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Effect of nozzle rotation angles and sizes on thermal characteristic of swirl anti-icing
Mohd Azmi Ismail,Jian Wang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.9
The Federal Aviation Administration requires all aircraft manufacturers to adhere to maximum noise level standards. Thus, a bias acoustic liner is introduced, to intensify the noise equipment system, as well as prevent ice accumulation on the nacelle D-chamber. The hotspot phenomenon, by the Piccolo tube anti-icing system, could damage the bias acoustic liner. Therefore, a swirl anti-icing system is further investigated, to reduce the hotspot effect on the bias acoustic liner. The present work investigates the effect of nozzle rotation angles at various mass-flow-rates of hot-air supplied on the nacelle lip-skin temperature distribution, in order to enhance the swirl antiicing system's performance. The effect of the nozzle ratio area on the swirl anti-icing system's performance to be discussed in the present work. The simulation results show that the hotspot temperature decreases by 26 % and the cold spot temperature increases by 18 %, as the nozzle to be rotated from 0 o to 13 o towards the inner skin. However, the nozzle ratio area shows a negative effect on the swirl antiicing performance, where the hotspot temperature increases by 6.7 % and the cold spot temperature decreases by 30.2 % with the ratio nozzle area increasing from 0.1083 to 0.8354. According to swirl anti-icing empirical values, the average Nusselt number is directly proportional to the average Reynolds number. In conclusion, the temperature distribution on the nacelle lip-skin and the swirl anti-icing system's performance improves as the angle of nozzle direction increases, rotating towards the inner skin. Swirl anti-icing does not generate hotspot on the inner skin, thus making it suitable for use in a bias acoustic liner system.
Experimental study on aerodynamic performance of nacelle lip-skin bias flow
Lee Chern Khai,Mohd Azmi Ismail,Qummare Azam,Nurul Musfirah Mazlan 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.4
The drag coefficient of the nacelle lip-skin model was investigated to analyze the aerodynamic performance of the bias acoustic liner underneath the nacelle lip-skin at lowspeed free stream velocities. Drag coefficient reduction, using the bias flow of a bias acoustic liner on a nacelle lip-skin, is discussed for incompressible flow condition. The experimental data were recorded to analyze the nacelle lip-skin's drag coefficients. The investigation covered four different bias flow areas to total nacelle lip-skin area ratios, ranging from 0 % to 12 %, at Reynolds numbers ranging from 2.2x10 5 to 3.5x10 5 and the nacelle internal static pressure of 0-90 Pa, with the uncertainty of the experimental data being less than 10 %. The results show that the drag coefficient is reduced by up to 19 % as the ratio of the bias flow area to the total nacelle lip-skin area increases from 0 % to 12 %. In the transition flow regime, the drag coefficient increases gradually with Reynolds number. In addition, the optimum nacelle internal static pressure of present study was found to be 60 Pa.
Ambok Bolong Abol-Munafi,Bui Minh Tam,Mohd Azmi Ambak,Patimah Ismail 한국통합생물학회 2004 Animal cells and systems Vol.8 No.4
A study was conducted to determine growth and survival rates of snakehead (Channa striata) larvae. Live foods such as Artemia salina nauplii, Moina micrura and bloodworm and artificial diet were given to larvae from 1-15 days after hatching as the 1st phase and from 15-30 days as the 2nd phase. In the 1st phase, the growth and survival rates of larvae fed with Artemia nauplii were significantly different from larvae fed with Moina (p < 0.05) with values of 28.5 mg, 49% and 26.7 mg, 31%, respectively. Meanwhile, all larvae fed with bloodworm (Chironomus sp.) or artificial diet (49% protein) died within 10 days of experiment. For the 2nd phase, growth of the fry fed with Artemia or Moina differed significantly from that fed with bloodworm or pellet (200.1, 187.7, 109.6 and 8.2 mg, respectively). Specific growth rate (SGR) of larvae fed with Moina was higher than that of larvae fed with Artemia (17.9 and 17.4% day -1, respectively) in the 1st phase. In the 2nd phase, SGRs of larvae fed with Artemia (12.7% day -1) or Moina (11.5% day-1) were significantly higher than those of larvae fed with bloodworm (8.3% day-1) or dry diet (6.1% day-1). Generally, Artemia and Moina were suitable food for snakehead larvae during the first month of their life, and artificial diet was much less acceptable and resulted in poor growth and survival.
Ambok, Bolong,Abol, Munafi,Bui Minh, Tam,Mohd Azmi, Ambak,Patimah, Ismail The Korean Society for Integrative Biology 2004 Korean journal of biological sciences Vol.8 No.4
A study was conducted to determine growth and survival rates of snakehead (Channa striata) larvae. Live foods such as Artemia salina nauplii, Moina micrura and bloodworm and artificial diet were given to larvae from 1-15 days after hatching as the 1st phase and from 15-30 days as the 2nd phase. In the 1st phase, the growth and survival rates of larvae fed with Artemia nauplii were significantly different from larvae fed with Moina (p < 0.05) with values of 28.5 mg, 49% and 26.7 mg, 31%, respectively. Meanwhile, all larvae fed with bloodworm (Chironomus sp.) or artificial diet (49% protein) died within 10 days of experiment. For the 2nd phase, growth of the fry fed with Artemia or Moina differed significantly from that fed with bloodworm or pellet (200.1, 187.7, 109.6 and 8.2 mg, respectively). Specific growth rate (SGR) of larvae fed with Moina was higher than that of larvae fed with Artemia (17.9 and 17.4% day$^{-1}$, respectively) in the 1st phase. In the 2nd phase, SGRs of larvae fed with Artemia (12.7% day$^{-1}$) or Moina (11.5% day$^{-1}$) were significantly higher than those of larvae fed with bloodworm (8.3% day$^{-1}$) or dry diet (6.1% day$^{-1}$). Generally, Artemia and Moina were suitable food for snakehead larvae during the first month of their life, and artificial diet was much less acceptable and resulted in poor growth and survival.
Developing flow of Newtonian fluids over superhydrophobic transverse grooves in circular tube
Kok Hwa Yu,Han Wei Lee,Yew Heng Teoh,Mohd Azmi Ismail 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.1
In this paper, the effects of dimensionless gas area fraction ( δ ) and normalized groove-rib periodic spacing ( Λ ) on developing flow for Newtonian fluid past circular tube having alternating superhydrophobic transverse grooves were numerically investigated. Fluid flow at Re ranging from 0.001 to 10 over various superhydrophobic microstructures scales ( 0.05 < Λ < 1, 0 < δ < 1 ) were studied. Numerical results show that the presence of superhydrophobic transverse grooves would consistently yield a longer hydrodynamic entrance length ( ) h L as compared to that of smooth surface. This is principally owing to the flow redistribution with higher flow rate that is permitted in the vicinity of the superhydrophobic wall. However, the scale of the superhydrophobic transverse grooves yield non-monotonic trend on hydrodynamic entrance length, with reduced delaying effect at higher Λ . Despite the h L alteration, h L arising from the presence of superhydrophobic transverse grooves in tube of diameter D , at low Re (i.e., Re < 1 ), is still bounded within tube length of D .