Influence of Longitudinal Fin Tubes Arrangement in LNG Ambient Air Vaporizers on the Wind Load

The article presents the results of computational fluid dynamics (CFD) analysis of the wind action on liquefied natural gas (LNG) ambient air vaporizers (AAVs). A study concerning AAV with a 6 × 6 tubes array is presented to demonstrate how the distribution of longitudinal finned tubes and wind direction affect the average load and wind pressure acting on the vaporizer structure. The main goal of the study is to estimate the wind load on the structure and wind pressure on individual tubes depending on the pitch of the tubes arrangement. The above parameters are crucial for the strength analysis of the vaporizer structure. The derived analysis results provide important data on the variation of pressure on individual tubes, wind velocity inside AVV structure and indicate a significant increase in the average wind load acting on the structure for a wind direction of 45 degrees compared to a perpendicular direction.

The characteristics of weather-related wind load parameters and wind 2 power quality over the Dabanchen strong gale area

Analysis of data from cup and ultrasonic anemometers on a 100 m-tall wind mast in the Dabanchen Canyon reveals that the turbulence intensities, gust factors, and peak factors measured by cup anemometers tend to be severely undervalued compared to longitudinal values from an ultrasonic anemometer, and onsite three-dimensional measurement data are preferred for weather-related wind load calculation. This difference is related to the rotating responses of cup anemometers during wind speed acceleration or deceleration and the higher vertical fluctuation speeds driven by dynamic interactions with the sloped canyon terrain. The higher lateral turbulence is key consideration for determining wind turbine classes in Danbanchen strong wind area. The longitudinal gust and peak factors under wind speeds exceeding 25.0 m s−1 are comparable with those of typhoon-prone open, flat regions. The chances of high turbulence and unstable stratification convective processes are very high; thus, wind power collection efficiencies are not high. Except the longitudinal turbulence integral scale, China’s wind-resistance codes are not applicable due to occasional undesirable strong gales with extraordinary turbulence structures. The measured vertical power spectral density of fluctuating wind in the high-frequency domain cannot reflect the rapidly adapting features of the vast terrain under strong gales.

The characteristics of weather-related wind load parameters and wind power quality over the Dabanchen strong gale area

Analysis of data from cup and ultrasonic anemometers on a 100 m-tall wind mast in the Dabanchen Canyon reveals that the turbulence intensities, gust factors, and peak factors measured by cup anemometers tend to be severely undervalued compared to longitudinal values from an ultrasonic anemometer, and onsite three-dimensional measurement data are preferred for weather-related wind load calculation. This difference is related to the rotating responses of cup anemometers during wind speed acceleration or deceleration and the higher vertical fluctuation speeds driven by dynamic interactions with the sloped canyon terrain. The higher lateral turbulence is key consideration for determining wind turbine classes in Danbanchen strong wind area. The longitudinal gust and peak factors under wind speeds exceeding 25.0 m s−1 are comparable with those of typhoon-prone open, flat regions. The chances of high turbulence and unstable stratification convective processes are very high; thus, wind power collection efficiencies are not high. Except the longitudinal turbulence integral scale, China’s wind-resistance codes are not applicable due to occasional undesirable strong gales with extraordinary turbulence structures. The measured vertical power spectral density of fluctuating wind in the high-frequency domain cannot reflect the rapidly adapting features of the vast terrain under strong gales.

Ultracompact Dual-Polarized Cross-Dipole Antenna for 5G Base Station Array of Low Wind Load

Very high wind loads represent one of the major problems for the ultralarge-scale 5G base station array at the sub-6 GHz band, where dozens of or hundreds of antennas are used. An ultracompact dual-polarized cross-dipole antenna with an extremely small overall projected area is presented. The array with low wind load is realized by miniaturized cross dipoles and the replacement of the traditional ground plane with a defected ground structure (DGS) and metal mesh reflector. The DGS is utilized to realize size reduction and isolation enhancement. The projected area of the antenna is reduced by 70%. Therefore, each antenna in the array can be independently packaged using a streamlined radome with a low wind load. And the inter-radome spacing is large enough to make holes that are used to further reduce wind load. The antenna prototype is designed, fabricated, and measured for the sub-1 GHz band. The measured results show that the impedance bandwidth is 680-970 MHz, the polarization isolation is higher than 20 dB, and the gain is around 6.5 dBi. It is verified that the proposed ultracompact antenna of high radiation performance is very suitable for an ultralarge-scale array of low wind load in a 5G base station.

Ultracompact Dual-Polarized Cross-Dipole Antenna for 5G Base Station Array of Low Wind Load

Very high wind loads represent one of the major problems for the ultralarge-scale 5G base station array at the sub-6 GHz band, where dozens of or hundreds of antennas are used. An ultracompact dual-polarized cross-dipole antenna with an extremely small overall projected area is presented. The array with low wind load is realized by miniaturized cross dipoles and the replacement of the traditional ground plane with a defected ground structure (DGS) and metal mesh reflector. The DGS is utilized to realize size reduction and isolation enhancement. The projected area of the antenna is reduced by 70%. Therefore, each antenna in the array can be independently packaged using a streamlined radome with a low wind load. And the inter-radome spacing is large enough to make holes that are used to further reduce wind load. The antenna prototype is designed, fabricated, and measured for the sub-1 GHz band. The measured results show that the impedance bandwidth is 680-970 MHz, the polarization isolation is higher than 20 dB, and the gain is around 6.5 dBi. It is verified that the proposed ultracompact antenna of high radiation performance is very suitable for an ultralarge-scale array of low wind load in a 5G base station.