scholarly journals Study of a segmented ventilation system of the brake disc and determination of the aerodynamic and heat exchange characteristics of the airflow

2022 ◽  
Vol 25 (6) ◽  
pp. 720-732
Author(s):  
P. A. Polyakov
Keyword(s):  
Boundary Layer ◽  
Heat Exchange ◽  
Work Performance ◽  
Heat Dissipation ◽  
Air Flow ◽  
Ventilation System ◽  
Aerodynamic Characteristics ◽  
Design Parameters ◽  
Brake Disc ◽  
Cfd Modelling

This study aims determine a relationship between the aerodynamic and heat exchange characteristics of the air flow in a segmented ventilation system of the brake disc with improved heat dissipation in the boundary layer of the air flow. Classical equations of heat and mass transfer in the boundary layer of the air flow cooling the brake disc ventilation chamber were used. The cooling performance of the system was assessed using the method of similarity. The obtained theoretical findings were confirmed by CFD-modelling. Mathematical models were developed for vented discs with both continuous grooves and slotted grooves. A criterion for assessing the performance of brake disc ventilation systems was proposed, consisting in turbulization of the air flow inside the device under study. According to the obtained analytical dependencies, a 20-fold acceleration of the air flow decreases the turbulization parameter by 1.24 times. An increase in the temperature difference in the boundary layer by 8 times leads to an increase in the turbulization parame-ter by 86.2 times. Using the criterion proposed for assessing the work performance, the aerodynamic and heat exchange characteristics of the system under study were calculated. As a result, a relationship between the design parameters of the segmented ventilation system and improved heat dissipation in the boundary layer of the cooling air flow is proposed. The conducted CFD modelling confirmed the aerodynamic characteristics of the system under study obtained theoretical-ly. This mathematical model together with the turbulization parameter can be used when both developing modern vented brake discs and assessing the existing cooling systems of friction units in order to minimize the possibility of reduced heat exchange processes.

Parametric Analysis of the Boundary Layer of the Air Flow of the Ventilation Duct of the Brake Disc

2021 ◽  
pp. 493-504
Author(s):  
Artem Litvinov ◽  
Ivan Yaitskov ◽  
Pavel Polyakov ◽  
Alexey Golikov ◽  
Evgeny Fedotov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Parametric Analysis ◽  
Air Flow ◽  
Brake Disc ◽  
Ventilation Duct

scholarly journals Experimental Investigation of the Air Exchange Effectiveness of Push-Pull Ventilation Devices

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5817
Author(s):  
Sven Auerswald ◽  
Carina Hörberg ◽  
Thibault Pflug ◽  
Jens Pfafferott ◽  
Constanze Bongs ◽  
...  
Keyword(s):  
Heat Dissipation ◽  
Residential Buildings ◽  
Air Flow ◽  
Operation Mode ◽  
Ventilation System ◽  
Field Measurements ◽  
Gas Analysis ◽  
Decentralised Systems ◽  
Set Up ◽  
Air Exchange

The increasing installation numbers of ventilation units in residential buildings are driven by legal objectives to improve their energy efficiency. The dimensioning of a ventilation system for nearly zero energy buildings is usually based on the air flow rate desired by the clients or requested by technical regulations. However, this does not necessarily lead to a system actually able to renew the air volume of the living space effectively. In recent years decentralised systems with an alternating operation mode and fairly good energy efficiencies entered the market and following question was raised: “Does this operation mode allow an efficient air renewal?” This question can be answered experimentally by performing a tracer gas analysis. In the presented study, a total of 15 preliminary tests are carried out in a climatic chamber representing a single room equipped with two push-pull devices. The tests include summer, winter and isothermal supply air conditions since this parameter variation is missing till now for push-pull devices. Further investigations are dedicated to the effect of thermal convection due to human heat dissipation on the room air flow. In dependence on these boundary conditions, the determined air exchange efficiency varies, lagging behind the expected range 0.5 < εa < 1 in almost all cases, indicating insufficient air exchange including short-circuiting. Local air exchange values suggest inhomogeneous air renewal depending on the distance to the indoor apertures as well as the temperature gradients between in- and outdoor. The tested measurement set-up is applicable for field measurements.

EFFECTS OF BRAKE DISC GEOMETRICAL PARAMETERS AND CONFIGURATIONS ON AUTOMOTIVE BRAKING THERMAL PERFORMACE

2008 ◽  
Vol 32 (2) ◽  
pp. 313-324 ◽  
Author(s):  
Zhongzhe Chi ◽  
Greg F. Naterer ◽  
Yuping He
Keyword(s):  
Numerical Simulations ◽  
Thermal Performance ◽  
Air Flow ◽  
Aerodynamic Characteristics ◽  
Geometrical Parameters ◽  
Brake Disc ◽  
Disc Brakes ◽  
Parametric Studies ◽  
Flow Through ◽  
Brake Rotors

This paper examines the effects of geometrical parameters of pillar post rotors on the thermal performance of automotive vehicle brakes. The thermal performance of vented disc brakes strongly depends on the aerodynamic characteristics of the air flow through the rotor passages. These air flow passages are determined by the geometrical parameters of the brake rotors. In this study, different pillar post rotor models are considered and the corresponding numerical simulations are performed, in order to investigate the effects of various geometrical parameters on the thermal performance. These geometrical parameters include the shape, size, and distribution of a pillar post. The new insight from these parametric studies provides useful guidelines to optimize the geometry of pillar post rotors of automotive vehicles.

Experimental Study of Heat Transfer in a Strongly Cooled Boundary Layer in Supersonic Air Flow

2002 ◽  
Vol 33 (3-4) ◽  
pp. 4
Author(s):  
E. V. Gurentsov ◽  
V. K. Shikov ◽  
E. B. Eigenson
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Air Flow

DESIGN AND THERMAL ANALYSIS OF BRAKE ROTOR WITH DIFFERENT MATERIALS

2020 ◽  
Vol 15 (2) ◽  
Author(s):  
Sugunarani S ◽  
Santhosh V
Keyword(s):  
Temperature Distribution ◽  
Heat Dissipation ◽  
Brake Disc ◽  
Element Analysis ◽  
Analysis Techniques ◽  
Engineering Software ◽  
The Finite Element Analysis ◽  
Brake Rotor ◽  
Grey Cast ◽  
Aluminium Metal

This work deals with the analysis of heat generation and dissipation in the disc brake of a car during braking and the following release period by using computer-aided engineering software for three different materials of the rotor disc and brake pad. The objective of this work is to analyze the temperature distribution of rotor disc during operation using COMSOL Multiphysics. The work uses the finite element analysis techniques to calculate and predict the temperature distribution on the brake disc and to identify the critical temperature of the brake rotor disc. Conduction, convection and radiation of heat transfer have been analyzed. The results obtained from the analysis indicates that different material on the same retardation of the car during braking shows different temperature distribution. A comparative study was made between grey cast iron (GCI), Aluminium Metal Matrix Composite (AMMC), Alloy steel materials are used for brake disc and the best material for making brake disc based on the rate of heat dissipation have been suggested.

Removal of trichloroethylene and trichloroethane using a novel hollow-fibre gas-permeable membrane

2003 ◽  
Vol 3 (5-6) ◽  
pp. 67-72
Author(s):  
S. Takizawa ◽  
T. Win
Keyword(s):  
Boundary Layer ◽  
Flow Regime ◽  
Removal Efficiency ◽  
Residence Time ◽  
Flow Rate ◽  
Air Flow ◽  
Hollow Fibre ◽  
Permeation Rate ◽  
Permeable Membrane ◽  
Diffusional Boundary Layer

In order to evaluate effects of operational parameters on the removal efficiency of trichloroethylene and 1,1,1-trichloroethene from water, lab-scale experiments were conducted using a novel hollow-fibre gaspermeable membrane system, which has a very thin gas-permeable membrane held between microporous support membranes. The permeation rate of chlorinated hydrocarbons increased at higher temperature and water flow rate. On the other hand, the effects of the operational conditions in the permeate side were complex. When the permeate side was kept at low pressure without sweeping air (pervaporation), the removal efficiency of chlorinated hydrocarbon, as well as water permeation rate, was low probably due to lower level of membrane swelling on the permeate side. But when a very small amount of air was swept on the membrane (air perstripping) under a low pressure, it showed a higher efficiency than in any other conditions. Three factors affecting the permeation rate are: 1) reduction of diffusional boundary layer within the microporous support membrane, 2) air/vapour flow regime and short cutting, and 3) the extent of membrane swelling on the permeate side. A higher air flow, in general, reduces the diffusional boundary layer, but at the same time disrupts the flow regime, causes short cutting, and makes the membrane dryer. Due to these multiple effects on gas permeation, there is an optimum operational condition concerning the vacuum pressure and the air flow rate. Under the optimum operational condition, the residence time within the hollow-fibre membrane to achieve 99% removal of TCE was 5.25 minutes. The log (removal rate) was linearly correlated with the average hydraulic residence time within the membrane, and 1 mg/L of TCE can be reduced to 1 μg/L (99.9% removal).

Air flow quality analysis of an open-circuit boundary layer wind tunnel and comparison with a closed-circuit wind tunnel

2020 ◽  
Vol 32 (12) ◽  
pp. 125120
Author(s):  
María Jiménez-Portaz ◽  
Luca Chiapponi ◽  
María Clavero ◽  
Miguel A. Losada
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Air Flow ◽  
Open Circuit ◽  
Closed Circuit ◽  
Quality Analysis ◽  
Flow Quality

Modelling Vortex Generating Jet-Induced Transition in Low-Pressure Turbines

2013 ◽  
Author(s):  
Florian Herbst ◽  
Andreas Fiala ◽  
Joerg R. Seume
Keyword(s):  
Boundary Layer ◽  
Cross Flow ◽  
Transition Process ◽  
Low Pressure ◽  
Boundary Layer Transition ◽  
Quantitative Prediction ◽  
Design Parameters ◽  
Transition Model ◽  
Layer Transition ◽  
Wall Flows

The current design of low-pressure turbines (LPTs) with steady-blowing vortex generating jets (VGJ) uses steady computational fluid dynamics (CFD). The present work aims to support this design approach by proposing a new semi-empirical transition model for injection-induced laminar-turbulent boundary layer transition. It is based on the detection of cross-flow vortices in the boundary layer which cause inflectional cross-flow velocity profiles. The model is implemented in the CFD code TRACE within the framework of the γ-Reθ transition model and is a reformulated, re-calibrated, and extended version of a previously presented model. It is extensively validated by means of VGJ as well as non-VGJ test cases capturing the local transition process in a physically reasonable way. Quantitative aerodynamic design parameters of several VGJ configurations including steady and periodic-unsteady inflow conditions are predicted in good accordance with experimental values. Furthermore, the quantitative prediction of end-wall flows of LPTs is improved by detecting typical secondary flow structures. For the first time, the newly derived model allows the quantitative design and optimization of LPTs with VGJs.

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