Fuel savings are a significant aspect for evaluating the current and future technologies of civil aviation. Continuous-Descent Approach (CDA), as a representative of new concepts, requires a method for evaluating its fuel benefits. However, because of unavailability of the practical operational data, it is difficult to validate whether the previous fuel consumption mechanisms are suitable. This paper presents a unique method for quantifying potential fuel benefits. This permits an easy evaluation for the new procedures without modelling before implementing field tests. The proposed method is detailed in this paper. It derives from the inherent mechanical characteristic of aircraft engine, and utilizes historical flight data, rather than modelling, to predict fuel flow rates by matching flight conditions from Quick Access Recorder (QAR) data. The result has been shown to predict fuel consumption for conventional descent with the deviation of ±0.73%. To validate such method, a case study for our designed CDA procedure is presented. Fuel consumptions in baseline scenarios are estimated to analyse the variable impacts on fuel consumption. The estimated fuel benefits are consistent with the results in the previous field tests. This analysis helps support Air Traffic Management decisions on eventual field test by reducing the validation time and cost.
Four-dimensional (4D) trajectory is considered to be one of the effective means to reduce the environmental impact of aviation while increasing capacity and safety. This paper proposes an approach to optimize cruise speed profile subject to wind uncertainty, aiming to reduce the fuel burn complying with the Required Time of Arrival (RTA) constraints. The approach is based on a probabilistic framework, and the uncertainty propagation is analyzed using a Probability Transformation Method, and the probability distributions of arrival time and fuel consumption are determined. In addition, from an airborne operation perspective, transition profiles need to be considered in the reference speed optimization problem, aiming to improve the rationale of the reference trajectory. Numerical simulations are presented, and the results demonstrate that the speed profiles optimized by this method are able to meet the RTA constraints in the presence of wind uncertainty, with an average reduction of 7.04% in fuel consumption compared with that of the flight data.
As an important subsystem in air-conditioning system, water system connects the chiller and terminal equipment. Therefore, it is necessary to develop an accurate thermal model for chilled water pipe to create the suitable indoor temperature and humidity environment. In this paper, the thermal model of the pipe was considered by utilizing the simplified thermal time-delay state-space model with the mass, energy balance, and heat consumption equations. Based on this improved model, the preview control as control strategy for water pipe temperature was proposed, and its robustness and stability were discussed. Subsequently, the performances of this model and control strategy were tested in a fan-coil system simulating with MATLAB and TRNSYS (Transient System Simulation Program). Explicitly, the results show that this model accurately predicts the thermal characteristic, and the average mean squared errors for water temperature were 11.14% and 12.82%, respectively. Meanwhile, the tracking effect of valve controller was better than the control strategy with no preview control.
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