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One of the main characteristics of the maneuverability of power equipment is whether the load may be reduced to the minimum allowable level. The ability of power equipment to operate in a variable regime (with unloading during night time) enables it to participate in the control of frequency and power in the power system. It is important to note that low-load operation of the equipment should not make its performance poorer. In particular, for drum boilers, the required steam conditions and reliable circulation of the working fluid in the evaporation waterwalls should be maintained in the entire operating load range. The numerical-and-experimental studies have substantiated the possibility to reduce the minimum allowable steam load of a typical E-420-13.8-560GM boiler from 210 to 150 t/h. According to the results of thermal design calculations by the Boiler-Designer code, the required steam superheat temperature (560°С) cannot be attained at lower loads. Field tests of an operating boiler have revealed that difficulties with fuel flow control and failures of the furnace's combustion process arise at loads below 150 t/h. Calculations and experimental measurements performed using flow measuring tubes installed in the furnace waterwalls have demonstrated that the fluid circulation of a fluid in the evaporation water walls remains even on a load decrease to 110 t/h. It is pointed out that more than 100 E-420-13.8-560GM boilers, whose design was modified during long-term operation (for more than 40 years), are operating now. Therefore, the minimum steam load should be finalized only after additional studies for each boiler of this type. [ABSTRACT FROM AUTHOR]

This paper aims to solve the problems in the trajectory optimization during the cruise phase that the edge weights are closely related to the selection of the preceding path，and the calculation cost of the evaluation function is too heavy under different objectives like the least fuel consumption，the shortest flight time，and the lowest cost. First，a process is built，involving the GRIB2-format grid meteorological data interpolation and calculation of aircraft performance parameters. Second，the efficiency is augmented by the improvement of the A* algorithm evaluation function coefficient and the step size of performance calculation. Results for typical flight tasks under different optimization objectives are compared and the effects of factors such as cost index，mass of aircraft and flight level are discussed. The A* algorithm that incorporates the flight performance calculation into the edge weights，requires more calculation time than the traditional shortest path algorithm. However，compared with the Dijkstra’s algorithm，it can find the optimal trajectory more quickly under the same performance-based optimization objective. [ABSTRACT FROM AUTHOR]

The article analyses the influence, relationship and value of the design parameters of the thermal flowmeter on its radial and axial heat fluxes in the tube. The purpose of the analyses is to check the change in the error of fuel flow measurement by the thermal flowmeter directly on the vehicle when using heating elements of different diameters. The influence of the radial heat flux of the flowmeter tube on the accuracy of fuel flow measurement is substantiated. Recommendations on the choice of design parameters of a thermal flowmeter at the stage of its design, development or use are developed under the condition of reducing the influence of the radial heat flow on the axial one, which will reduce the total error in the measurement of fuel flow rate. [ABSTRACT FROM AUTHOR]

The article analyses the influence, relationship and value of the design parameters of the thermal flowmeter on its radial and axial heat fluxes in the tube. The purpose of the analyses is to check the change in the error of fuel flow measurement by the thermal flowmeter directly on the vehicle when using heating elements of different diameters. The influence of the radial heat flux of the flowmeter tube on the accuracy of fuel flow measurement is substantiated. Recommendations on the choice of design parameters of a thermal flowmeter at the stage of its design, development or use are developed under the condition of reducing the influence of the radial heat flow on the axial one, which will reduce the total error in the measurement of fuel flow rate.

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The fuel injection ring is an important part of the micro-turbojet engine. The uniformity of fuel injection quantity determines the uniformity of the temperature field in the combustion chamber. Aiming at micro-turbojet injection ring uneven fuel injection problems, the influence of pressure loss is compensated through the use of unequal-diameter needle structure. By using CFX software, the experiment of three-dimensional flow field inside the fuel injection ring is simulated and the outlet flow rate, outlet velocity and the pressure change of the entire internal flow field of injection needle on the injection ring body are calculated and compared with the experimental results. Results show that the scheme of unequal injection nozzle can improve the problem of nonuniform injection of fuel injection ring. According to the calculated results, we can lay the foundation for the study of the internal flow field of the injection ring.

The fuel flow is a key indicator of the performance of aircraft engine. It helps to identify the performance degradation and failure of the engine. This calls for an aircraft engine model that can predict the fuel flow accurately throughout the flight, especially the climb phase. This paper performs stepwise linear regression of the data collected by a quick access recorder (QAR), and creates a model of the fuel flow of Boeing 737-700 in the climb phase. Firstly, the possible influencing factors of fuel flow were screened based on scatterplots and Pearson correlation coefficients (PCCs). Next, the selected factors were further modified and screened through similarity correction and power correction. On this basis, the fuel flow model for the climb phase was established through stepwise linear regression and corrected in the light of the tolerance and variance inflation factor (VIF) of each variable. The prediction results of the final model were basically in line with the actual QAR data. [ABSTRACT FROM AUTHOR]

A statistical analysis has been developed from the ICAO databank to predict aero-engines exhaust emissions during a landing and take-off cycle (LTO). The ICAO databank contains updated emission indices for a vast number of turbojet and turbofan engines only, with thrust ratings greater than 26.7 kN. Correlations are developed and proposed for turboprop and turboshaft engines to overcome the difficulty of assessing exhaust emissions from these engines in absence of industry data. LTO emissions are predicted for a turbofan-powered commuter airplane (Embraer E195) using the surrogate model. It is demonstrated that the predictions are closer to the values extracted from the flight data recorder than to the emissions calculated with the ICAO method. Thus, approximate emissions indices applied to actual flight procedures are a better choice than a standard ICAO LTO emission estimate from the databank. The correlations are then applied to the prediction of LTO emissions of a turboprop airplane (Bombardier Q400). [ABSTRACT FROM AUTHOR]

Operational landing and takeoff standards developed by the International Civil Aviation Organization (ICAO) in the 1970s, have been widely-used in fuel consumption and emissions models or inventory studies. However, these generic standards may cause significant uncertainties due to changes in the air transport system over time and appear to remain highly conservative. To quantify the uncertainty caused by using generic operational standards, in this study, the effects of actual fuel flow and time-in-mode of more than 9000 different domestic flights, performed by five different narrow-bodied aircraft models with seven different engine, on the averages of landing and takeoff fuel burn and emissions are investigated. Compared to the simple approach, suggested by the ICAO, results indicate considerably lower time in mode averages, particularly during taxi-out (42%) and climb (45%) phases, even for high traffic volume airports. The greatest differences in fuel flow are observed during takeoff and approach phases. As a result of using actual time-in-mode and fuel flow data, the actual landing and takeoff fuel burn averages are found to be 35% lower than ICAO values. In addition, the effects of low altitude level flight on approach phase fuel flow, thrust reverser mode on taxi-in phase fuel flow, and stop and acceleration of aircraft on taxi ways on fuel flow are discussed. With regard to emissions, using actual time-in-mode and fuel flow data, landing and takeoff cycle hydrocarbon and carbon monoxide emissions are found to be 34% lower, while nitrogen oxide emissions are found to be 38% lower than those given by the ICAO database. Analyses related to the effects of aircraft mass on emissions indicate that the differences for carbon monoxide and nitrogen oxides between the lightest and heaviest aircraft are 3% and −26%, respectively. The analyses results reveal that uncertainties in landing and takeoff fuel burn and emissions caused by considering ICAO time-in-modes can be significantly higher compared to those caused by considering ICAO fuel flow standards. [ABSTRACT FROM AUTHOR]