Aviation

Aircraft hydraulic drive energy losses and operation delay associated with the pipeline and fitting connections

Mykola Karpenko — 2024-02-28

Theoretical research on hydraulic processes occurring in aircraft hydraulic drives is presented in the studies. Installation of angular fitting connections in aircraft pipeline systems influences hydrodynamic processes and fluid flow characteristics analysed in the research. The provided analysis is based on a validated numerical model utilizing Navier–Stokes equations and the k-epsilon turbulence model. Fluid flow inside the aircraft hydraulic drive pipeline system was investigated with flow rates up to 100 l/min. A mesh independence study was conducted for numerical simulation of the fluid flow. The obtained results include fluid pressure drops, energy losses, and operational delays associated with fluid flow vortex formations at 45° and 90° angular fitting connections. Additionally, compared results from standard methods of calculation for angular fitting connections, including the equivalent length and equivalent length same shape methods.

A mathematical model for identifying military training flights

Anna Borucka — 2024-02-28

The main tasks of the Training Air Base concern the practical training of cadets in piloting techniques as well as maintaining and improving the piloting skills of the instructors. It is essential to maintain the infrastructure of the airfield and the Base as a whole ready for operation. This allows for fulfilling the fundamental mission of such military units, which is to provide effective operations for the defence of the state. Therefore, measures to support and improve the operation of such military facilities are extremely important and also became the genesis of this article. It analyses and evaluates the number of flights carried out over seven years (2016–2022) at the studied training base using mathematical modelling, allowing to assess the variability of the studied series. The phase trends method was used for this purpose, preceded by a seasonality study. It allowed the identification of periods in which the number of flights performed varies significantly. Such knowledge enables better regulation of the airport’s operation, adjustment of activities to the needs, and the determination of further directions for airport development and the justification of potential investments. An additional value of the article is the presentation of a mathematical modelling method specifically designed for seasonal time series, along with their diagnostics. It also provides an opportunity for other institutions to carry out tasks while upholding the highest standards.

Exploring the possibilities of using bio-additives in military aviation fuels

Jacek Ryczyński — 2024-03-04

Analyzing the research directions of leading aviation companies, it is evident that biocomponents will soon become a very important addition to the fuel used in turbine aircraft engines. Similarly, intensive efforts are underway to implement this type of solution in the armed forces. Here, the situation is more complex. All military fuels are intended for long-term storage, and bio-additives significantly alter the properties of fuels during this specific storage process. These changes invariably result in the deterioration of fuel quality parameters. The article presents an analysis and conclusions related to biocomponents as additives to F-35 fuel (NATO code-the military equivalent of Jet A-1 fuel). F-35 aviation fuel mixtures with the addition of biocomponents (HVO-Hydrorefined Vegetable Oil) at concentrations of 0–20% (V/V) were independently composed and stored for extended periods (0–6 months). The disadvantages and potential problems of this solution are discussed. The research has demonstrated that using biocomponents in the mixtures significantly alters the course of the distillation curve and increases the fuel’s electrical conductivity. Another adverse effect observed was a significant deterioration in the fuel’s low-temperature properties. The research indicates that using a bio-additive like HVO in F-35 fuel will require addressing many challenges. At the level of laboratory tests, it is to determine the limit value of the share of a biocomponent in a mixture at which the normative values are not yet violated and to confirm or rule out whether the mixtures are suitable for long-term storage.

International competitiveness and recovery strategy of the aviation and space industry of Ukraine

Olha Karpiak — 2024-03-14

The influence of the aviation and space industries on the development of the world economy and economic development, industrial potential, competitiveness and position of various countries in the world is shown in the article. Global aviation and space market has been studied and an economic analysis of the aviation and space sector of the industry of the countries that are among ten world leaders in the industry was carried out. The main indicators of the development of the aviation and space industry of world countries-leaders and Ukraine have been systematized. The volumes of income of the leading companies of the industry producers, between which there is fierce competition, have been given. International competitiveness has been analyzed and ways of recovery and development of the aviation and space sector of Ukraine were proposed, taking into consideration the significant losses and damages caused by full-scale military invasion of aggressive neighbor on the territory of Ukraine. Scenarios of competitive behavior were considered and a strategy for the restoration of one of the largest enterprises in the world and single one in the aviation and space industry in Ukraine that has completed the cycle of engine production – Joint Stock Company Motor Sich has been made.

Modification of the sickle insert of an internal gear pump

Krzysztof Towarnicki — 2024-03-19

The reduction of the weight of high-pressure components and systems (including hydraulic) is especially important in aircraft or mobile machinery. An interesting trend that began in the first half of the 20th century in the aviation industry is the weight reduction of structures by using components made of composite materials in place of those made of conventional materials. This trend is not only not diminishing, but is actually increasing year by year. This paper investigates the effect of modifying the design of the sickle insert on the volumetric efficiency of the pump. Moreover, this work presents the replacement of the sickle insert of an internal gear pump made of bronze with plastic materials, reducing its weight by 80%. To ensure similar performance, its design was modified, increasing the pump’s efficiency while additionally reducing its weight. This material substitution allows the reduction of weight, but it can adversely affect the performance of the hydraulic component, this also applies to the displacement pumps. For this reason, the design had to be changed to obtain similar operational parameters after changing the material.

The impact of mechanical vibrations on hydraulic valves and the possibility of reducing the effects

Michał Stosiak — 2024-03-28

The paper shows that mechanical vibrations occur in a wide frequency range in the hydraulic systems operating in the real world. Hydraulic valves are also exposed to these vibrations. The paper gives examples of vibration sources and suggests that the influence of vibrations on hydraulic valves could be reduced. Particular attention was paid to the vibrating proportional distributor. The amplitude-frequency spectrum of pressure pulsation in a hydraulic system with a vibrating proportional distributor was analysed. During the tests, the frequency of external mechanical vibrations acting on the proportional distributor and their direction was changed.