Підвищення паливної ефективності літа ка є однією із основних вимог, які висувають ся до перспективних літальних апаратів та літальних апаратів, які модернізуються. Проведено оцінку зміни аеродинамічної якос ті і, як наслідок, підвищення паливної ефек тивності дальнього магістрального літака при застосуванні перспективних засобів під вищення аеродинамічної якості. До зазначе них засобів відносяться: відмова від меха нізації кромок крила та від традиційних органів керування шляхом застосування адаптивного крила, штучна ламінарізація течії навколо елементів планеру, застосу вання кінцевих аеродинамічних поверхонь. Відмова від традиційних органів керуван ня та механізації крила зумовлена необхід ністю забезпечення безшовної поверхні еле ментів планера для запобігання передчасної турбулізації течії і, як наслідок, призво дить до зменшення профільного опору літа ка. Застосування кінцевих аеродинамічних поверхонь направлене на зниження індук тивного опору. Визначення зміни паливної ефективності літака дозволить оцінити зміну його експлуатаційних витрат протя гом життєвого циклу. Дослідження проведено на основі відомо го модульного програмного комплексу «Інте грація 2.1». Інженерноштурманський роз рахунок виконувався для типового профілю польоту дальнього магістрального літака. Показана можливість зменшення витрати палива до 20 %. Найбільший вплив на зменшен ня витрати палива має ламінарізація течії на поверхні елементів планеру, при цьому зменшення витрати палива склало 17,1 %. Відмова від механізації та елеронів забезпе чила зменшення витрати палива на 3,9 %, при цьому відмова від елеронів, передкрилка та закрилка забезпечило зменшення витра ти палива на 0,4, 1,5 та 0,4 відсотків від повідно. Застосування спіроідних кінцевих аеродинамічних поверхонь забезпечило змен шення витрати палива на 1,95 % Ключові слова: аеродинамічна якість, паливна ефективність, адаптивне крило, штучна ламінарізація, спіроідні кінцеві аеро динамічні поверхні UDC 629.7.
This paper reports a modernization concept of aircraft An-26 and An-140 based on the use of a hybrid basic propulsion system (HBPS). The study object is the aircraft of transport and passenger categories in the weight dimension from 20 to 25 tons. The analysis of the ways of modernization has shown that under the new market conditions two directions in the development of light aircraft «Antonov» become relevant. The first is the modernization of the existing fleet of An-26, the second is the construction of an An-140T ramp transport variant based on the An-140 aircraft. One of the considered ways of such modernization is to equip the aircraft with hybrid basic propulsion systems consisting of the gas-turbine and power electric motors, which drive the rotation of the propeller. The use of HBPS makes it possible to optimize the operation of the gas-turbine engine over a narrow traction-speed range -only for the cruising section of the flight. This makes it possible to design a GTE with high fuel and weight efficiency. In this case, noise and harmful emissions could be significantly lower. The analysis has been given of existing aviation hybrid propulsion systems with recommendations on the choice of the optimal scheme to modernize aircraft An-26 and An-140. It is proposed to solve the task by choosing the option of a basic propulsion system with a moderate degree of hybridization, based on the well-established engine TV3-117VMA-SBM1.That improves the flight range of An-26 and An-140 with a payload capacity of 4.5-5 tons by 1.4-1.7 times, respectively. The results obtained confirm the correctness of the proposed modernization concept. The analysis results demonstrate a significant improvement in the flight characteristics of the aircraft, as well as compliance with current and projected environmental standards. The results reported could be recommended for the practical modernization of aircraft An-26 and An-140
Self-oscillations are one of the common problems in the complex automatic system, that can occur due to the features of the workflow and the design of the governor. The development of digital control systems has made it possible to damp self-oscillations by applying complex control laws. However, for hydromechanical systems, such way is unacceptable due to the design complexity and the governor cost. The objective of this work is to determine the parameters of the hydromechanical free turbine speed controller, ensuring the absence of self-oscillations during ground tests of the turboshaft engine with a hydraulic dynamometer. The TV3-117VM engine (Ukraine) with the NR-3VM regulator pump (Ukraine) was selected as the object of the study. However, self-oscillations can also occur in any modifications of the TV3-117 engine with any NR-3 regulator pump. The results of the research may be of interest to engineers and scientists who investigate the dynamics of automatic control systems for similar engines. The paper analyses the nonlinear features of the empirical characteristics of the FTSC leading to self-oscillations of the engine speed. The authors propose the mathematical model of the automatic control system dynamics, which takes into account all the features of the engine and regulator pump. It is shown that the load characteristics of the water brake and the helicopter main rotor can differ significantly. Research of the dynamic characteristics of the TV3-117VM engine was carried out. The analysis showed a good agreement between the calculation results and the field test results, and made it possible to determine the parameters of the controller, which lead to self-oscillations during test. Two cases are considered. The first case includes ground tests of the engine with a water brake; the second case—flight tests of the engine as part of the helicopter’s power plant. The data obtained make it possible to develop recommendations for adjusting the hydromechanical governor without testing it on the engine.
Spiroid wingtip devices (WD) offer a promising way of improving the lift drag ratio of UAVs, but may on the other hand lead to negative aerodynamic interference of the wing with the WD and deterioration of the aerodynamic characteristics as compared to a wing without the WD. Determining the influence of the geometric parameters of a spiroid WD on aerodynamic wing characteristics, however, remains an understudied field. In our study, we investigated the influence of the following geometrical parameters on wing aerodynamic characteristics with WD: area, radius, camber angle, constriction, and pitch of the spiroid. We found that the positive effect of the WD is present at a relative radius > 0.05, as well as with an increase in the lift coefficient C L as a result of an increase in the proportion of inductive resistance. For example, with the Reynolds number Re = 2.1×105 for a rectangular wing with an aspect ratio θ = 5.12 equipped with a spiroid WD with =0.15 the quality gain is almost 10% at C L = 0.5, and at C L = 0.7 is almost 20% and at C L = 0.7 – almost 20% compared to a wing without WD. Moreover, we found that a change in the camber angle WD θ provides an increase in the derivative of the lift coefficient with respect to the angle of attack in the range from θ = 0° to θ = 130°. By changing the camber angle, it is possible to increase the lift drag ratio of the layout up to 7.5% at θ = 90° compared to θ = 0° at the Reynolds number Re = 2.1×105. From the point of view of ensuring maximum lift drag ratio and minimum inductive drag, the angle θ = 90° is the most beneficial.
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