Otonom temizlik aracına ait emiş sisteminin tasarımı ve prototip imalatı = Design and prototype manufacturing of the suction system of the autonomous cleaning vehicle

Abstract

Fanlar, motordan elde ettikleri enerjiyi fan içerisinde bulunan akışa aktaran turbomakinelerdir. Toz, parçaçık ve partikul bulunduran akışının taşınması, iklimlendirme, soğutma ve havanlandırma vb. pek çok sektörde kullanılmaktadır. Yüksek debi ve basınç gerektiren durumlar için en büyük tercih sebebidir. Fanlar birçok başlık altında sınıflandırılmıştır. Temel olarak fanlar akışın giriş ve çıkış yönüne göre radyal (santrifüj) ve eksenel fan olmak üzere iki temel başlıkta sınıflandırılmıştır. Eksenel fanlarda akış kanata eksenel olarak girer ve çıkar. Radyal fanlarda ise akış kanata girişi ve çıkışı arasında 90°'lik açı vardır. Radyal fanlar birçok parçadan oluşmak üzere rotor ve salyangoz olmak üzere iki ana parçadan oluşmaktadır. Rotor, fanın eksenel olarak hareket eden elemanı olup akışı bir ortamdan basınçlandırarak istenilen ortama istenen basınç ve debi değerlerinde iletilmesini sağlamaktadır. Salyangoz, rotor kanatlarından çıkan akışın toplanması ve istenilen konuma yönlendirilmesi sağlamaktadır. Tez kapmasında otonom temizlik aracına ait emiş sisteminin tasarımı, simülasyonu ve prototip yapılmıştır. Otonom temizlik aracında hedeflenen fan debi değeri 186 m3/h'tir. Yüksek verim ve yüksek basınç ihtiyacından dolayı otonom temizlik aracının emiş sisteminde geriye eğik kanatlı radyal fan türü tercih edilmiştir. Radyal fan tasarımı için teorik sonuçlar yardımıyla Solidworks programını kullanılarak CAD dosyaları elde edilmiştir. Analiz için Ansys programı içerisinde bulunan Fluent programı yardımıyla HAD analiz çalışmaları yapılmıştır. Analiz aşamasında optimum sonuçların elde edilebilmesi için radyal fan geometrisi üzerinde bazı parametreler değiştirilerek analizler aynı sınır şartlarında tekrarlanmıştır. Tasarım güncellemeleri radyal fanın kanat parametrelerinden biri olan kanat açısı değiştirilerek simülasyon çalışmaları yapılmıştır. Radyal fanın kanat giriş açısı olan β1 parametresi sabit tutularak kanat çıkış açısı olan β2 parameteresi değiştirildikten sonra β2 paremetesi sabit tutulup β1 parametresi değiştirilerek elde edilen veriler karşılaştırılmıştır. Daha sonra radyal fanın farklı kanat açı durumuna göre farklı kanat sayılarında değişiklikler yapılarak hız ve basınç değerleri incelenmiştir. Fanın kanat yapısında gerçekleştirilecek değişimlerle kanat açısı ve debi farkını da dikkate alınarak basınç farkının arttırılması amacıyla emişin istenilen seviyeye ulaşabileceği nihai fan tasarımı elde edilmiştir. Elde edilen verilere göre deneysel çalışmalar yapılarak fan performans parametreleri elde edilmiştir.

Fans are turbomachines that transfer the energy they obtain from the engine to the flow in the fan. Transport of dust, particles and particulates, air conditioning, cooling, and ventilation, etc. used in many industries. It is the most preferred reason for situations requiring high flow and pressure. Fans are classified under many headings. Classification has been made according to the angle difference between the inlet and outlet of the air in the fans according to the trajectory of the air. Accordingly, the fans are named as axial fans, radial fans, cross flow fans and reciprocating flow fans. According to the draft of the air, the fans are classified according to the transmission of the flow to a larger volume area. They are named as suction fans, discharge fans, suction, and discharge fans. According to the relative pressure increase in the air, the purpose of the fans is to provide flow transmission by creating a pressure difference. They are classified as low-pressure fans, medium pressure fans and high-pressure fans. Basically, according to the trajectory of the air, the fans are classified under two main headings as radial (centrifugal) and axial fans according to the inlet and outlet axis of the flow. In axial fans, the flow enters and exits the blade axially. In radial fans, there is a 90° angle between the inlet and outlet of the flow blade. Radial fans consist of two main parts, rotor and volute. The rotor is the axially moving element of the fan, and it pressurizes the flow from a medium and ensures that it is transmitted to the desired medium at the desired pressure and flow rates. The volute ensures that the flow coming out of the rotor blades is collected and directed to the desired location. Radial fans are examined under four headings. These are forward curved blade radial fans, radial blade radial fans, backward curved blade radial fans and airfoil radial fans. Radial fans with forward curved blades are called Sirocco fans and their blade outlet angle is greater than 90°. It is preferred for medium efficiency and low cycle requirements. The rotor rotates in the same direction as the blade direction. The blade angle of radial bladed radial fans is 90° and is used for high speed and pressure requirements. It is preferred for needs such as dirty air transport, oil and particle transmission. The blade outlet angle of radial fans with backward curved blades is less than 90° and is used for high flow, pressure and efficiency needs. The blade direction and rotor rotation direction are opposite. Airfoil radial fans have a blade angle of less than 90° like radial with backward curved blades and are preferred for high flow and pressure requirements. Since it is difficult to manufacture compared to other radial fans, it is produced according to special needs. Since there is a rotor as a rotating element in radial fans, it is classified as a turbomachinery. In order to carry out theoretical calculations of turbomachines, it is necessary to assume that there are an infinite number of blades and that the blade thicknesses are infinitely small. By making these assumptions, Euler turbomachinery equations can be used. Due to the three-dimensional flow in the fan, unpredictable movements occur in the fans. Losses occur due to the pressure difference between the two faces of the fan blades. These losses are examined under four headings. Friction losses are diffuser losses, Eddy losses and shock losses. Friction losses, the formation of viscous drag in the air as the rotor moves, is called friction loss. Diffuser losses cause energy loss in the flow by widening the distance between the blades with the movement of air in the fan. Eddy losses are different because the pressure values on the front and back of the fan blades are not the same. This speed difference causes Eddy loss since it does not create similar flow motion. Shock losses occur at the interface with sudden pressure changes. The interface causes shock losses. Calculations should be made by taking these losses into account while making theoretical calculations. There are different variants of the rotor and volute in the design of the suction system. Rotor parameters are blade inner diameter, blade outer diameter, blade thickness, blade radius, blade entry angle and blade exit angle. The blade inner diameter is calculated with the help of total flow, Pfleiderer flow number and Cs values. The wing outer diameter is calculated with the help of head, flow, efficiency and pressure coefficient, which is a dimensionless number. Wing thickness is calculated with the help of average meridian velocity. The wing radius is calculated with the help of a constant equation from the data obtained. The blade entry angle is calculated from the mean meridian velocity and the entry circumferential velocity. Blade outlet angle is calculated with the help of blade number, blade inner and outer diameter. The snail parameters are virole angle, tongue position angle, tongue radius and snail thickness. Virole angle is calculated by a fixed equation with the help of the virole radius and the constant K. The tongue position angle is calculated with the help of the obtained constant equation. The snail thickness is calculated with the help of the meridian velocity and the flow velocity at the impeller exit. In this thesis, the changes on some of the rotor parameters were examined. In the thesis, the design, simulation, and prototype of the suction system of the autonomous cleaning vehicle were made. The targeted fan flow rate in the autonomous cleaning vehicle is 186 m3/h. Due to the high efficiency and high-pressure requirement, backward curved radial fan type was preferred in the suction system of the autonomous cleaning vehicle. CAD files were obtained by using Solidworks program with the help of theoretical results for radial fan design. For analysis, CFD analysis studies were carried out with the help of the Fluent program in the Ansys program. In order to obtain optimum results during the analysis phase, some parameters were changed on the radial fan geometry and the analyzes were repeated under the same boundary conditions. Simulation studies were carried out by changing the blade angle, which is one of the blade parameters of the radial fan, with design updates. The β1 parameter, which is the blade inlet angle of the radial fan, is kept constant and the β2 parameter, which is the blade outlet angle, is changed, and the β2 parameter is kept constant and the β1 parameter is changed, and the obtained data are compared. Then, the speed and pressure values were examined by making changes in the number of different blades according to the different blade angle conditions of the radial fan. With the changes to be made in the blade structure of the fan, the final fan design, in which the suction can reach the desired level, has been obtained to increase the pressure difference, considering the blade angle and flow rate difference. Afterwards, experimental studies were carried out and fan performance parameters were obtained. The ideal fan is produced by obtaining the ideal fan design. Since it is aimed to be used in an autonomous vehicle, it must work with a DC motor. A 24V-600W DC motor is used to rotate at 20000 rpm. In order to run the DC motor with AC electricity, two 12V-30A transformers were connected in series and 720W power of 24V-30A was obtained. Two 10A diode circuit elements are used to ensure unilateral current in transformers. The elements are brought together to ensure the operation of the radial fan. The obtained analysis results and the experimental results were compared with each other.