|
|
Influence of boundary walls on the flow from the ventilation outlet
Molčan, Filip ; Jícha, Miroslav (referee) ; Jedelský, Jan (advisor)
The goal of this work is to experimentally assess the influence of limiting walls of Škoda Octavia 3 automobile cabin to the air jet flowing from the right-front situated automotive vent which is part of a car dashboard. The experiment is performed by the smoke visualization method. There is a single construction option measured for an experiment. The setup of the vanes direction and the air flow rate are modified for this option. The experiment is divided into two phases. In the first phase, the visualization of the free air flow is conducted. In the second phase, exit plates are constructed and consequently, the visualization of the wall-jet flow is conducted. The results of both are compared to each other. The results imply that the influence of the surrounding surfaces must be taken into account with the increasing flow rate for the vanes set in the direction of upper-right, middle-right, and middle-middle. There is a direct interaction between the flow and exit plates (the flow impact, the Coanda effect). The free flow does not contain the information about the mutual interaction between the flow and the exit plates, as it is in the case of the wall-jet flow. In the case of the wall-jet flow, the opening of the flow takes place due to the effect of the impact and the subsequential suction caused by the Coanda effect. The exit plates substituting the car dashboard and the front window contribute to the prevention of the air intake from surrounding space and consequently to earlier flow opening from the vent. The present work also contains the measurement methodology and the image evaluation, the comparison with previous free flow measurements (70% match) and the comparison to the measurement of hot-wire anemometry method.
|
|
|
Annular Impinging Jets and an Active Control of Hysteretic Effects
Devani, Yogendrasasidhar ; Antošová, Zuzana ; Trávníček, Zdeněk
An annular impinging air jet with and without flow control was studied experimentally using measurements of the wall pressure and flow velocity by the Pitot probe. To investigate flow control swirling effects, eight synthetic jets were generated from the nozzle center body. The experiments cover Reynolds numbers 4000–10,000 (evaluated from the outer exit diameter of the annular nozzle). For Re<9000, the bistability and hysteresis were identified and two different flow field patterns (A, B) were found under the same boundary conditions. For higher Re>9000, the hysteresis were not found.
|
|
|
Annular impinging jets and an active control of hysteretic effects
Devani, Yogendrasasidhar ; Antošová, Zuzana ; Trávníček, Zdeněk
An annular air jet with and without flow control was studied experimentally using flow visualization and measurements of the wall pressure and flow velocity by the Pitot and Prandtl probes and the hot-wire anemometer. To investigate flow control swirling effects, eight synthetic jets were generated from the annular nozzle center body.The experiments cover Reynolds numbers 4000–10000 (evaluated from the outer exit diameter of the annular nozzle). For Re<9000, the bistability and hysteresis were identified and two different flow field patterns (A and B) were found under the same boundary conditions. For A pattern, a small recirculation area (bubble) of separated flow is attached to the nozzle center body. For B pattern, a large recirculation area of separated flow bridges entire nozzle-to-wall distance. For higher Re > 9000, the bistability and hysteresis were not found.Flow control swirling effects causes suppression of the hysteresis. Moreover, weak flow control causes that the entire annular jet is forced into a precessing motion.
|
|
|
Influence of boundary walls on the flow from the ventilation outlet
Molčan, Filip ; Jícha, Miroslav (referee) ; Jedelský, Jan (advisor)
The goal of this work is to experimentally assess the influence of limiting walls of Škoda Octavia 3 automobile cabin to the air jet flowing from the right-front situated automotive vent which is part of a car dashboard. The experiment is performed by the smoke visualization method. There is a single construction option measured for an experiment. The setup of the vanes direction and the air flow rate are modified for this option. The experiment is divided into two phases. In the first phase, the visualization of the free air flow is conducted. In the second phase, exit plates are constructed and consequently, the visualization of the wall-jet flow is conducted. The results of both are compared to each other. The results imply that the influence of the surrounding surfaces must be taken into account with the increasing flow rate for the vanes set in the direction of upper-right, middle-right, and middle-middle. There is a direct interaction between the flow and exit plates (the flow impact, the Coanda effect). The free flow does not contain the information about the mutual interaction between the flow and the exit plates, as it is in the case of the wall-jet flow. In the case of the wall-jet flow, the opening of the flow takes place due to the effect of the impact and the subsequential suction caused by the Coanda effect. The exit plates substituting the car dashboard and the front window contribute to the prevention of the air intake from surrounding space and consequently to earlier flow opening from the vent. The present work also contains the measurement methodology and the image evaluation, the comparison with previous free flow measurements (70% match) and the comparison to the measurement of hot-wire anemometry method.
|
|
| |
|
| |
|
|
HYBRID-SYNTHETIC IMPINGING JETS
Tesař, Václav
Impinging jets can achieve the highest convective heat or mass transfer rate. An increase beyond present limits is possible by pulsation of the flow. The extreme case of the synthetic jets could be particularly effective – were there not the re-ingestion of the fluid. A solution brings the new concept of non-zero time mean hybrid synthetic jet.
|
|
| |
|
|
Nestacionární charakteristiky impaktního proudění do korýtkové kavity
Knob, Martin ; Antoš, Pavel ; Adamec, J.
In this contribution, the unsteady behaviour of a jet, impinging into a trough cavity is described. The mechanism of the switching of the jet is clarified and the effect of the impingement angle is discussed. The problem was studied both experimentally and numerically. The numerical investigation is performed using a commercial package Fluent 6.1, while the experimental data are obtained using the hot- wire probe. The experimental and the numerical data are compared and discussed.
|
|
| |
guest ::
