at Different Operating Pressures

2015 ◽  
Vol 786 ◽  
pp. 215-219
Author(s):  
Norhaslina Mat Zian ◽  
Hasril Hasini ◽  
Nur Irmawati Om
Keyword(s):  
Temperature Distribution ◽  
Thermal Power ◽  
Combustion Process ◽  
Pressure Variation ◽  
Operating Pressure ◽  
Gas Turbine Combustor ◽  
Average Temperature ◽  
Conventional Combustion ◽  
Synthetic Gas ◽  
Syngas Combustion

Study on the flow and combustion behavior inside gas turbine combustor used in thermal power plant is described in this paper. The combustion process takes place using synthetic gas and emphasis is given to the effect of pressure variation on flame profile, temperature distribution and emissions as compared to the conventional combustion using methane. The operating pressure of the can-type combustor varies in the range of 1-10 atm. while the syngas composition is assumed to have fixed values of 10% CH4, 55% CO, 30% H2 and 5% N2. Preliminary result shows that the flow inside the can-combustor is highly swirling which indicates good mixing of fuel and air prior to the entrance of the mixture to the main combustion zone. The temperature distribution at combustor mid plane show identical pattern for pressure range between 1-10 atm for both maximum and average temperature magnitude.

Thermal Behavior of Multidisk Friction Pairs in Hydroviscous Drive Considering Inertia Item

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Fangwei Xie ◽  
Jianzhong Cui ◽  
Gang Sheng ◽  
Cuntang Wang ◽  
Xianjun Zhang
Keyword(s):  
Surface Roughness ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Outer Radius ◽  
Transient Temperature ◽  
Unsteady Temperature ◽  
Temperature Correlation ◽  
Average Temperature ◽  
Soft Start ◽  
Lubricant Viscosity

Considering the influence of the inertia item on temperature distribution of multidisk friction pairs in hydroviscous drive (HVD), transient temperature models are derived with the aim of revealing the effect of engagement pressure, lubricant viscosity, viscosity–temperature correlation, surface roughness and the ratio of inner and outer radius of disks on temperature distribution. The results indicate that unsteady temperature gradient can be avoided by matching the suitable materials for multidisk friction pairs. The average temperature for the case of neglecting the inertia item is lower than that of the case of including the inertia item. It is shown that during the soft-start, the temperature along the radial direction achieves its peak value near the outlet and keeps decreasing along the axial direction; while after the engaging process, the temperature distribution tends to be uniform. It is also shown that the decrease of engagement pressure, surface roughness and the ratio of inner and outer radius of disks can reduce temperature gradient effectively as well as the increase of lubricant viscosity. The average temperature for the case of including the viscosity–temperature correlation is much higher than that for other cases.

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