The Experts below are selected from a list of 4458 Experts worldwide ranked by ideXlab platform

Fei Yu Cheng - One of the best experts on this subject based on the ideXlab platform.

  • Numerical study on Aerodynamic Characteristics of high-speed trains with considering thermal-flow coupling effects
    JVE International, 2017
    Co-Authors: Ai Mi Yang, Hong Wei Xing, Ling Zhang, Li Jing Feng, Fei Yu Cheng
    Abstract:

    In order to conduct in-depth researches on rationality of air conditioning system equipment of a high-speed train as well as its pipeline system design, working conditions of the air conditioning system and distribution of Aerodynamic Characteristics including pressure, velocity and temperature in high speed trains should be computed carefully at the design stage. Therefore, the finite volume method was used to solve a governing equation of computational fluid dynamics. The Aerodynamic Characteristics of pipelines of the air conditioning system and the complete high speed train were computed, so the indoor distribution of wind velocity, temperature and gas concentration (carbon oxide, carbon dioxide, nitrogen and so forth) was obtained. The flow field index and the thermal comfort index were used to evaluate the indoor thermal comfort degree. In this way, whether rationality of the air conditioning system design and indoor Aerodynamic Characteristic could satisfy requirements for design specifications can be analyzed. Results show that: Under winter or summer working conditions, wind velocity was relatively high at the passageway door, where the maximum wind velocity was more than 1 m/s and would make passengers uncomfortable. Air flow velocity outside comfortable regions was more than 0.05 m/s, satisfying UIC553 standards. Velocity distribution was basically the same indoors, where wind velocity was large at positions perpendicular to the air supply hole, and the maximum wind velocity was more than 1 m/s, but wind velocity was uniform in the passenger region, which was basically lower than 0.2 m/s and satisfied UIC553 standards. In summer and winter working conditions, distribution of pressure, velocity and temperature was not uniform, where the maximum temperature gradient was near the air inlet in the compartment. Air components in the compartment satisfied requirements for comfort. The most uncomfortable regions in the compartment were concentrated at the passageway. Air supply holes distributed symmetrically on the train roof caused high air flow intensity, high wind velocity, low temperature and high humidity at the passageway in the compartment, so the thermal comfort was low, and it is feasible to adjust the layout of air supply holes appropriately

Alain Pelletier - One of the best experts on this subject based on the ideXlab platform.

  • the unsteady Aerodynamics of slender wings and aircraft undergoing large amplitude maneuvers
    Progress in Aerospace Sciences, 2003
    Co-Authors: Robert C Nelson, Alain Pelletier
    Abstract:

    Abstract Aircraft that maneuver through large angles of attack will experience large regions of flow separation over the wing and fuselage. The separated flow field is characterized by unsteadiness and strong vortical flow structures that can interact with various components of the aircraft. These complicated flow interactions are the primary cause of most flight dynamic instabilities, airload nonlinearities and flow field time lags. The Aerodynamic and the vortical flow structure over simple delta wings undergoing either a pitching or rolling motion is presented. This article reviews experimental information on the flow structure over delta wings and complete aircraft configurations. First, the flow structure of leading-edge vortices and their influence on delta wing Aerodynamics for stationary models is presented. This is followed by a discussion of the effect of large amplitude motion on the vortex structure and Aerodynamic Characteristic of pitching and rolling delta wings. The relationship between the flow structure and the unsteady airloads is reviewed. The unsteady motion of the delta wing results in a modification of the flow field. Delays in flow separation, vortex formation, vortex position and the onset of vortex breakdown are all affected by the model motion. These flow changes cause a corresponding modification in the Aerodynamic loads. Data is presented which shows the importance of flow field hysteresis in either vortex position or breakdown and the influence on the Aerodynamic Characteristics of a maneuvering delta wing. The free-to-roll motion of a double-delta wing is also presented. The complicated flow structure over a double-delta wing gives rise to damped, chaotic and wing rock motions as the angle of attack is increased. The concept of a critical state is discussed and it is shown that crossing a critical state produces large transients in the dynamic airloads. Next, several aircraft configurations are examined to show the importance of unsteady Aerodynamics on the flight dynamics of aircraft maneuvering at large angles of attack. The rolling Characteristics of the F-18 and X-31 configurations are examined. The influence of the vortical flow structure on the rolling motion is established. Finally, a brief discussion of nonlinear Aerodynamic modeling is presented. The importance of critical states and the transient Aerodynamics associated with crossing a critical state are examined.

Ai Mi Yang - One of the best experts on this subject based on the ideXlab platform.

  • Numerical study on Aerodynamic Characteristics of high-speed trains with considering thermal-flow coupling effects
    JVE International, 2017
    Co-Authors: Ai Mi Yang, Hong Wei Xing, Ling Zhang, Li Jing Feng, Fei Yu Cheng
    Abstract:

    In order to conduct in-depth researches on rationality of air conditioning system equipment of a high-speed train as well as its pipeline system design, working conditions of the air conditioning system and distribution of Aerodynamic Characteristics including pressure, velocity and temperature in high speed trains should be computed carefully at the design stage. Therefore, the finite volume method was used to solve a governing equation of computational fluid dynamics. The Aerodynamic Characteristics of pipelines of the air conditioning system and the complete high speed train were computed, so the indoor distribution of wind velocity, temperature and gas concentration (carbon oxide, carbon dioxide, nitrogen and so forth) was obtained. The flow field index and the thermal comfort index were used to evaluate the indoor thermal comfort degree. In this way, whether rationality of the air conditioning system design and indoor Aerodynamic Characteristic could satisfy requirements for design specifications can be analyzed. Results show that: Under winter or summer working conditions, wind velocity was relatively high at the passageway door, where the maximum wind velocity was more than 1 m/s and would make passengers uncomfortable. Air flow velocity outside comfortable regions was more than 0.05 m/s, satisfying UIC553 standards. Velocity distribution was basically the same indoors, where wind velocity was large at positions perpendicular to the air supply hole, and the maximum wind velocity was more than 1 m/s, but wind velocity was uniform in the passenger region, which was basically lower than 0.2 m/s and satisfied UIC553 standards. In summer and winter working conditions, distribution of pressure, velocity and temperature was not uniform, where the maximum temperature gradient was near the air inlet in the compartment. Air components in the compartment satisfied requirements for comfort. The most uncomfortable regions in the compartment were concentrated at the passageway. Air supply holes distributed symmetrically on the train roof caused high air flow intensity, high wind velocity, low temperature and high humidity at the passageway in the compartment, so the thermal comfort was low, and it is feasible to adjust the layout of air supply holes appropriately

Ling Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Numerical study on Aerodynamic Characteristics of high-speed trains with considering thermal-flow coupling effects
    JVE International, 2017
    Co-Authors: Ai Mi Yang, Hong Wei Xing, Ling Zhang, Li Jing Feng, Fei Yu Cheng
    Abstract:

    In order to conduct in-depth researches on rationality of air conditioning system equipment of a high-speed train as well as its pipeline system design, working conditions of the air conditioning system and distribution of Aerodynamic Characteristics including pressure, velocity and temperature in high speed trains should be computed carefully at the design stage. Therefore, the finite volume method was used to solve a governing equation of computational fluid dynamics. The Aerodynamic Characteristics of pipelines of the air conditioning system and the complete high speed train were computed, so the indoor distribution of wind velocity, temperature and gas concentration (carbon oxide, carbon dioxide, nitrogen and so forth) was obtained. The flow field index and the thermal comfort index were used to evaluate the indoor thermal comfort degree. In this way, whether rationality of the air conditioning system design and indoor Aerodynamic Characteristic could satisfy requirements for design specifications can be analyzed. Results show that: Under winter or summer working conditions, wind velocity was relatively high at the passageway door, where the maximum wind velocity was more than 1 m/s and would make passengers uncomfortable. Air flow velocity outside comfortable regions was more than 0.05 m/s, satisfying UIC553 standards. Velocity distribution was basically the same indoors, where wind velocity was large at positions perpendicular to the air supply hole, and the maximum wind velocity was more than 1 m/s, but wind velocity was uniform in the passenger region, which was basically lower than 0.2 m/s and satisfied UIC553 standards. In summer and winter working conditions, distribution of pressure, velocity and temperature was not uniform, where the maximum temperature gradient was near the air inlet in the compartment. Air components in the compartment satisfied requirements for comfort. The most uncomfortable regions in the compartment were concentrated at the passageway. Air supply holes distributed symmetrically on the train roof caused high air flow intensity, high wind velocity, low temperature and high humidity at the passageway in the compartment, so the thermal comfort was low, and it is feasible to adjust the layout of air supply holes appropriately

Hong Wei Xing - One of the best experts on this subject based on the ideXlab platform.

  • Numerical study on Aerodynamic Characteristics of high-speed trains with considering thermal-flow coupling effects
    JVE International, 2017
    Co-Authors: Ai Mi Yang, Hong Wei Xing, Ling Zhang, Li Jing Feng, Fei Yu Cheng
    Abstract:

    In order to conduct in-depth researches on rationality of air conditioning system equipment of a high-speed train as well as its pipeline system design, working conditions of the air conditioning system and distribution of Aerodynamic Characteristics including pressure, velocity and temperature in high speed trains should be computed carefully at the design stage. Therefore, the finite volume method was used to solve a governing equation of computational fluid dynamics. The Aerodynamic Characteristics of pipelines of the air conditioning system and the complete high speed train were computed, so the indoor distribution of wind velocity, temperature and gas concentration (carbon oxide, carbon dioxide, nitrogen and so forth) was obtained. The flow field index and the thermal comfort index were used to evaluate the indoor thermal comfort degree. In this way, whether rationality of the air conditioning system design and indoor Aerodynamic Characteristic could satisfy requirements for design specifications can be analyzed. Results show that: Under winter or summer working conditions, wind velocity was relatively high at the passageway door, where the maximum wind velocity was more than 1 m/s and would make passengers uncomfortable. Air flow velocity outside comfortable regions was more than 0.05 m/s, satisfying UIC553 standards. Velocity distribution was basically the same indoors, where wind velocity was large at positions perpendicular to the air supply hole, and the maximum wind velocity was more than 1 m/s, but wind velocity was uniform in the passenger region, which was basically lower than 0.2 m/s and satisfied UIC553 standards. In summer and winter working conditions, distribution of pressure, velocity and temperature was not uniform, where the maximum temperature gradient was near the air inlet in the compartment. Air components in the compartment satisfied requirements for comfort. The most uncomfortable regions in the compartment were concentrated at the passageway. Air supply holes distributed symmetrically on the train roof caused high air flow intensity, high wind velocity, low temperature and high humidity at the passageway in the compartment, so the thermal comfort was low, and it is feasible to adjust the layout of air supply holes appropriately