Multidisciplinary Sensitivity Analysis of the Cooling System of a High-Pressure Turbine Blade in the Pre-Design Phase

2021 ◽  
Author(s):  
Barbara Fiedler ◽  
Yannick Muller ◽  
Matthias Voigt ◽  
Ronald Mailach
Keyword(s):  
Mass Flow ◽  
Cooling System ◽  
Mechanical Analysis ◽  
Thermal Design ◽  
Probabilistic Methods ◽  
Cycle Performance ◽  
Design Parameters ◽  
Cooling Systems ◽  
Cooling Air Flow ◽  
Cooling Air

Abstract The engine-cycle performance of jet engines can be improved by more efficient cooling systems, either by reducing the required cooling air or by intensifying the cooling efficiency with the same amount of cooling mass flow. However, the multitude of geometrical design parameters and the strong multidisciplinary aspect of cooling mass flow consumption optimization make designing the cooling systems extremely challenging. Integrating probabilistic methods into the thermal design process enables the automated evaluation of multiple design variants which contributes to the development of more efficient systems. In the present study, the sensitivity of a multi-pass cooling system to geometric variations is investigated. The cooling air flow, solved using a 1D, correlation based flow solver, is iteratively coupled with the 3D-FE thermo-mechanical analysis of the blade. The geometry of the cooling system is varied using the Harmonic-Spline-Deformation parametric, which has been extended to modify the wall thickness enabling to perform a geometrical-holistic analysis. Furthermore, the Elementary-Effects-Method (EEM) and the Monte-Carlo-Simulation (MCS) are compared to identify the most influential parameters and analyze their complex interactions. It is shown that the cooling system’s performance is mostly affected by the shape and position of the first web. Furthermore, MCS proves to be robust towards changes in design space while simultaneously enabling a more detailed analysis of the system behavior compared to EEM.

Perimeter Cooling Unit and Localized Row-Based Cooling Unit Transient Air Flow Effects Modeling and Characterization in Data Centers

2015 ◽  
Author(s):  
Tianyi Gao ◽  
James Geer ◽  
Bahgat G. Sammakia ◽  
Russell Tipton ◽  
Mark Seymour
Keyword(s):  
Thermal Management ◽  
Data Center ◽  
Data Centers ◽  
Cooling System ◽  
Air Flow ◽  
Cooling Systems ◽  
Dynamic Thermal Management ◽  
Hybrid Cooling ◽  
Cooling Unit ◽  
Cooling Air

Cooling power constitutes a large portion of the total electrical power consumption in data centers. Approximately 25%∼40% of the electricity used within a production data center is consumed by the cooling system. Improving the cooling energy efficiency has attracted a great deal of research attention. Many strategies have been proposed for cutting the data center energy costs. One of the effective strategies for increasing the cooling efficiency is using dynamic thermal management. Another effective strategy is placing cooling devices (heat exchangers) closer to the source of heat. This is the basic design principle of many hybrid cooling systems and liquid cooling systems for data centers. Dynamic thermal management of data centers is a huge challenge, due to the fact that data centers are operated under complex dynamic conditions, even during normal operating conditions. In addition, hybrid cooling systems for data centers introduce additional localized cooling devices, such as in row cooling units and overhead coolers, which significantly increase the complexity of dynamic thermal management. Therefore, it is of paramount importance to characterize the dynamic responses of data centers under variations from different cooling units, such as cooling air flow rate variations. In this study, a detailed computational analysis of an in row cooler based hybrid cooled data center is conducted using a commercially available computational fluid dynamics (CFD) code. A representative CFD model for a raised floor data center with cold aisle-hot aisle arrangement fashion is developed. The hybrid cooling system is designed using perimeter CRAH units and localized in row cooling units. The CRAH unit supplies centralized cooling air to the under floor plenum, and the cooling air enters the cold aisle through perforated tiles. The in row cooling unit is located on the raised floor between the server racks. It supplies the cooling air directly to the cold aisle, and intakes hot air from the back of the racks (hot aisle). Therefore, two different cooling air sources are supplied to the cold aisle, but the ways they are delivered to the cold aisle are different. Several modeling cases are designed to study the transient effects of variations in the flow rates of the two cooling air sources. The server power and the cooling air flow variation combination scenarios are also modeled and studied. The detailed impacts of each modeling case on the rack inlet air temperature and cold aisle air flow distribution are studied. The results presented in this work provide an understanding of the effects of air flow variations on the thermal performance of data centers. The results and corresponding analysis is used for improving the running efficiency of this type of raised floor hybrid data centers using CRAH and IRC units.

Hybrid Cooling for Thermal-Electric Power Generation

2013 ◽  
Author(s):  
John S. Maulbetsch
Keyword(s):  
Cooling System ◽  
Meteorological Data ◽  
Combined Cycle ◽  
Plant Performance ◽  
Design Parameters ◽  
Water Requirements ◽  
Cooling Systems ◽  
Capital Costs ◽  
Hybrid Cooling ◽  
Dry Cooling

Water use by power plant cooling systems has become a critical siting issue for new plants and the object of increasing pressure for modification or retrofit at existing plants. Wet cooling typically costs less and results in more efficient plant performance. Dry cooling, while costing more and imposing heat rate and capacity penalties on the plant, conserves significant amounts of water and eliminates any concerns regarding thermal discharge to or intake losses on local water bodies. Hybrid cooling systems have the potential of combining the advantages of both systems by reducing, although not eliminating, water requirements while incurring performance penalties that are less than those from all-dry systems. The costs, while greater than those for wet cooling, can be less than those for dry. This paper addresses parallel wet/dry systems combining direct dry cooling using a forced-draft air-cooled condenser (ACC) with closed-cycle wet cooling using a surface (shell-and-tube) steam condenser and a mechanical-draft, counterflow wet cooling tower as applied to coal-fired steam plants, gas-fired combined-cycle plants and nuclear plants. A brief summary of criteria used to identify situations where hybrid systems should be considered is given. A methodology for specifying and selecting a hybrid system is described along with the information and data requirements for sizing and estimating the capital costs and water requirements a specified plant at a specified site. The methodology incorporates critical plant and operating parameters into the analysis, such as plant monthly load profile, plant equipment design parameters for equipment related to the cooling system, e.g. steam turbine, condenser, wet or dry cooling system, wastewater treatment system. Site characteristics include a water budget or constraints, e.g. acre feet of water available for cooling on an annual basis as well as any monthly or seasonal “draw rate” constraints and meteorological data. The effect of economic parameters including cost of capital, power, water and chemicals for wastewater treating are reviewed. Finally some examples of selected systems at sites of varying meteorological characteristics are presented.

Cooling Air Temperature and Mass Flow Rate Control for Hybrid Electric Vehicle Battery Thermal Management

2014 ◽  
Author(s):  
Xinran (William) Tao ◽  
John Wagner
Keyword(s):  
Mass Flow Rate ◽  
Thermal Management ◽  
Air Temperature ◽  
Mass Flow ◽  
Flow Rate ◽  
Cooling System ◽  
Battery Thermal Management ◽  
Thermal Management System ◽  
Battery Thermal Management System ◽  
Cooling Air

Lithium-Ion (Li-ion) batteries are widely used in electric and hybrid electric vehicles for energy storage. However, a Li-ion battery’s lifespan and performance is reduced if it’s overheated during operation. To maintain the battery’s temperature below established thresholds, the heat generated during charge/discharge must be removed and this requires an effective cooling system. This paper introduces a battery thermal management system (BTMS) based on a dynamic thermal-electric model of a cylindrical battery. The heat generation rate estimated by this model helps to actively control the air mass flow rate. A nonlinear back-stepping controller and a linear optimal controller are developed to identify the ideal cooling air temperature which stabilizes the battery core temperature. The simulation of two different operating scenarios and three control strategies has been conducted. Simulation results indicate that the proposed controllers can stabilize the battery core temperature with peak tracking errors smaller than 2.4°C by regulating the cooling air temperature and mass flow rate. Overall the controllers developed for the battery thermal management system show improvements in both temperature tracking and cooling system power conservation, in comparison to the classical controller. The next step in this study is to integrate these elements into a holistic cooling configuration with AC system compressor control to minimize the cooling power consumption.

Two Papers on Engine Cooling First Paper: The Cooling of Diesel Engines by Water under Pressure

1966 ◽  
Vol 181 (1) ◽  
pp. 105-114
Author(s):  
J. Gratzmuller ◽  
S. J. Davies
Keyword(s):  
Diesel Engines ◽  
Cooling System ◽  
Lubricating Oil ◽  
Standard Equipment ◽  
Cooling Systems ◽  
Engine Cooling ◽  
Heating And Cooling ◽  
In Series ◽  
High Static Pressure ◽  
Cooling Air

Water cooling in diesel engines is studied, with particular reference to the application of these engines in locomotives of high power. In this context, problems relating to weight, volume and radiator design become progressively more difficult to solve with the tendency towards increased unit powers. In the solution considered the water in the cooling system is put under a high static pressure, which makes it possible to raise the water temperatures above the usual levels. Resulting from this, the formation of steam bubbles is reduced or eliminated, ‘cavitation corrosion’ is reduced considerably, and cavitation in the water pump is prevented. Water consumption is markedly reduced. Standard equipment for locomotives is described. Cooling the supercharge air and the lubricating oil at relatively low temperatures is compatible with cooling the engine at a high temperature if two cooling circuits are used, with their radiators placed in series in the cooling air current. The case of cooling engines of high supercharge is examined; in these, the heat taken from the admission air and from the lubricating oil exceeds that taken from the engine. Future designs of heating and cooling systems for engines with very high supercharge are proposed.

Experimental Study on Pressure Losses in Circular Orifices for the Application in Internal Cooling Systems

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Christian Binder ◽  
Mats Kinell ◽  
Esa Utriainen ◽  
Daniel Eriksson ◽  
Mehdi Bahador ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Discharge Coefficient ◽  
Air Flow ◽  
Internal Cooling ◽  
Cooling Systems ◽  
Pressure Losses ◽  
Flow Through ◽  
Cooling Air Flow ◽  
New Phenomena ◽  
Cooling Air

The cooling air flow in a gas turbine is governed by the flow through its internal passages and controlled by restrictors such as circular orifices. If the cooling air flow is incorrectly controlled, the durability and mechanical integrity of the whole turbine may be affected. Consequently, a good understanding of the orifices in the internal passages is important. This study presents experimental results for a range of pressure ratios and length-to-diameter ratios common in gas turbines including even very small pressure ratios. Additionally, the chamfer depth at the inlet was also varied. The results of the chamfer depth variation confirmed its beneficial influence on decreasing pressure losses. Moreover, important effects were noted when varying more than one parameter at a time. Besides earlier mentioned hysteresis at the threshold of choking, new phenomena were observed, e.g., a rise of the discharge coefficient for certain pressure and length-to-diameter ratios. A correlation for the discharge coefficient was attained based on the new experimental data with a generally lower error than previous studies.

Thermal Environment Tests of a High-Speed Aircraft Cockpit

1964 ◽  
Vol 15 (3) ◽  
pp. 203-218 ◽  
Author(s):  
T. L. Hughes
Keyword(s):  
High Speed ◽  
Thermal Environment ◽  
Cooling System ◽  
Air Flow ◽  
Internal Heat ◽  
Inlet Temperature ◽  
A Value ◽  
Heat Leakage ◽  
Cooling Air Flow ◽  
Cooling Air

SummaryThis paper describes rig tests made to evaluate the effectiveness of the cockpit insulation and cooling system of a high-speed aircraft.The tests showed the dependence of cockpit internal temperature distribution and heat pick-up on the cooling air mass flow and inlet temperature. Analysis of the test data showed that there was considerable heat leakage into the cockpit; the heat leakage increased with cooling air flow and constituted two-thirds of the heat entering the cockpit when the air flow was moderately high (20 lb/min). Some of the leakage heat entered the cockpit through equipment mountings but it was evident that other leakage paths existed. One more obvious heat leakage path, at the canopy, is illustrated.The tests also showed that the internal heat transfer coefficient increased with air flow, reaching a value of 2·5 C.H.U./hr ft2°C when the flow was 20 lb/min.

scholarly journals ANALISIS DESAIN PROSES SISTEM PENDINGIN PADA REAKTOR RISET INOVATIF 50 MW

2015 ◽  
Vol 17 (1) ◽  
pp. 19 ◽  
Author(s):  
Sukmanto Dibyo ◽  
Endiah Puji Hastuti ◽  
Ign. Djoko Irianto
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cooling System ◽  
Reactor Core ◽  
Material Testing ◽  
Thermal Design ◽  
Coolant Pump ◽  
Energy Balances ◽  
Coolant System

Reaktor Riset Inovatif (RRI) merupakan jenis MTR (Material Testing Reactor) yang dipersiapkan ke depan sebagai desain reaktor baru. Daya RRI telah ditetapkan dari perhitungan neutronik dan termohidrolika teras yaitu 50 MW termal. Reaktor bertekanan 8 kgf/cm2 dan laju aliran massa pendingin primer 900 kg/s. Tantangan yang penting dalam menindak lanjuti desain reaktor ini adalah analisis desain pada sistem pendingin. Makalah ini bertujuan untuk menganalisis desain proses sistem pendingin utama reaktor RRI daya 50 MW (RRI-50) dengan menggunakan program Chemcad 6.1.4. Dalam analisis ini dilakukan perhitungan neraca massa dan energi (mass/energy balances) pada sistem pendingin primer dan sekunder sebagai pendingin utama. Masing-masing sistem pendingin tersebut terdiri dari 2 jalur beroperasi secara paralel dan 1 jalur redundansi. Disamping itu untuk desain termal unit komponen telah dianalisis dengan program RELAP5, frenchcreek dan Metoda Analitik. Hasil analisis yang diperoleh adalah desain diagram sistem pendingin yang mencakup data parameter entalpi, temperatur, tekanan dan laju aliran massa pendingin untuk masing-masing jalur. Adapun hasil desain unit komponen utama pada RRI-50 adalah tangki tunda dengan volume 51,5 m3, 2 unit pompa sentrifugal dan 1 unit pompa cadangan pada pendingin primer daya 141 kW/pompa dan pendingin sekunder daya 206 kW/pompa, 2 unit penukar panas tipe shell-tube dengan koefisien termal overall 1377 W/m2.oC dan 4 unit menara pendingin yang mampu melepaskan panas ke udara dengan desain temperatur approach 5,0 oC dan temperatur range 9,0 oC. Desain sistem pendingin reaktor RRI-50 ini telah menetapkan parameter operasi sistem pendingin yaitu temperatur, tekanan dan laju aliran massa pendingin dengan mempertimbangkan tuntutan aspek keselamatan teras reaktor sehingga desain temperatur maksimum pendingin masuk ke teras 44,5 oC. Kata kunci : RRI 50 MW, desain sistem pendingin, program Chemcad 6.1.4   Innovative Research Reactor RRI is a type of MTR (Material Testing Reactor), which is being prepared in the future as a design of new reactor. The power of RRI has been determined based on the core thermalhydraulic and neutronic calculation, which is 50 MWt. The reactor pressure is 8 kgf/cm 2 and coolant mass flow rate is 900 kg/s. The important challenge in the follow up of this reactor design is the design analysis of cooling system. The purpose of this study is to analyze the design of RRI reactor main coolant system at the power of 50 MWt (RRI-50) using ChemCAD 6.1.4. In this analysis the mass and energy balances at the primary and secondary cooling system are calculated as main coolant. Each of the cooling system consists of two lines operating in parallel and redundancy lines. Besides that, the thermal design of the component units have been analyzed using RELAP5, FrenchCreek and Analytical Methods. The analyses result obtained is a design of cooling system diagram which includes parameter of enthalpy, temperature, pressure and coolant mass flow rate of each line. Meanwhile, design result of main component unit are delay tank of 51.5 m3 volume, 2 unit centrifugal pumps and 1 unit stand-by pump for the primary coolant pump each of 141 kW power and secondary coolant pump each of 206 kW power, 2 unit of shell-tube heat exchanger with overall thermal coefficient of 1377 W/m2.oC and 4 unit cooling tower that capable to release the heat to the air at approach temperature of 5,0 oC and range temperature of 9,0 oC. design of reactor coolant system RRI-50 has decided the operating parameters of cooling system are temperature, pressure and mass flow rate by considering into the demands of the safety aspects of the reactor core therefore design of maximum coolant temperature to the reactor core is 44,5 oC. Keywords : RRI 50MW,  design of cooling system, program Chemcad 6.1.4.

Parameter Study on Cooling System of Battery for HEV

2012 ◽  
Vol 538-541 ◽  
pp. 2038-2042
Author(s):  
Zhen Zhe Li ◽  
Yun De Shen ◽  
Gui Ying Shen ◽  
Mei Qin Li ◽  
Ming Ren
Keyword(s):  
Heat Flux ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cooling System ◽  
Parameter Study ◽  
Analysis Model ◽  
Rate Of Cooling ◽  
Future Work ◽  
Cooling Air

A hybrid power composed of the fuel cell and MH-Ni battery has become a good strategy for HEV, but the performance of the battery cooling systems can not be easily adjusted. In this study, heat flux of the batteries and mass flow rate of cooling air have been investigated to improve the performance of a battery cooling system. As shown in the results, the error of root mean square has been decreased under the condition of decreasing heat flux of the batteries, and the performance of the battery cooling system has been improved with increasing the mass flow rate of cooling air. The analysis model developed in this study can be widly used to find out an optimal battery cooling system in the future work.

Numerical and Experimental Characterization of the Transient Effectiveness of a Water to Air Heat Exchanger for Data Center Cooling Systems

2015 ◽  
Author(s):  
Tianyi Gao ◽  
Marcelo del Valle ◽  
Alfonso Ortega ◽  
Bahgat G. Sammakia
Keyword(s):  
Heat Exchanger ◽  
Mass Flow ◽  
Data Center ◽  
Heat Exchangers ◽  
Cooling System ◽  
Cross Flow ◽  
Inlet Temperature ◽  
Experimental Measurements ◽  
Cooling Systems ◽  
Flow Heat

The cross flow heat exchanger is at the heart of most cooling systems for data centers. Air/Water or air/refrigerant heat exchangers are the principal component in Central Room Air Conditioning (CRAC) units that condition data room air that is delivered through an underfloor plenum. Liquid/air heat exchangers are also increasingly deployed in close-coupled cooling systems such as rear door heat exchangers, in-row coolers, and overhead coolers. In all cases, the performance of liquid/air heat exchangers in both steady state and transient scenarios are of principal concern. Transient scenarios occur either by the accidental failure of the cooling system or by intentional dynamic control of the cooling system. In either scenario, transient boundary conditions involve time-dependent air or liquid inlet temperatures and mass flow rates that may be coupled in any number of potential combinations. Understanding and characterizing the performance of the heat exchanger in these transient scenarios is of paramount importance for designing better thermal solutions and improving the operational efficiency of existing cooling systems. In this paper, the transient performance of water to air cross flow heat exchangers is studied using numerical modeling and experimental measurements. Experimental measurements in 12 in. × 12 in. heat exchanger cores were performed, in which the liquid (water) mass flow rate or inlet temperature are varied in time following controlled functional forms (step jump, ramp). The experimental data were used to validate a transient numerical model developed with traditional assumptions of space averaging of heat transfer coefficients, and volume averaging of thermal capacitances. The complete numerical model was combined with the transient effectiveness methodology in which the traditional heat exchanger effectiveness approach is extended into a transient domain, and is then used to model the heat exchanger transient response. Different transient scenarios were parametrically studied to develop an understanding of the impact of critical variables such as, the fluid inlet temperature variation and the fluid mass flow rate variation, and a more comprehensive understanding of the characteristics of the transient effectiveness. Agreement between the novel transient effectiveness modeling approach and the experimental measurements enable use of the models as verified predictive design tools. Several studies are designed based on the practical problems related to data center thermal environments and the results are analyzed.

The Fluid Dynamics of a Shrouded Disk System With a Radial Outflow of Coolant

1970 ◽  
Vol 92 (3) ◽  
pp. 335-341 ◽  
Author(s):  
F. J. Bayley ◽  
J. M. Owen
Keyword(s):  
Pressure Distribution ◽  
Mass Flow ◽  
Turbine Disk ◽  
Disk System ◽  
Reynolds Analogy ◽  
Distribution Moment ◽  
Cooling Air Flow ◽  
The Moment ◽  
Radial Outflow ◽  
Cooling Air

This paper describes an experimental study of an air-cooled gas turbine disk using the model of a disk rotating near a shrouded stator. Measurements of pressure distribution, frictional moment, and the cooling air flow necessary to prevent the ingress of hot gases over the turbine disk are described for a range of rotational speeds, mass flow rates, and different geometries. The pressure distribution is shown to be calculable by the superposition of the pressure drop due to the shroud and the unshrouded distribution. Moment coefficients are shown to increase with increasing mass flow rate and decreasing shroud clearance, but are little affected by the rotor/stator gap. Applying Reynolds analogy to the moment coefficients, it is estimated that heat transfer from the rotor will be controlled primarily by rate of radial cooling flow at low rotational Reynolds numbers, and will be governed primarily by Reynolds number at large rotational speeds.

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