Theoretical and Numerical Analysis on the Temperature Drop and Power Consumption of a Pre-Swirl System

2016 ◽  
Author(s):  
Gaowen Liu ◽  
Heng Wu ◽  
Qing Feng ◽  
Songling Liu
Keyword(s):  
Theoretical Analysis ◽  
Power Consumption ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Temperature Drop ◽  
Cover Plate ◽  
Radial Location ◽  
Total Temperature ◽  
Cooling Air

As a component of delivering cooling air to turbine rotor blade at appropriate pressure, temperature and mass flow rate, pre-swirl system is very important to the cooling of turbine blades. It is attractive to the designers and scholars for its potential ability to reduce relative total temperature of cooling air as large as 100K. A pre-swirl system is actually an aero-thermodynamic system with energy transformation between work and heat. Theoretical analysis was carried out on an isentropic pre-swirl system to deduce equations for ideal temperature drop and power consumption. For an actual pre-swirl system, correlation between the actual temperature drop and power consumption was deduced, and a temperature drop effectiveness was defined also. Theoretical analysis shows that the system’s temperature drop increases linearly with the reduction of the power consumption. Numerical models were derived from a real engine pre-swirl system with small simplification. Standard k-ε turbulence model and Frozen-Rotor approach were applied in the three dimensional steady simulations. Inlet total pressure and total temperature, outlet static pressure, mass flow rate delivered to the blade and rotating speed of rotor were kept to be fixed for all the models. The influences of heat transfer and sealing flow coming from the inner seal were ignored in the simulations. Section averaged parameters like pressure, swirl ratio and total enthalpy were presented at each typical station throughout the flow path. The relationship between the temperature drop and the power consumption of all the models has been verified to be consistent with the deduced formula. For the pre-swirl system with low radial location of nozzle, these measures, such as adding impellers in the cover-plate cavity and inclining the receiver hole, were taken to reduce the power consumption and enlarge the temperature drop obviously. For this specific pre-swirl system, models with high radial location of nozzle are more recommended to decrease the loss caused by the large circumferential velocity difference between the airflow and the rotor.

Effect of pre-swirl nozzle closure modes on unsteady flow and heat transfer characteristics in a pre-swirl system of aero-engine

2021 ◽  
pp. 095441002110191
Author(s):  
Gaowen Liu ◽  
Zhao Lei ◽  
Aqiang Lin ◽  
Qing Feng ◽  
Yan Chen
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Temperature Drop ◽  
Thermodynamic Characteristics ◽  
Circumferential Direction ◽  
Temperature Changes ◽  
Air Supply ◽  
Cooling Air

The pre-swirl system is of great importance for temperature drop and cooling air supply. This study aims to investigate the influencing mechanism of heat transfer, nonuniform thermodynamic characteristics, and cooling air supply sensitivity in a pre-swirl system by the application of the flow control method of the pre-swirl nozzle. A novel test rig was proposed to actively control the supplied cooling air mass flow rate by three adjustable pre-swirl nozzles. Then, the transient problem of the pre-swirl system was numerically conducted by comparison with 60°, 120°, and 180° rotating disk cavity cases, which were verified with the experiment results. Results show that the partial nozzle closure will aggravate the fluctuation of air supply mass flow rate and temperature. When three parts of nozzles are closed evenly at 120° in the circumferential direction, the maximum value of the nonuniformity coefficient of air supply mass flow rate changes to 3.1% and that of temperature changes to 0.25%. When six parts of nozzles are closed evenly at 60° in the circumferential direction, the maximum nonuniformity coefficient of air supply mass flow rate changes to 1.4% and that of temperature changes to 0.20%. However, different partial nozzle closure modes have little effect on the average air supply parameters. Closing 14.3% of the nozzle area will reduce the air supply mass flow rate by 9.9% and the average air supply temperature by about 1 K.

Effect of Active Modulation of Through-Casing Coolant Injection on Turbine Efficiency

2017 ◽  
Author(s):  
Brian M. T. Tang ◽  
Marko Bacic ◽  
Peter T. Ireland
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Total Pressure ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Turbine Efficiency ◽  
Coolant Injection ◽  
Cooling Air

This paper presents a computational investigation into the impact of cooling air injected through the stationary over-tip turbine casing on overall turbine efficiency. The high work axial flow turbine is representative of the high pressure turbine of a civil aviation turbofan engine. The effect of active modulation of the cooling air is assessed, as well as that of the injection locations. The influence of the through-casing coolant injection on the turbine blade over-tip leakage flow and the associated secondary flow features are examined. Transient (unsteady) sliding mesh simulations of a one turbine stage rotor-stator domain are performed using periodic boundary conditions. Cooling air configurations with a constant total pressure air supply, constant mass flow rate and actively controlled total pressure supply are assessed for a single geometric arrangement of cooling holes. The effects of both the mass flow rate of cooling air and the location of its injection relative to the turbine rotor blade are examined. The results show that all of the assessed cooling configurations provided a benefit to turbine row efficiency of between 0.2 and 0.4 percentage points. The passive and constant mass flow rate configurations reduced the over-tip leakage flow, but did so in an inefficient manner, with decreasing efficiency observed with increasing injection mass flow rate beyond 0.6% of the mainstream flow, despite the over-tip leakage mass flow rate continuing to reduce. By contrast, the active total pressure controlled injection provided a more efficient manner of controlling this leakage flow, as it permitted a redistribution of cooling air, allowing it to be applied in the regions close to the suction side of the blade tip which more directly reduced over-tip leakage flow rates and hence improved efficiency. Cooling air injected close to the pressure side of the rotor blade was less effective at controlling the leakage flow, and was associated with increased aerodynamic loss in the passage vortex.

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.

Redesigning the Auxiliary Power Unit Bleed Air Venturi

2012 ◽  
Author(s):  
Adam Dick ◽  
Peter Diamond
Keyword(s):  
Gas Turbine ◽  
Mass Flow Rate ◽  
Power Unit ◽  
Mass Flow ◽  
Flow Rate ◽  
Cold Weather ◽  
Auxiliary Power Unit ◽  
Auxiliary Power ◽  
Main Engine ◽  
Cooling Air

This paper examines the analysis of re-designing the Auxiliary Power Unit (APU) bleed air spool piece used on the Landing Craft, Air Cushion (LCAC). The APU supplies bleed air for main engine (ME) starting, anti-icing of the propeller shrouds during cold weather conditions and anti-icing of the filtration system that supplies both ME compartment cooling air and the APU gas turbine combustion air. An air-blast cockpit windshield cleaning system is also powered by APU bleed air. A spool piece is a venturi whose function is to limit a specific amount of airflow as it passes through a system. The current spool piece venturi dimensions allow an excess in APU bleed air to on-craft components, resulting in an exhaust gas temperature (EGT) over-temp in the gas turbine power producer. Such operating conditions occur during cold weather testing, when port and starboard propeller shroud anti-ice systems and APU combustion air/main engine compartment cooling air anti-ice systems are operating. In order to rectify this issue, a model analysis was created, determining the proper dimension of the spool piece venturi. Because spool piece venturies have been implemented fleet wide, it was a priority to reduce fabrication expenses of new materials. To best achieve this, the analysis will determine the size of a plain venturi that can be installed within the existing spool pieces. Referring to engine specifications, APU bleed air was limited to a certain flow rate. However, anti-ice components also required a specific mass flow rate in order to operate properly. It is within these boundaries that the proper diameter of the venturi was determined. This issue further expands upon the analysis of thermal testing, inlet and outlet pressures and the mass flow rate of the new venturi dimension.

Prediction of Performance Equations for Household Compressors Depending on Manufacturing Data for Refrigerators and Freezers

2016 ◽  
Vol 818 ◽  
pp. 184-209
Author(s):  
Louay Abdalazez Mahdi ◽  
Emad Esmaael Habib ◽  
Laith Abdalmunam
Keyword(s):  
Power Consumption ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cooling Capacity ◽  
Surface Fitting ◽  
Temperature Cycle ◽  
Evaporator Temperature ◽  
Base Points ◽  
Swept Volume

A semi-empirical model has been investigated to represent household compressors. The model based on calorimeter data for two distinguished brand (Danfoss and Electrolux CUBIGEL) and compared with eight brands consisting of ninety compressors model. The calorimeter data are correlated (according to ARI standard 540-90 [1] and working refrigeration temperature cycle for ASHRAE Technical Committee 8.9[2]) as a function of refrigerant saturated evaporating temperatures from (-35 to 10) °C and swept volume range (2.24-11.15) cm3 keeping of the refrigerant saturated condensing temperature constant at 54.5 °C. The correlations were found with ten-coefficient polynomial by using Matlab software – surface fitting method for cooling capacity, power consumption, and refrigerant mass flow rate.In addition, other equations for cooling capacity, power consumption, and refrigerant mass flow rate at-23.3 °C evaporator temperature, 54.4 °C condenser temperature, and 32 °C temperature for liquid line which is the base points of the refrigerator cycle according to ASHRAE[2] , cover the range (2.42-11.15) cm3 swept volume which are created to quick choose the proper compressor.The result indicated that the surface fitting models are accurate within ± 15% deviation of compressors data of seventy-two models for cooling capacity, fifty models for power, and twenty-five models for refrigerant mass flow rate.

Numerical Investigation on the Flow Characteristics in a Cover-Plate Pre-Swirl System

2021 ◽  
Author(s):  
Menghua Jian ◽  
Xuesen Yang ◽  
Wei Dong
Keyword(s):  
Reynolds Number ◽  
Numerical Investigation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Circumferential Velocity ◽  
Cover Plate ◽  
Temperature Reduction

Abstract This paper presents a numerical investigation on the flow characteristics in a cover-plate pre-swirl system. The Reynolds-averaged Navier-Stokes equations, coupled with the standard k-ε turbulent model, are adopted and solved. With the inlet total pressure and total temperature being constant, the influences of the temperature reduction and flow resistance by changing pressure ratios and rotational Reynolds numbers were conducted. Flow features in the pre-swirl nozzle, pre-swirl cavity, receiver hole and cover-plate cavity were summarized. The results obtained in this study indicate that the pressure ratio and rotational Reynolds number have a significant influence on the vortex structure of the pre-swirl system. As the air is accelerated by the pre-swirl nozzle, the difference of circumferential velocity between the air and the rotational domain would be reduced, and the static temperature of the air would be decreased. The pressure drop in the pre-swirl system mainly occurs in the pre-swirl nozzle and the pre-swirl cavity. In addition, with the increase of the pressure ratio, the air mass flow rate and the circumferential velocity of the air out of the nozzle increased, thereby leading to an increment in temperature reduction. Moreover, with the increasing of the rotational Reynolds number, the dimensionless mass flow rate and temperature reduction of the pre-swirl system, which are mainly determined by the flow incidence angle of cooling air at the receiver hole, will first increase to a maximum and then decrease.

scholarly journals Experimental Performance of a Solar Air Collector with a Perforated Back Plate in New Zealand

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1415 ◽  
Author(s):  
Yu Wang ◽  
Mikael Boulic ◽  
Robyn Phipps ◽  
Manfred Plagmann ◽  
Chris Cunningham
Keyword(s):  
Wind Speed ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Absorber Layer ◽  
Cover Plate ◽  
Solar Air Heater ◽  
Air Mass ◽  
Back Plate

This study investigates the thermal efficiency of a solar air heater (SAH), when it was mounted on a custom-made support frame, and was operated under different air mass flow rate. This SAH is composed of a transparent polycarbonate cover plate, a felt absorber layer, a perforated aluminium back plate and an aluminium frame. The ambient inlet air of this SAH is heated as it passes through the perforated back plate and over the felt absorber layer. The heated air is blown out through the outlet. Studies of SAHs with a similar design to this SAH were not found in the literature. The experiment was carried out at Massey University, Auckland campus, NZ (36.7° S, 174.7° E). The global horizontal solar irradiance, the ambient temperature and the wind speed were recorded using an on-site weather station. Temperature and velocity of the air at the outlet were measured using a hot wire anemometer. During the experiment, the air mass flow rate was between 0.022 ± 0.001 kg/s and 0.056 ± 0.005 kg/s. Results showed that when the SAH was operated at the airflow between 0.0054 kg/s and 0.0058 kg/s, the inlet air temperature and the wind speed (between 0 and 6.0 m/s) did not impact the temperature difference between the outlet air and the inlet air. The thermal efficiency of the SAH increased from 34 ± 5% at the airflow between 0.021 kg/s and 0.023 kg/s, to 47 ± 6% at the airflow ranging from 0.032 kg/s to 0.038 kg/s, to 71 ± 4% at the airflow of 0.056 ± 0.005 kg/s. The maximum thermal efficiency of 75% was obtained at the airflow of 0.057 kg/s. The effective efficiency of the SAH was 32 ± 5% at the airflow between 0.021 kg/s and 0.023 kg/s, 42 ± 6% at the airflow ranging from 0.032 kg/s to 0.038 kg/s, and 46 ± 11% at the airflow of 0.056 ± 0.005 kg/s.

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.

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