Unsteady fluid flow in pressurised closed pipes in experimental bench examples

The paper indicates the frequent occurrence of transient states in hydraulic systems. Particular attention was paid to the phenomenon of water hammer – the causes and effects of this phenomenon. A complete analytical description of this phenomenon has not yet been developed. New theoretical models are still being developed and need to be verified experimentally. The paper focuses on presenting the development of experimental stands for the study of water hammer in hydraulic pipes. Subsequent modifications of the experimental stands for the speed of the shut-off valves and their tightness, as well as for the minimisation of the occurrence of the effects of the pulsation of the performance of the pump supplying the line under investigation, are presented. The stand presented as the final one also allows the testing of transients in hydraulic lines for various types of working fluid (oil, emulsion, distilled water)

Mimośrodowa pompa łopatkowa do transportowania cieczy spożywczych

Historia hydrauliki sięga czasów, w których człowiek zagospodarował ruch cieczy na własne potrzeby. W tamtym czasie nie odwoływano się do zdefiniowanych praw, które obecnie stosuje się w technice hydraulicznej. Pierwsze maszyny wykorzystujące energię cieczy zbudowano już w starożytności, a ponad 200 lat przed naszą erą skonstruowano pompę tłokową ssąco-tłoczącą

Possibilities of effective passive vibration isolation of hydraulic valves

The following paper describes the effect of the introduced vibration isolation on the operation of a hydraulic valve. The method of transmitting the external force to the valve control element and examples of vibration sources are presented. The balance of forces acting on the valve spool and the flow intensity in the tested hydraulic system are determined. The assumptions are simplified and discussed in detail. On their basis, numerical simulations have been carried out and verified by experimental tests. The paper ends with brief conclusions

Preliminary testing of the internal gear pump with modifications of the sickle insert

This paper presents the modifications that have been made to the sickle insert of the gear pump with internal gearing. This procedure allowed the obtainment of radial compensation. The test stand to plot the characteristics of the pump before, as well as after the first and second modification is discussed. The results of the measurements from the tests conducted are presented. The results obtained confirmed the achievement of radial compensation by cutting the appropriate channel in the sickle insert. As a result, it will be possible to obtain a higher discharge pressure for this type of pump and to increase its efficiency

The Concept of Using an Expert System and Multi-Valued Logic Trees to Assess the Energy Consumption of an Electric Car in Selected Driving Cycles

This paper presents the concept of an expert system supporting the decision-making process of rational energy consumption by an electric car. The driving style and the average speed achieved are very important in terms of the driving range. In addition, the influence of ambient temperature on the efficiency of the electric vehicle and ultimately on energy consumption is very important. The proposed system, based on the method of multi-valued logic trees, allows minimizing the objective function, which is aimed at minimizing the energy consumption of an electric car at different ambient temperatures. The generated decisions, directed to the energy management system, can be processed in a variety of temporal and situational dimensions. The application of the system can also provide prompts to the driver on how to adjust the driving style by operating the accelerator and brake pedal. The expert system is an open system, allowing for further generalizations and modifications

Kompensacje promieniowe w pompach o zazębieniu wewnętrznym

Podstawową zaletą pomp zębatych o zazębieniu wewnętrznym w stosunku do pomp o zazębieniu zewnętrznym jest niższa emisja hałasu, mniejszy współczynnik nierównomierności wydajności oraz bardziej zwarta konstrukcja. Wynika to z płynnej współpracy koła o uzębieniu wewnętrznym oraz koła o uzębieniu zewnętrznym. Uszczelnienie w punkcie styku współpracujących kół na zwiększonym obwodzie kół stykających się z przestrzeniami ssawnymi i tłocznymi prowadzi do zmniejszenia strat napełniania podczas zasysania cieczy... [Wprowadzenie

Development tendencies of clearance compensation methods in internal gear pumps

Contemporary gear pumps, although their design has been under development for over four centuries, keep being modernized and improved. The work presents an analysis of design solutions, taking into account their operational features. The analysis included units with internal mesh. Emphasis was put on the problem of ensuring high values of volumetric efficiency by minimizing leakage in the widest possible range of loads while maintaining the highest possible hydraulic and mechanical efficiency of the displacement unit. Increasing the volumetric efficiency of positive displacement pumps is an important factor in the pursuit of increase in working pressures in hydrostatic systems. An important factor in production of pumps is cost of their production, which often leads to possibility of introducing additional modifications in the pump structure. Often changes made to the materials used in construction of pumps, allow reduction in their mass or sensitivity to the action of the transported liquid. The paper indicates the developed and proprietary solutions in this area and presents the results of experimental research

Analysis of the Impact of Vibrations on a Micro-Hydraulic Valve Using a Modified Induction Algorithm

This paper addresses the impact of mechanical vibrations of different frequencies on a particular type of valve. It has been shown that a neural network can be used to compress measurement data and determine the frequency range that is most important in describing the impact of mechanical vibrations on a micro-hydraulic overflow valve. Later, induction decision trees were used for the generated areas, determining key measurement points. The most important areas of dependence are determined using inductive decision trees in induction. The entropy measure is used to determine the most significant attribute. A modified induction algorithm was used for the comprehensive analyses. The analysis carried out in the paper identified the intervals in which the flow rate plays a decisive role for the entire amplitude and frequency spectrum. An analysis was performed for the 200…900 [Hz] frequency interval of the external driving force, with a harmonic step of 10 [Hz]. The analysis was performed while considering these main valve parameters: the pressure of the overflow valve opening p = 10 [MPa]; flow rate in the valve: 0.6, 0.8 and 1 [dm3/min]; stiffness of valve spring c = 7.49 [N/mm]. Plots were presented and for each plot, the most important four intervals were determined. They are hierarchically ordered in the interval range of the whole frequency spectrum range: (coefficient IV)—the most important; (coefficient III)—important; (coefficient II)—less important; (coefficient I)—least important. A test rig and the results of a study on the effect of mechanical vibration on changes in the amplitude-frequency spectrum of pressure pulsations of a micro-hydraulic system, in which a micro-hydraulic relief valve was subjected to mechanical vibration, are presented

Analysis of the Impact of Vibrations on a Micro-Hydraulic Valve Using a Modified Induction Algorithm

This paper addresses the impact of mechanical vibrations of different frequencies on a particular type of valve. It has been shown that a neural network can be used to compress measurement data and determine the frequency range that is most important in describing the impact of mechanical vibrations on a micro-hydraulic overflow valve. Later, induction decision trees were used for the generated areas, determining key measurement points. The most important areas of dependence are determined using inductive decision trees in induction. The entropy measure is used to determine the most significant attribute. A modified induction algorithm was used for the comprehensive analyses. The analysis carried out in the paper identified the intervals in which the flow rate plays a decisive role for the entire amplitude and frequency spectrum. An analysis was performed for the 200…900 [Hz] frequency interval of the external driving force, with a harmonic step of 10 [Hz]. The analysis was performed while considering these main valve parameters: the pressure of the overflow valve opening p = 10 [MPa]; flow rate in the valve: 0.6, 0.8 and 1 [dm3/min]; stiffness of valve spring c = 7.49 [N/mm]. Plots were presented and for each plot, the most important four intervals were determined. They are hierarchically ordered in the interval range of the whole frequency spectrum range: (coefficient IV)—the most important; (coefficient III)—important; (coefficient II)—less important; (coefficient I)—least important. A test rig and the results of a study on the effect of mechanical vibration on changes in the amplitude-frequency spectrum of pressure pulsations of a micro-hydraulic system, in which a micro-hydraulic relief valve was subjected to mechanical vibration, are presented

A novel design of a low-pressure composite vessel with inspection opening – design, manufacturing and testing

Composite structures, especially pressure vessels, pipelines, and additional components such as tees, reductions, or inspection openings are more and more willingly used in the chemical industry. In this research, a novel design of a low-pressure composite vessel with an inspection opening is presented. The vessels are unsymmetrical considering the domes. On one side the opening is considerably bigger, around half of the cylindrical diameter of the vessel. This design requires a new approach to manufacturing such structures. In this study, a two-step analysis was performed. Firstly, small-size pressure vessels (S) were manufactured and the design of dome reinforcement was validated. Then, the final design of vessel (M) was produced, with a volume of around 700 litres. The vessels were initially calculated for 21 bars of burst pressure. During burst pressure tests, the strains were measured with optical fibres (FBG) and strain gauges. Additionally, the acoustic emission was utilized to predict the damage modes and locations. Finally, a microscopic evaluation of the specific parts of the vessels was performed. Conclusions were drawn, that the proposed novel design of dome reinforcement around the inspection opening fulfilled the strength and stiffness requirements