Design and Development of a Remote-Control Test Bench for Remote Piloted Aircraft\u27s Brushless Motors

The present paper is focused on designing and manufacturing a remote-control test bench for RPA\u27s brushless motors. The main components of the testing bench (structural, mechanical and electric components) are presented, how they are coupled, and the operating principle. The test bench is characterized by five emergency systems, one manual and four automated emergency systems that can stop the test under different conditions to avoid damaging the motor. To validate the testing bench, a SK3-5045 660 kV electric motor was selected along with a carbon fibre reinforced composite propeller. It was experimentally demonstrated that the test bench was fully automated, there were measured the propulsion force, current intensity, voltage, but also the consumed power of a motor intended for an RPA. The test results were used to determine the motorization performance and power consumption of an RPA designed with four electric motors (quadcopter type)

Experimental Transient Process Analysis of Micro-Turbojet Aviation Engines: Comparing the Effects of Diesel and Kerosene Fuels at Different Ambient Temperatures

In this paper, we investigate the impact of diesel and kerosene on the transient processes occurring in a micro-turbojet aviation engine. The experiments were conducted under two distinct ambient temperature conditions, 0 and 20 °C. Specifically, we analyzed the starting phase of the micro-engine while operating with kerosene and diesel at both ambient temperature settings. Comparative graphs were generated, and the starting time was meticulously examined. Subsequently, we constructed performance maps for the engine using both fuels and across the two ambient temperature scenarios. We then executed a transient process, comprising sudden acceleration and deceleration, under the aforementioned ambient temperature conditions and with both fuels. The fluctuations in temperature within the combustion chamber, thrust force, and fuel consumption are presented for both rapid acceleration and deceleration events. Furthermore, we conducted comparisons between the thrust force, fuel flow rate, combustion chamber temperature, and specific fuel consumption for the two fuels tested and under the two ambient temperature conditions, both during idle and at higher engine regimes. In the idle regime at 0 °C, the kerosene flow is about 0.78% higher than diesel, with the kerosene thrust approximately 1.92% greater. At 20 °C, the kerosene consumption rises by roughly 5.56% compared to diesel, while the thrust increases by about 1.38%. It was observed that at the maximum operating regime, at 0 °C, the kerosene flow exceeds diesel by around 6%, with the kerosene thrust slightly higher, by about 0.63%. At 20 °C, the kerosene consumption rises by roughly 13.19% compared to diesel, while the thrust increases by about 5.91%. In higher regimes, the kerosene consumption surpasses diesel, but the thrust increase is not significant. Thus, diesel’s use as a fuel for the microturbo engine is justified due to its lower consumption at both 0 °C and 20 °C

Lab Scale Investigation of Gaseous Emissions, Performance and Stability of an Aviation Turbo-Engine While Running on Biodiesel Based Sustainable Aviation Fuel

The research experimentally examines the viability of biodiesel obtained from pork fat (BP) as a sustainable aviation fuel (SAF) when mixed with kerosene (Ke)—Jet-A aviation fuel + 5% Aeroshell 500 oil. Various blends of biodiesel and kerosene (10, 20, and 30% vol. of BP added in Ke) were subjected to testing in an aviation micro turbo-engine under different operational states: idle, cruise, and maximum power. During the tests, monitoring of engine parameters such as burning temperature, fuel consumption, and thrust force was conducted. The study also encompassed the calculation of crucial performance indicators like burning efficiency, thermal efficiency, and specific consumption for all fuel blends under maximum power conditions. Combustion temperatures ahead of the turbines rise with an increase in biodiesel concentration, particularly in the idle regime, without compromising engine integrity. However, for regimes 2 and 3, the temperature in front of the turbine decreases with rising biodiesel concentration, accompanied by an increase in fuel flow rate. This phenomenon is reflected in the elevated specific consumption. Notably, for regime 3, there is a noticeable rise in specific consumption, starting from S = 0.0264 kg/Nh when the turbo-engine operates solely with Ke, to S = 0.0266 kg/Nh for Ke + 10% BP, S = 0.0269 kg/Nh for Ke + 20% BP, and S = 0.0275 kg/Nh for Ke + 30% BP. Physical–chemical properties of the blends, encompassing density, viscosity, flash point, and calorific power, were determined. Furthermore, elemental analysis and FTIR were used for chemical composition determination. The amount of CO2 produced during the stoichiometric combustion reaction with air showed variations. Initially, when using only Ke, it amounted to 3.12 kg per kilogram of fuel. Upon adding 10% BP, this value decreased to 3.09 kg, further reducing to 3.05 kg with 20% BP. The lowest value was observed with 30% BP, reaching 3.04 kg. Experimental assessments were performed on the Jet Cat P80® micro-turbo-engine, covering aspects such as starting procedures, sudden acceleration, sudden deceleration, and emissions of pollutants (NOx, CO, and SO2) during several engine operational phases. The outcomes reveal that the examined fuel blends exhibited stable engine performance across all tested conditions. This indicates that these blends hold promise as sustainable aviation fuels for micro turbo-engines, presenting benefits in terms of diminished pollution and a more ecologically sound raw material base for fuel production

Optimizing ideal ion propulsion systems depending on the nature of the propellant

From all accounts the ion thrusters are characterized by the fact that they produce a very high exhaust velocity and specific impulse, sometimes too high for many missions. The exhaust velocity of the ionized particles is a function of the ratio between electrical charge and mass. The obvious solution is the use of ions with low electrical charge – mass ratio, but many of these substances have a corrosive effect on the acceleration grids, they are toxic and hard to store on board the spacecraft. Currently the most used propellant for the ionic propulsion systems is xenon gas having many advantages, but it is expensive when compared to other propellants. The current paper aims to make an optimization study of ideal ion thrusters depending on the nature of the propellant using for studying a significant number of substances. It will study the variation of the performances: force, specific impulse, efficiency, etc for the same power available on board, for the same accelerating voltage and the same ionic current

Acoustic investigation on nozzles with different types of six lobed chevrons

This paper deals with a few aspects of the notion of chevron and the process that helps reducing the noise pollution. Based on the gas dynamic and geometrical parameters of a single flow jet engine a model of CFD data processing is made. In this process the influence of chevrons on acoustic wave intensity produced by the jet can be observed. A series of tests on six lobed triangular chevrons are discussed in order to settle the influence of the geometrical parameters on the flow and on the jet acoustics. Finally the paper presents the contribution of chevrons in noise pollution reduction

Experimental Evaluation of Methanol/Jet-A Blends as Sustainable Aviation Fuels for Turbo-Engines: Performance and Environmental Impact Analysis

This study offers a comprehensive examination, both theoretically and experimentally, of the potential of methanol (M) as a sustainable aviation fuel (SAF) assessed in combination with kerosene (Ke—Jet-A aviation fuel + 5% Aeroshell oil). Different blends of methanol and kerosene (10%, 20%, and 30% vol. of (M) was added to Ke) were tested in an aviation micro turbo-engine under various operating regimes, such as idle, cruise, and maximum. Key engine parameters, including combustion temperature, fuel consumption, and thrust, were closely monitored during these trials. Essential performance indicators such as combustion efficiency, thermal efficiency, and specific consumption for all fuel blends under maximum operating conditions are also presented. Physical and chemical characteristics, such as viscosity, density, calorific value and flash point, were determined for each blend. Moreover, elemental analysis and FTIR spectroscopy were utilized to evaluate the chemical composition of the fuels. This study further investigated the air requirements for stoichiometric combustion and computed the resulting CO2 and H2O emissions. Experimental tests were conducted on the Jet Cat P80® micro turbo-engine, covering assessments of starting procedures, acceleration, deceleration, and pollutant emissions (CO and SO2) during various engine operating conditions. The results suggest that the examined fuel blends demonstrate stable engine performance at concentrations of 10% and 20% methanol. However, observations indicate that with an increase in methanol concentration, particularly at 30%, the stability of the engine at idle and, notably, at maximum speed decreases significantly. Specifically, at a 30% methanol concentration, the engine no longer operates stably, exhibiting significant rpm fluctuations, leading to the decision not to explore higher concentrations

Noise Impact Mitigation of Shopping Centres Located near Densely Populated Areas for a Better Quality of Life

The growth of the urban population and its activity in major cities has led to various public health challenges, including environmental pollution, which are reflected in a decrease in the well-being of societies. This paper presents a predictive tool used to mitigate the noise impact study of commercial centre noise on the surrounding houses, the study being conducted prior to its construction. Before the construction of the supermarket, the sound pressure levels from the façade of the surrounding building are measured to have a background noise level of the analysed area. The noise impact study is made using prediction software in which the houses and the shopping centre buildings are numerically modelled. The main noise sources of the commercial centre, defined in numerical predictions, are represented by the air conditioners, heat pumps situated on the roof and the noise generated by the activities from the supply ramp. The noise impact evaluation is performed at different heights and by determining the number of affected inhabitants. To reduce the number of exposed inhabitants to noise, four technical solutions are presented. The proposed noise solutions are based on technical and economic analyses and also on the urban landscape. The study presents the noise prediction for which the propagation calculus was made according to ISO 9613-2. The noise limits were evaluated according to the Romanian national legislation. The final part of this study presents the noise measurements performed after the construction of this shopping centre and the validation of the implemented noise reduction solution

Rocket Solid Propellant Alternative Based on Ammonium Dinitramide

Due to the continuous run for a green environment the current article proposes a new type of solid propellant based on the fairly new synthesized oxidizer, ammonium dinitramide (ADN). Apart of having a higher specific impulse than the worldwide renowned oxidizer, ammonium perchlorate, ADN has the advantage, of leaving behind only nitrogen, oxygen and water after decomposing at high temperatures and therefore totally avoiding the formation of hydrogen chloride fumes. Based on the oxidizer to fuel ratios of the current formulations of the major rocket solid booster (e.g. Space Shuttle’s SRB, Ariane 5’s SRB) which comprises mass variations of ammonium perchlorate oxidizer (70-75%), atomized aluminum powder (10-18%) and polybutadiene binder (12-20%) a new solid propellant was formulated. As previously stated, the new propellant formula and its variations use ADN as oxidizer and erythritol tetranitrate as fuel, keeping the same polybutadiene as binder

Acoustic control study of turbofan nozzles with triangular chevrons

This paper has a small part dealing with the notion of chevron and the process that helps reducing the noise pollution. Based on the gas dynamics and the geometrical parameters of the turbofan jet engine a model of CFD data processing is created. In this process the influence of chevrons on acoustic wave intensity produced by the jet is observed by analyzing this process. A series of tests have been made on 10 si 20 lobed chevrons. The combination between them and the 7 resulting cases have been studied, namely the triangular chevrons in order to settle the influence of the geometrical parameters on the flow and on the jet acoustics. Finally the contribution of the chevrons in noise pollution reduction has been highlighted

Impact of Using Chevrons Nozzle on the Acoustics and Performances of a Micro Turbojet Engine

This paper presents a study regarding the noise reduction of the turbojet engine, in particular the jet noise of a micro turbojet engine. The results of the measurement campaign are presented followed by a performances analysis which is based on the measured data by the test bench. Within the tests, beside the baseline nozzle other two nozzles with chevrons were tested and evaluated. First type of nozzle is foreseen with eight triangular chevrons, the length of the chevrons being L = 10 percentages from the equivalent diameter and an immersion angle of I = 0 deg. For the second nozzle the length and the immersion angle were maintained, only the chevrons number were increased at 16. The micro turbojet engine has been tested at four different regimes of speed. The engine performances were monitored by measuring the fuel flow, the temperature in front of the turbine, the intake air flow, the compression ratio, the propulsion force and the temperature before the compressor. In addition, during the testing, the vibrations were measured on axial and radial direction which indicate a normal functioning of the engine during the chevron nozzles testing. Regarding the noise, it was concluded that at low regimes the noise doesn’t presents any reduction when using the chevron nozzles, while at high regimes an overall noise reduction of 2–3 dB(A) was achieved. Regarding the engine performances, a decrease in the temperature in front of the turbine, compression ratio and the intake air and fuel flow was achieved and also a drop of few percent of the propulsion force