Ingeniería Agrícola y Biosistemas Volume 10, issue 1, Enero - Junio 2018 Electronic ISSN: 2007-4026
Print ISSN: 2007-3925
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Ingeniería Agrícola y Biosistemas
Volume 10, issue 1, Enero - Junio 2018
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Determination of shear velocity in a mild-sloping open channel flow Scientific article

Determinación de la velocidad de corte en un flujo de canal abierto de baja pendiente

Ángel Mendoza-González; Ariosto Aguilar-Chávez

http://dx.doi.org/10.5154/r.inagbi.2017.01.002

Received: 2017-01-24

Accepted: 2017-11-25

Available online: 2018-02-13 / pages 03-12

  • Objective: To present a methodology that allows experimentally determining shear velocity, considering the log-law as a model of velocity distribution in the outer region of turbulent flow. 
    Methodology: The experimental study was carried out in a rectangular-shaped, variablysloped channel with a 0.245-m-wide base and 5 m long. Flow velocity was measured with an Acoustic Doppler Velocimeter (ADV), and the measurement area was 12 mm. Shear velocity was determined by the instantaneous velocity equation (ui,j). 
    Results: The log-law model had a good statistical fit with the shear velocity estimated from the experimental data.
    Study limitations: The experimental tests were conducted only in subcritical regime with low aspect ratios. In addition, in all tests, the measurement of instantaneous velocities was carried out only in a 12-mm profile, as close as possible to the wall.
    Originality: The model to calculate the shear velocity is presented explicitly, and the statistical approach employed supports the use of the median as an estimator of the shear velocity.
    Conclusions: The presented methodology shows low uncertainty in the estimation of shear velocity. The Anderson-Darling test showed that the results do not follow a normal distribution, so the median is the statistical parameter to define the shear velocity value.

Classical thermodynamic-based models for predicting physical properties of a biodiesel fuel Scientific article

Modelos basados en termodinámica clásica para predecir las propiedades de biodiésel

José E. Benavides-Fajardo; Mauricio Romero-Bastida; Felipe A. Perdomo; Ma. Del Carmen Núñez-Santiago

http://dx.doi.org/10.5154/r.inagbi.2017.10.014

Received: 2017-10-23

Accepted: 2018-0202

Available online: 2018-06-27 / pages 13-32

  • Objective: To obtain a model based on the classical Peng-Robinson equation of state (PR-EOS) to evaluate the initial thermodynamic expressions (first- and second-derivative properties) in biodiesel.
    Methodology: A modified temperature dependence was used to transform the volume of the Peng-Robinson cubic equation of state to predict the thermophysical properties of biodiesel. The fuel studied is composed of five fatty acid methyl esters (methyl palmitate, stearate, oleate, linoleate and linolenate), which are the primary constituents of biodiesel.
    Results: The results showed that the approach presented in this work can improve the prediction of secondorder properties (isentropic bulk modulus, heat capacities and speed of sound) if the accuracy of the primary properties is maintained (vapor pressure and liquid density).
    Study limitations: Biodiesel is highly corrosive and is used in mixtures with other fuels such as gasoline; however, the model is only applicable to the properties of biodiesel and not mixtures.
    Originality: Two concepts in the Peng-Robinson equation are used: the α(T) function and volume transformation. The second concept was implemented because second-order thermodynamic properties need accurate densities and derivatives with respect to the total volume. Additionally, the α(T) function was selected through a systematic search among a wide range of reported correlations.
    Conclusions: The proposed thermodynamic model can predict, with only a few experimental data, properties that have an impact on the representation of spray, atomization and combustion events in diesel engines.

Kinematic wave hydrologic model of the Turbio River basin, Guanajuato, Mexico Scientific article

Modelo hidrológico de onda cinemática de la cuenca del río Turbio, Guanajuato, México

Gregorio Vargas-Castañeda; Laura A. Ibáñez-Castillo; Ramón Arteaga-Ramírez; Gustavo Arévalo-Galarza

http://dx.doi.org/10.5154/r.inagbi.2017.07.012

Received: 2017-07-28

Accepted: 2018-04-19

Available online: 2018-06-27 / pages 33-47

  • Objective: To apply the HEC-HMS methodology based on kinematic wave theory in the Turbio river basin to increase the accuracy of the model in predicting storm runoff.
    Methodology: Calculations were made for: 1) rainfall depth to runoff depth, through the Soil Conservation Service (SCS) runoff curve number method, 2) runoff depth to hydrograph, for which the SCS unit hydrograph method and kinematic wave (KW) method were used, 3) flood routing in channels, by the Muskingum and KW methods, and 4) flood routing in dams, with the mass balance method. All steps were executed with the HEC-HMS program. Combinations and comparisons of methods 2 and 3 were made, while 1 and 4 remained constant.
    Results: The hydrologic model that presented the highest Nash-Sutcliffe efficiency index (NSE) was the KW-Muskingum combination, where the runoff depth becomes a hydrograph through the KW and the flood routing in channels is carried out with the Muskingum method, and the lowest value was shown by the KW-KW combination.
    Study limitations: The models were calibrated for only one event, due to the simultaneous availability of sub-hourly rainfall and flows. This limitation implies that subsequent efforts should focus on validating the kinematic wave model.
    Originality: The hydrologic model presented here is by events and could be implemented in a flood early warning system.
    Conclusions: According to the NSE, the three methods were satisfactory; however, the best was the KW-Muskingum combination.

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