• Characteristics of near-nozzle spray development from a fouled GDI injector

      Zhou, Jianwei; Pei, Yiqiang; Peng, Zhijun; Zhang, Yanfeng; Qin, Jing; Wang, Li; Liu, Changwen; Zhang, Xiaoyu; Tianjin University; University of Bedfordshire; et al. (Elsevier Ltd, 2018-03-16)
      The near-nozzle spray development of a typical fouled gasoline direct injection (GDI) injector was investigated. The fouled injector had been used in a stratified-charge combustion GDI engine and showed typical characteristics, such as accumulated deposits inside and around the nozzles and a reduced flow rate of 2.9–5.7%. Back-illumination and Mie-scattering methods were employed in spray experiments, in conjunction with a high speed camera and a macro lens, to assess the near-nozzle spray behaviors. The experimental results show that at all injection pressures tested, the interaction between deposits and spray led to several poor spray behaviors during the full injection evolution, including spray distortion, residual fuel storage in the nozzles and deposits layer, liquid splashing, the formation of ligament and large droplets and tip wetting/dripping. These effects all may result in high soot emissions. The after-injection stage of the fouled injector produced more liquid ligaments than that of the new injector. It was also found that high injection pressures did not improve atomization during after-injection, nor reduce the amounts of ligaments and droplet clusters beyond the main spray boundary. The plume width and projected spray area of a single nozzle in the fouled injector were decreased by 5–7% and 17–20%, respectively, due to fuel flow losses. The delays in the start of injection and end of injection were approximately 20 μs and 30–40 μs, respectively.
    • Life Cycle Assessment (LCA) of BEV's environmental benefits for meeting the challenge of ICExit (Internal Combustion Engine Exit)

      Zheng, Ge; Peng, Zhijun; University of Essex; University of Bedfordshire (Elsevier Ltd, 2021-02-19)
      Based on necessary literature review, LC (Life Cycle) emissions, in particular LCCO2 (Life Cycle CO2) emissions, of BEVs (Battery Electric Vehicles) have been assessed and compared with the most efficient ICEVs (Internal Combustion Engine Vehicles), such as non-plug-in HEVs (Hybrid Electric Vehicles) and diesel cars. By considering CO2 emissions from vehicle production, vehicle recycle and the entire process of energy flow (from the mining of the energy source to a vehicle being driven), LCCO2 emission models of BEVs and ICEVs were built. For comparing between BEVs and ICEVs in terms of their LC emissions, a new measure named SRPR (Square Root of Power and Range) has been proposed for correctly reflecting the powertrain's main performance. Results show that, although BEVs have much lower ECR (Energy Consumption Rate) than non-plug-in HEV and diesel cars, their LCCO2 are very variable, and are very dependent on LCCO2 of power generation mix of specific country. In some countries where thermal power generation, in particular coal power generation, is still dominant, BEVs’ LCCO2 are apparently higher than ICEVs. If a country would like to have their BEVs operating lower LCCO2 than ICEVs, the overall average LCCO2 from their power generation mix should be at least at the level about 320 g/kWh. As a case study, by analysing the power generation development trend and the BEV development trend in China, it suggests that their aim for developing BEVs to have lower LCCO2 than ICEVs in next two or three decades would be very difficult to meet. If they like to put priority on the reduction of LCCO2 of ground vehicles, BEVs could not be widely promoted in China until they made their power generation clean enough, probably at least in next 20 even 30 years. Finally, BEVs’ other LC pollutant emissions, such as NOx (Nitrogen Oxides), PM (Particulate Matters), SOx (Sulphur Oxides) would not be a very serious problem if those thermal power generations are equipped with adequate exhaust aftertreatment for removing those pollutant emissions.
    • Wrinkle measurement in glass-carbon hybrid laminates comparing ultrasonic techniques: a case study

      Larrañaga-Valsero, Beatriz; Smith, Robert A.; Tayong-Boumda, Rostand; Fernández-López, Antonio; Güemes, Alfredo; Universidad Politécnica de Madrid; University of Bristol (Elsevier Ltd, 2018-08-15)
      Wrinkles, (also known as out-of-plane waviness) are, unfortunately, a common phenomenon that has caused some wind-turbine blades to unexpectedly fail in service. Being able to detect the wrinkles while in the factory will reduce the risk of catastrophic failure and characterising the wrinkles would minimise the repaired area, thus increasing the efficiency of the repair and the design. This work compares the effectiveness of three different ultrasound techniques for detecting and characterising out-of-plane wrinkles in the typical glass-carbon hybrid laminates that are used for wind-turbine blades. The tests samples were manufactured so that the laminates and the defects are representative of those used in the wind-turbine industry. Basic mechanical tests were performed to check the drop in mechanical properties due to wrinkling. The ideal probe frequency was determined as the resonance frequency of the plies using an analytical ultrasonic-propagation model. The three different ultrasound techniques used are: full-matrix capture (FMC) with the total focusing method (TFM), a commercial phased-array instrument and an immersion test with a raster-scanned single-element focused probe. When possible, severity parameters of the wrinkle were measured on the ultrasonic images and compared with the measurements of the actual sample in order to determine which method best characterises such wrinkles and which would be more appropriate to implement in an industrial environment. Not all of the techniques allowed full characterisation of out-of-plane waviness on the specimens. The FMC/TFM method gave better results whilst phased-array technology and single-element immersion testing presented more challenges. An additional enhancement to the TFM imaging was achieved using an Adapted-TFM method with an angle-dependent velocity correction.