Doru Luculescu - Academia.edu (original) (raw)

Papers by Doru Luculescu

SCIENTIFIC RESEARCH AND EDUCATION IN THE AIR FORCE, 2022

Compressor and turbine blades, used in the construction of aircraft turboprop engines, are very i... more Compressor and turbine blades, used in the construction of aircraft turboprop engines, are very important constructive elements, by their functional role, and complex by geometric parameters, mechanical and gas-dynamic factors. This paper aims to present a method of probabilistic design of the assembly between the rotor disk and the compressor and turbine blades.

AIP Conference Proceedings, 2016

The main objective of this paper is to describe the key physical features for modelling the unste... more The main objective of this paper is to describe the key physical features for modelling the unsteady aerodynamic effects found on helicopter rotor blade operating under nominally attached flow conditions away from stall. The unsteady effects were considered as phase differences between the forcing function and the aerodynamic response, being functions of the reduced frequency, the Mach number and the mode forcing. For a helicopter rotor, the reduced frequency at any blade element can’t be exactly calculated but a first order approximation for the reduced frequency gives useful information about the degree of unsteadiness. The sources of unsteady effects were decomposed into perturbations to the local angle of attack and velocity field. The numerical calculus and graphics were made in FLUENT and MAPLE soft environments. This mathematical model is applicable for aerodynamic design of wind turbine rotor blades, hybrid energy systems optimization and aeroelastic analysis.

Review of the Air Force Academy

The main power transmission of helicopters is a complex technical system, which fulfills its func... more The main power transmission of helicopters is a complex technical system, which fulfills its functional role of transforming the kinematic parameters from the turboshaft into the kinematic parameters necessary for the optimal operation of the main rotor of the helicopter. The paper presents a method of kinematic analysis of the power transmission for the main rotor and the anti-torque rotor of a helicopter. Based on the kinematic diagram of this mechanical transmission, the angular velocities and the transmission ratios achieved by the double-planetary gearbox of the main and the secondary transmission are determined.

In this paper, we give conditions for a rate of convergence of Fisher information J and relative ... more In this paper, we give conditions for a rate of convergence of Fisher information J and relative entropy D in the Central Limit Theorem. We use the Poincaré inequality and the theory of projections in to provide a better understanding of the decrease in Fisher information implied by results of Barron and Brown. ) / 1 ( n O 2

Advances in Materials Science and Engineering, 2015

The current paper has been written in order to find the best solutions to replace the antitorque ... more The current paper has been written in order to find the best solutions to replace the antitorque rotor of single-rotor helicopters, with removal of its disadvantages through the Coandă Effect. This would significantly increase the flight performance. The research mainly aims at obtaining a controlled lateral force due to Coandă flows through the tail boom, a force which would be useful for the stabilization needed because of the lifting rotor during the flight of single-rotor helicopters.

The current paper has been written in order to find the best solutions to replace the antitorque ... more The current paper has been written in order to find the best solutions to replace the antitorque rotor of single-rotor helicopters, with removal of its disadvantages through the Coandă Effect.This would significantly increase the flight performance.The research mainly aims at obtaining a controlled lateral force due to Coandă flows through the tail boom, a force which would be useful for the stabilization needed because of the lifting rotor during the flight of single-rotor helicopters.

Applied Mechanics and Materials, 2015

In this paper are presented some CFD results regarding combustion in an aircraft turbojet engine,... more In this paper are presented some CFD results regarding combustion in an aircraft turbojet engine, for aviation fuels consisting of hydrocarbon mixtures. Recent achievements in chemical kinetic modeling of kerosene combustion are presented. Performance parameters investigated were combustion efficiency, unburned hydrocarbons as well as liner temperatures and smoke. The analysis is based on the theoretically and experimentally characteristics of a typical axial flow engine.

Review of the Air Force Academy

This paper analyzes a method of evaluating the reliability of the rolling bearing in anti-aircraf... more This paper analyzes a method of evaluating the reliability of the rolling bearing in anti-aircraft guns. In evaluating its reliability, the factors that depend on the operating conditions of the anti-aircraft gun are taken into account, as well as the factors of design, technology, materials and assembly

Review of the Air Force Academy, Dec 14, 2017

The present paper proposes a method of evaluating the reliability of demountable assemblies with ... more The present paper proposes a method of evaluating the reliability of demountable assemblies with catching devices. After there have been identified the random variables that intervened in the sizing calculation, reliability of this type of assembly is being determined.

SCIENTIFIC RESEARCH AND EDUCATION IN THE AIR FORCE, Jun 24, 2016

The multi-copter UAV landing gear is used for ground station and shock damping for landings. The ... more The multi-copter UAV landing gear is used for ground station and shock damping for landings. The materials used in the construction of landing gears are selected by using a simple criterion: minimal mass versus maxim resistance at shocks. Article contains an evaluation of a kinematics mechanism quadrilateral landing gear is mounted on a multicopter.

MATEC Web of Conferences

The purpose of the research is to develop a model for the analysis of investments in connectivity... more The purpose of the research is to develop a model for the analysis of investments in connectivity. The developed model allows a more accurate capture of the impact of sources of fluctuations in investment projects aimed at increasing connectivity, using Wiener Processes and Poisson distribution. The results are solutions for improved decision-making in aviation infrastructure to the benefit of the regional economy.

MATEC Web of Conferences

Using of the flying wing (the UAVs category) in various fields (civilian and military) determine ... more Using of the flying wing (the UAVs category) in various fields (civilian and military) determine interests sustained of the aerodynamic and trajectory optimizations. The article presents analysis of wing flying performance (in morphing concept) by studying optimizing the maneuvers control and wind tunnel tests.

2008 11th International Conference on Optimization of Electrical and Electronic Equipment, 2008

In this work is presented an analytical method of determining the provisional reliability of the ... more In this work is presented an analytical method of determining the provisional reliability of the bearings used in bearing of asynchronous electric motors' axles. The durability of the bearings is limited by "hereditary" factors such designing, technology, material, assembly, and also by factors of their use, for example the bearings loads, respectively the quality of lubricant. The evaluation of reliability of the bearings represents, in general, an initial stage in the calculation of the reliability of component elements of a complex electro-mechanic system, namely of an induction motor. The proposed model for evaluation of provisional reliability represents a logical continuation of the main stages that are performed in designing of a bearing assembly, and that has as basis the probability theory and the mathematical statistics methods, proper to the random character of the materials' properties, variation of the stresses and proper to the component elements dimensions.

The main objective of this paper is to describe the key physical features for modelling the unste... more The main objective of this paper is to describe the key physical features for modelling the unsteady aerodynamic effects found on helicopter rotor blade operating under nominally attached flow conditions away from stall. The unsteady effects were considered as phase differences between the forcing function and the aerodynamic response, being functions of the reduced frequency, the Mach number and the mode forcing. For a helicopter rotor, the reduced frequency at any blade element can’t be exactly calculated but a first order approximation for the reduced frequency gives useful information about the degree of unsteadiness. The sources of unsteady effects were decomposed into perturbations to the local angle of attack and velocity field. The numerical calculus and graphics were made in FLUENT and MAPLE soft environments. This mathematical model is applicable for aerodynamic design of wind turbine rotor blades, hybrid energy systems optimization and aeroelastic analysis.

2008 11th International Conference on Optimization of Electrical and Electronic Equipment, May 22, 2008

In this work is presented an analytical method of determining the provisional reliability of the ... more In this work is presented an analytical method of determining the provisional reliability of the bearings used in bearing of asynchronous electric motors' axles. The durability of the bearings is limited by "hereditary" factors such designing, technology, material, assembly, and also by factors of their use, for example the bearings loads, respectively the quality of lubricant. The evaluation of reliability of the bearings represents, in general, an initial stage in the calculation of the reliability of component elements of a complex electro-mechanic system, namely of an induction motor. The proposed model for evaluation of provisional reliability represents a logical continuation of the main stages that are performed in designing of a bearing assembly, and that has as basis the probability theory and the mathematical statistics methods, proper to the random character of the materials' properties, variation of the stresses and proper to the component elements dimensions.

Journal of Physics: Conference Series

SCIENTIFIC RESEARCH AND EDUCATION IN THE AIR FORCE, 2022

Compressor and turbine blades, used in the construction of aircraft turboprop engines, are very i... more Compressor and turbine blades, used in the construction of aircraft turboprop engines, are very important constructive elements, by their functional role, and complex by geometric parameters, mechanical and gas-dynamic factors. This paper aims to present a method of probabilistic design of the assembly between the rotor disk and the compressor and turbine blades.

AIP Conference Proceedings, 2016

The main objective of this paper is to describe the key physical features for modelling the unste... more The main objective of this paper is to describe the key physical features for modelling the unsteady aerodynamic effects found on helicopter rotor blade operating under nominally attached flow conditions away from stall. The unsteady effects were considered as phase differences between the forcing function and the aerodynamic response, being functions of the reduced frequency, the Mach number and the mode forcing. For a helicopter rotor, the reduced frequency at any blade element can’t be exactly calculated but a first order approximation for the reduced frequency gives useful information about the degree of unsteadiness. The sources of unsteady effects were decomposed into perturbations to the local angle of attack and velocity field. The numerical calculus and graphics were made in FLUENT and MAPLE soft environments. This mathematical model is applicable for aerodynamic design of wind turbine rotor blades, hybrid energy systems optimization and aeroelastic analysis.

Review of the Air Force Academy

The main power transmission of helicopters is a complex technical system, which fulfills its func... more The main power transmission of helicopters is a complex technical system, which fulfills its functional role of transforming the kinematic parameters from the turboshaft into the kinematic parameters necessary for the optimal operation of the main rotor of the helicopter. The paper presents a method of kinematic analysis of the power transmission for the main rotor and the anti-torque rotor of a helicopter. Based on the kinematic diagram of this mechanical transmission, the angular velocities and the transmission ratios achieved by the double-planetary gearbox of the main and the secondary transmission are determined.

In this paper, we give conditions for a rate of convergence of Fisher information J and relative ... more In this paper, we give conditions for a rate of convergence of Fisher information J and relative entropy D in the Central Limit Theorem. We use the Poincaré inequality and the theory of projections in to provide a better understanding of the decrease in Fisher information implied by results of Barron and Brown. ) / 1 ( n O 2

Advances in Materials Science and Engineering, 2015

The current paper has been written in order to find the best solutions to replace the antitorque ... more The current paper has been written in order to find the best solutions to replace the antitorque rotor of single-rotor helicopters, with removal of its disadvantages through the Coandă Effect. This would significantly increase the flight performance. The research mainly aims at obtaining a controlled lateral force due to Coandă flows through the tail boom, a force which would be useful for the stabilization needed because of the lifting rotor during the flight of single-rotor helicopters.

The current paper has been written in order to find the best solutions to replace the antitorque ... more The current paper has been written in order to find the best solutions to replace the antitorque rotor of single-rotor helicopters, with removal of its disadvantages through the Coandă Effect.This would significantly increase the flight performance.The research mainly aims at obtaining a controlled lateral force due to Coandă flows through the tail boom, a force which would be useful for the stabilization needed because of the lifting rotor during the flight of single-rotor helicopters.

Applied Mechanics and Materials, 2015

In this paper are presented some CFD results regarding combustion in an aircraft turbojet engine,... more In this paper are presented some CFD results regarding combustion in an aircraft turbojet engine, for aviation fuels consisting of hydrocarbon mixtures. Recent achievements in chemical kinetic modeling of kerosene combustion are presented. Performance parameters investigated were combustion efficiency, unburned hydrocarbons as well as liner temperatures and smoke. The analysis is based on the theoretically and experimentally characteristics of a typical axial flow engine.

Review of the Air Force Academy

This paper analyzes a method of evaluating the reliability of the rolling bearing in anti-aircraf... more This paper analyzes a method of evaluating the reliability of the rolling bearing in anti-aircraft guns. In evaluating its reliability, the factors that depend on the operating conditions of the anti-aircraft gun are taken into account, as well as the factors of design, technology, materials and assembly

Review of the Air Force Academy, Dec 14, 2017

The present paper proposes a method of evaluating the reliability of demountable assemblies with ... more The present paper proposes a method of evaluating the reliability of demountable assemblies with catching devices. After there have been identified the random variables that intervened in the sizing calculation, reliability of this type of assembly is being determined.

SCIENTIFIC RESEARCH AND EDUCATION IN THE AIR FORCE, Jun 24, 2016

The multi-copter UAV landing gear is used for ground station and shock damping for landings. The ... more The multi-copter UAV landing gear is used for ground station and shock damping for landings. The materials used in the construction of landing gears are selected by using a simple criterion: minimal mass versus maxim resistance at shocks. Article contains an evaluation of a kinematics mechanism quadrilateral landing gear is mounted on a multicopter.

MATEC Web of Conferences

The purpose of the research is to develop a model for the analysis of investments in connectivity... more The purpose of the research is to develop a model for the analysis of investments in connectivity. The developed model allows a more accurate capture of the impact of sources of fluctuations in investment projects aimed at increasing connectivity, using Wiener Processes and Poisson distribution. The results are solutions for improved decision-making in aviation infrastructure to the benefit of the regional economy.

MATEC Web of Conferences

Using of the flying wing (the UAVs category) in various fields (civilian and military) determine ... more Using of the flying wing (the UAVs category) in various fields (civilian and military) determine interests sustained of the aerodynamic and trajectory optimizations. The article presents analysis of wing flying performance (in morphing concept) by studying optimizing the maneuvers control and wind tunnel tests.

2008 11th International Conference on Optimization of Electrical and Electronic Equipment, 2008

In this work is presented an analytical method of determining the provisional reliability of the ... more In this work is presented an analytical method of determining the provisional reliability of the bearings used in bearing of asynchronous electric motors' axles. The durability of the bearings is limited by "hereditary" factors such designing, technology, material, assembly, and also by factors of their use, for example the bearings loads, respectively the quality of lubricant. The evaluation of reliability of the bearings represents, in general, an initial stage in the calculation of the reliability of component elements of a complex electro-mechanic system, namely of an induction motor. The proposed model for evaluation of provisional reliability represents a logical continuation of the main stages that are performed in designing of a bearing assembly, and that has as basis the probability theory and the mathematical statistics methods, proper to the random character of the materials' properties, variation of the stresses and proper to the component elements dimensions.

The main objective of this paper is to describe the key physical features for modelling the unste... more The main objective of this paper is to describe the key physical features for modelling the unsteady aerodynamic effects found on helicopter rotor blade operating under nominally attached flow conditions away from stall. The unsteady effects were considered as phase differences between the forcing function and the aerodynamic response, being functions of the reduced frequency, the Mach number and the mode forcing. For a helicopter rotor, the reduced frequency at any blade element can’t be exactly calculated but a first order approximation for the reduced frequency gives useful information about the degree of unsteadiness. The sources of unsteady effects were decomposed into perturbations to the local angle of attack and velocity field. The numerical calculus and graphics were made in FLUENT and MAPLE soft environments. This mathematical model is applicable for aerodynamic design of wind turbine rotor blades, hybrid energy systems optimization and aeroelastic analysis.

2008 11th International Conference on Optimization of Electrical and Electronic Equipment, May 22, 2008

In this work is presented an analytical method of determining the provisional reliability of the ... more In this work is presented an analytical method of determining the provisional reliability of the bearings used in bearing of asynchronous electric motors' axles. The durability of the bearings is limited by "hereditary" factors such designing, technology, material, assembly, and also by factors of their use, for example the bearings loads, respectively the quality of lubricant. The evaluation of reliability of the bearings represents, in general, an initial stage in the calculation of the reliability of component elements of a complex electro-mechanic system, namely of an induction motor. The proposed model for evaluation of provisional reliability represents a logical continuation of the main stages that are performed in designing of a bearing assembly, and that has as basis the probability theory and the mathematical statistics methods, proper to the random character of the materials' properties, variation of the stresses and proper to the component elements dimensions.

Journal of Physics: Conference Series