Propeller Effect Research Articles

Modeling and Closed Loop Flight Testing of a Fixed Wing Micro Air Vehicle.

This paper presents the nonlinear six degrees of freedom dynamic modeling of a fixed wing micro air vehicle. The static derivatives of the micro air vehicle are obtained through the wind tunnel testing. The propeller effects on the lift, drag, pitching moment and side force are quantified through wind tunnel testing. The dynamic derivatives are obtained through empirical relations available in the literature. The trim conditions are computed for a straight and constant altitude flight condition. The linearized longitudinal and lateral state space models are obtained about trim conditions. The variations in short period mode, phugoid mode, Dutch roll mode, roll subsidence mode and spiral mode with respect to different trim operating conditions is presented. A stabilizing static output feedback controller is designed using the obtained model. Successful closed loop flight trials are conducted with the static output feedback controller.

On the timing behaviour of PSR B1259–63 under the propeller torque from a transient accretion disc

The $\gamma$-ray pulsar binary system PSR B1259-63 flares in GeV after each periastron. The origin of those flares is still under debate. Recently, [2017ApJ...844..114Y] proposed a mechanism that might explain the GeV flares. In that model, a transient accretion disc is expected to be formed from the matter which was gravity-captured by the neutron star from the main sequence companion's circumstellar disc. The transient accretion disc exerts a spin down torque on the neutron star (propeller effect), which might be traceable via pulsar timing observation of PSR B1259-63. In this paper, we phenomenologically consider the propeller effect with a parameter $\chi$, which describes the coupling between the disc matter and the neutron star. Comparing the expected timing residuals against the recent observation in [2014MNRAS.437.3255S], we conclude that the angular momentum transfer is very weak (with the coupling parameter $\chi\le10^{-4}$).

Development of numerical method to simulate flows around a ship at propulsion conditions in regular waves coupling with the ship propulsion plant model

A numerical method to simulate flows with propeller effects including the response of a ship propulsion plant has been developed. The dynamics of a ship propulsion plant is modeled by the function of the diesel engine control system. Propeller torque which is computed by the propeller model with the interaction to the flow fields is put into the ship propulsion plant model, then, the propeller rotational speed is obtained by solving the equation of the rotational motion of a propeller shaft line. Present method can reproduce the fluctuations of propeller rotational speed and torque in the condition with the regular head waves. The amplitude of fluctuations shows agreement with the measured data. The detailed analysis of the flow fields with ship motions which is difficult to be obtained at experiments is also carried out.

Identificación de Parámetros de Desempeño de un UAV a Través de Vuelos de Prueba

The design and implementation of a autonomous navigation and control system for UAV, mandates simulating the system before in-flight testing. These simulations require a computational model of the aircraft, that can be obtained from the computation of aerodynamic parameters such as the drag polar. In this paper we present the identification of these parameters using two methods: one by flight testing techniques; the other by a combination of semi-empirical methods and computational fluid dynamics, dubbed the hybrid method. The hybrid method, which produces a parabolic polar drag, had the same qualitative trend compared to experiments. However, a detailed analysis of the parameters that shapes the polar drag, had significant differences, particularly in the parasite drag. This is probably due to propeller effects, low Reynolds Number and limitations of the piloting technique.Keywords: Drag polar, flight testing, parasite drag, UAV, VLM

밸러스트 흘수 조건에서 5만톤급 석유화학제품 운반선의 엔진 부하에 따른 프로펠러 편심 추력이 축 거동 및 지지베어링에 미치는 영향 연구

밸러스트 흘수 조건에서 5만톤급 석유화학제품 운반선의 엔진 부하에 따른 프로펠러 편심 추력이 축 거동 및 지지베어링에 미치는 영향 연구

Research on Radar Micro-Doppler Feature Parameter Estimation of Propeller Aircraft

The micro-motion modulation effect of the rotated propellers to radar echo can be a steady feature for aircraft target recognition. Thus, micro-Doppler feature parameter estimation is a key to accurate target recognition. In this paper, the radar echo of rotated propellers is modelled and simulated. Based on which, the distribution characteristics of the micro-motion modulation energy in time, frequency and time-frequency domain are analyzed. The micro-motion modulation energy produced by the scattering points of rotating propellers is accumulated using the Inverse-Radon (I-Radon) transform, which can be used to accomplish the estimation of micro-modulation parameter. Finally, it is proved that the proposed parameter estimation method is effective with measured data. The micro-motion parameters of aircraft can be used as the features of radar target recognition.

Numerical analysis of propeller effects on wing aerodynamic: tip mounted and distributed propulsion

Abstract The purpose of this investigation is determinate the effects of propeller on wing aerodynamic, both for a propeller mounted in the middle of the wing, and for tip mounted propeller. Especially, it is investigated how a tip-mounted propeller can decrease wing induced drag, and how distributed propulsion can increase the high-lift aerodynamic. Analyses are carried out using a Virtual Disk Model on CFD software, showing a good agreement comparing numerical results with experimental data obtained by previous works. Wing tip engine with propeller, has been employed on a general aviation aircraft wing with an installed thrust to accomplish with cruise performance, reducing the induced drag. Distributed propeller engines on the wing allows improving of low speed performance, increasing the aircraft lift coefficient. Induced drag can be reduced of about 2-3% a low cruise lift coefficient, until 8-10% at relative high cruise lift coefficient. Maximum achievable lift coefficient could be increased of about 20-30% in clean configuration, and more than 50% in flapped configuration.

Studying the accretion geometry of EXO 2030+375 at luminosities close to the propeller regime

The Be X-ray binary EXO 2030+375 was in an extended low luminosity state during most of 2016. We observed this state with NuSTAR and Swift, supported by INTEGRAL observations as well as optical spectroscopy with the NOT. We present a comprehensive spectral and timing analysis of these data here to study the accretion geometry and investigate a possible onset of the propeller effect. The H-alpha data show that the circumstellar disk of the Be-star is still present. We measure equivalent widths similar to values found during more active phases in the past, indicating that the low-luminosity state is not simply triggered by a smaller Be disk. The NuSTAR data, taken at a 3-78 keV luminosity of ~6.8e35 erg/s (for a distance of 7.1 kpc), are well described by standard accreting pulsar models, such as an absorbed power-law with a high-energy cutoff. We find that pulsations are still clearly visible at these luminosities, indicating that accretion is continuing despite the very low mass transfer rate. In phase-resolved spectroscopy we find a peculiar variation of the photon index from ~1.5 to ~2.5 over only about 3% of the rotational period. This variation is similar to that observed with XMM-Newton at much higher luminosities. It may be connected to the accretion column passing through our line of sight. With Swift/XRT we observe luminosities as low as 1e34 erg/s during which the data quality did not allow us to search for pulsations, but the spectrum is much softer and well described by either a blackbody or soft power-law continuum. This softer spectrum might be due to the fact that accretion has been stopped by the propeller effect and we only observe the neutron star surface cooling.

Investigation on Propeller Slipstream by Using an Unstructured Rans Solver Based on Overlapping Grids

AbstractBased on unstructured hybrid grid and dynamic overlapping grid technique, numerical simulations of Unsteady Reynolds Averaged Navier-Stokes equations were performed and investigation on isolated propeller aerodynamic characteristics and effects of propeller slipstream on turboprops were undertaken. The computational grid consisted of rotational subzone of propeller and stationary major-zone of aircraft, and walls criterion was used in the automatic hole-cutting procedure. Distance weight interpolation and tri-linear interpolation were developed to transfer information between the rotational and stationary subzones. The boundaries of overlapping grids were optimized for fixed axis rotation. The governing equations were solved by dual-time method and Lower Upper-Symmetric Gauss-Seidel method. The method and grid technique were verified by isolated propeller configuration and the computational results were in well agreement with the experimental data. The grid independence was studied to establish the numerical results. Finally, the flow around a turboprop case was simulated and the influence of propeller slipstream was presented by analyzing the surface pressure contours, profile pressure distribution, vorticity contours and profile streamline. It's indicated that the slipstream accelerates and rotates the free stream flow, changing the local angle of attack, enhancing the downwash effects, affecting the pressure distribution on wing and horizontal tail, as well as increasing the drag coefficient, pitching moment coefficient and the slope of lift coefficient.

Dynamic analysis of continuous-flow microwave reactor with a screw propeller

To solve nonuniform heating when microwave energy is applied in a continuous-flow applicator, a microwave heating system with a screw propeller is designed. By introducing the implicit function and level set methods, the electromagnetic heat source input into the temperature field is updated with the rotation of the screw propeller. Combined with Arbitrary Lagrangian-Eulerian Formulation (ALE) machinery, the temperature distribution in the heating process is obtained. Water is taken as the sample in the experiment to verify the computational model. By using the proposed model, we also calculate the temperature distribution of two other commonly used liquids (ethylene glycol and glycerol). To analyze the effect of a screw propeller on heating uniformity, the temperature distribution of the cases with a screw propeller is quantitatively compared to that of the cases without a screw propeller.

Numerical estimation of bank-propeller-hull interaction effect on ship manoeuvring using CFD method

This paper presents a numerical investigation of ship manoeuvring under the combined effect of bank and propeller. The incompressible turbulent flow with free surface around the self-propelled hull form is simulated using a commercial CFD software (ANSYS-FLUENT). In order to estimate the influence of the bank-propeller effect on the hydrodynamic forces acting on the ship, volume forces representing the propeller are added to Navier-Stokes equations. The numerical simulations are carried out using the equivalent of experiment conditions. The validation of the CFD model is performed by comparing the numerical results to the available experimental data. For this investigation, the impact of Ship-Bank distance and ship speed on the bank effect are tested with and without propeller. An additional parameter concerning the advance ratio of the propeller is also tested.

Computation of Flow Field around Ship Hull including Self Propulsion Characteristics at Varying Rudder Positions

Flow field around different modern benchmark ship hull with self propulsion characteristics at varying longitudinal positions of rudder is computed using Computation Fluid Dynamics (CFD) technique. Numerical study is performed around bare hull first to determine free surface wave elevation and resistance components. Zonal approach is applied to incorporate ‘potential flow solver’ in the region outside the boundary layer & wake, ‘boundary layer solver’ in thin boundary layer region near the hull and ‘Navier Stokes solver’ in the wake region successively. Lifting Line method coupled with RANS solver is used to compute propeller open and self propulsion characteristics at different positions of rudder. Verification and validation studies for resistance coefficients have also been carried out using ITTC recommended procedure. The present computational method reveals that CFD results of flow field around ship hull with propeller and rudder effects are prospective and can be successfully applied in maritime industry.

The inner disc radius in the propeller phase and accretion-propeller transition of neutron stars

We have investigated the critical conditions required for a steady propeller effect for magnetized neutron stars with optically thick, geometrically thin accretion discs. We have shown through simple analytical calculations that a steady-state propeller mechanism cannot be sustained at an inner disc radius where the viscous and magnetic stresses are balanced. The radius calculated by equating these stresses is usually found to be close to the conventional Alfven radius for spherical accretion, r(A). Our results show that: (1) a steady propeller phase can be established with a maximum inner disc radius that is at least similar to 15 times smaller than rA depending on the mass-flow rate of the disc, rotational period and strength of the magnetic dipole field of the star, (2) the critical accretion rate corresponding to the accretion-propeller transition is orders of magnitude lower than the rate estimated by equating rA to the co-rotation radius. Our results are consistent with the properties of the transitional millisecond pulsars that show transitions between the accretion powered X-ray pulsar and the rotational powered radio-pulsar states.

The soft X-ray spectrum of the high-mass X-ray binary V0332+53 in quiescence

The propeller effect should cut off accretion in fast-spinning neutron star high mass X-ray binaries (HMXBs) at low mass transfer rates. However, accretion continues in some HMXBs at $L_{x} < 10^{34}$ erg s$^{-1}$, as evidenced by continuing pulsations. Indications of spectral softening in systems in the propeller regime suggest that some HMXBs are undergoing fundamental changes in their accretion regime. A 39 ks \textit{XMM-Newton} observation of the transient HMXB V0332+53 found it at a very low X-ray luminosity ($L_{x} \sim 4\times 10^{32}$ erg s${^{-1}}$). A power-law spectral fit requires an unusually soft spectral index ($4.4^{+0.9}_{-0.6}$), while a magnetized neutron star atmosphere model, with temperature \lt\ 6.7$\pm 0.2$ K and inferred emitting radius of $\sim0.2-0.3$ km, gives a good fit. We suggest that the quiescent X-ray emission from V0332+53 is mainly from a hot spot on the surface of the neutron star. We could not detect pulsations from V0332+53, due to the low count rate. Due to the high $N_H$, thermal emission from the rest of the neutron star could be only weakly constrained, to \lt\ $<$6.14$^{+0.05}_{-6.14}$ K, or $<3\times10^{33}$ erg s${^{-1}}$.

Transformation of chemical composition of snow in the impact areas of the first stage of the expandable launch system Proton in Central Kazakhstan

Snow cover contamination is assessed in the impact areas of the first stage of the expandable launch system Proton in Central Kazakhstan. It was revealed that the chemical effect ofpropellants on the snow cover is local. The increase in the content of the following high-toxic substances in the snow was registered: unsymmetrical dimethylhydrazine, nitrosodimethylamine, and nitrate and nitrite ions. The most part of the pollutants is localized in the upper 5-cm snow layer. Nitrogen tetroxide decreases the value of pH, and unsymmetrical dimethylhydrazine increases it. The inflow of calcareous soil particles to the atmosphere and their subsequent fallout result in the alkalization of snow and in the neutralization of acidification by nitrogen tetroxide accompanied by the formation ofthe salts of nitric acid and nitrous acid.

ATLAS IV wing aerodynamic design: From conceptual approach to detailed optimization

In this paper, the aerodynamic design of the ATLAS IV, remote controlled aircraft, is summarized. A wing aerodynamic design methodology was established for a high lift-high efficient aircraft, which participated at the International Competition: Air Cargo Challenge 2013 (ACC 2013), Lisbon, Portugal. The conceptual approach includes the basic design considerations regarding the regulations, the power consumption for efficient take-off and the maneuverability during operational conditions. At the next step, the preliminary design is elaborated using an advanced numerical method based on Linear Strip Theory (LST). This numerical method evaluates the results from the conceptual approach, increases the numerical accuracy of the initial concept and the results are used for the Aircraft's Dynamic Stability analysis. At the final step, a full CFD model was developed and calibrated based on preliminary design results. During the detail design, the propeller effects, a gurney flap and a winglet design were also investigated, for the further increase of ATLAS IV prototype's aerodynamic efficiency. The wing aerodynamic design procedure was used for the Team's strategy plan for the ACC 2013, improving its rank during the Contest.

MHD natural convection flow of viscoelastic fluid over an accelerating permeable surface with thermal radiation and heat source or sink: Spectral Homotopy Analysis Approach

Abstract An analysis is presented to study the effects of viscous dissipation and viscoelastic parameter on MHD natural convection flow of viscoelastic fluid over an accelerating permeable surface with thermal radiation and heat source/sink. The governing differential equations that are highly nonlinear are transformed by similarity variables and solved using Spectral Homotopy Analysis Method (SHAM). The effects of various pertinent parameters on the velocity and temperature profiles as well as the skin friction coefficient and the local Nusselt number are presented graphically and in tabular form. The SHAM results are compared favorably with already established results in literatures. It is found that the magnetic field acts as a retarding force on the velocity profile of the flow but has a propelling effect on the thermal condition of the flow. It was revealed that an increase in thermal radiation parameter of the flow produces significant increase in the thermal condition of the fluid temperature.

Multi-sliding surface control for the speed regulation system of ship diesel engines

The steady and reliable operation of a ship’s diesel engine is important to the ship’s electrical power system and the engine’s performance, and stable control of rotational speed is crucial to a diesel engine’s emission, economy and power performance. A ship’s diesel engine is a nonlinear and time-varying system. A traditional proportional–integral–derivative (PID) controller cannot regulate the speed under different working conditions. In this paper, a nonlinear mathematical model for speed regulation of diesel engines is established according to experiments and a multi-sliding surface variable structure controller for speed regulation of diesel engine is established by sliding mode control. A bulk cargo ship 500-I was analysed as an example. The MATLAB/Simulink simulation took the navigation environment and the effect of the ship propeller on the diesel engine into consideration. A simulation model considering the whole ship–engine–propeller system is built and some conclusions can be drawn from the simulation. The multi-sliding surface control can restrain the overshoot and realize a quick track of the targeted value with high accuracy and strong robustness. In addition, the fuel consumption and CO2 emission of this sliding mode variable structure control is reduced by 4.6% compared with traditional PID control.

Removing hydrochloric acid exhaust products from high performance solid rocket propellant using aluminum-lithium alloy

Hydrochloric acid (HCl) pollution from perchlorate based propellants is well known for both launch site contamination, as well as the possible ozone layer depletion effects. Past efforts in developing environmentally cleaner solid propellants by scavenging the chlorine ion have focused on replacing a portion of the chorine-containing oxidant (i.e., ammonium perchlorate) with an alkali metal nitrate. The alkali metal (e.g., Li or Na) in the nitrate reacts with the chlorine ion to form an alkali metal chloride (i.e., a salt instead of HCl). While this technique can potentially reduce HCl formation, it also results in reduced ideal specific impulse (ISP). Here, we show using thermochemical calculations that using aluminum-lithium (Al-Li) alloy can reduce HCl formation by more than 95% (with lithium contents ≥15 mass%) and increase the ideal ISP by ∼7s compared to neat aluminum (using 80/20 mass% Al-Li alloy). Two solid propellants were formulated using 80/20 Al-Li alloy or neat aluminum as fuel additives. The halide scavenging effect of Al-Li propellants was verified using wet bomb combustion experiments (75.5±4.8% reduction in pH, ∝ [HCl], when compared to neat aluminum). Additionally, no measurable HCl evolution was detected using differential scanning calorimetry coupled with thermogravimetric analysis, mass spectrometry, and Fourier transform infrared absorption.

Propeller effect in action in the ultraluminous accreting magnetar M82 X−2

We present here the first convincing observational manifestation of a magnetar-like magnetic field in an accreting neutron star in binary system - the first pulsating ultra-luminous X-ray source X-2 in the galaxy M82. Using the Chandra X-ray observatory data we show that the source exhibit the bimodal distribution of the luminosity with two well-defined peaks separated by a factor of 40. This behaviour can be interpreted as the action of the "propeller regime" of accretion. The onset of the propeller in a 1.37 s pulsar at luminosity of ~$10^{40}$ erg/s implies the dipole component of the neutron star magnetic field of ~$10^{14}$ G.