An innovative design of a supersonic ROTOR pressure-exchange ejector is introduced in this paper. In this design, momentum is exchanged between supersonic primary flow and secondary flow using an idle ROTOR. A CFD code developed to model the 3-D compressible, viscous and turbulent flow of air inside the new design of ejector. Roe approach and Spallart-Allmaras methods used to analyze flow inside the ejector. The flow inside the ejector was modeled by using a structured grid and air was employed as the working fluid in both primary and secondary streams. The Mach number of the motive flow was set at 2. Momentum exchanged between the primary and secondary flows because of direct contact between those. In addition to that, rotation of idle ROTOR and mechanical blades entrained the secondary flow to the ejector. Enthalpy, entrained mass flow rate and created vacuum presented for the flow inside the ejector for different configurations of the ROTOR and ejector until an optimum case was achieved. Also, uniformity of the flow at discharge section compared between ejectors. For the optimum case with the presented geometry, the ultimate ROTOR speed of 50000 rpm was obtained and an increase of 47% in entrainment ratio achieved with respect to the stationary blades. To study the flow field in more details, the contours of the Mach number and stagnation pressure were compared according to the different sections of computational domain.

Airborne wind energy system (AWES) is a novel approach in wind energy harvesting. It has several advantages against conventional horizontal axis wind turbine (HAWT), like using less material and thus lower manufacturing cost, higher efficiency, stable electricity output and higher capacity for energy harvesting. It is obviously embedding a complex control system which makes the appropriate flight trajectory for the vehicle. These systems need to be carefully designed so using virtual flight simulators in design process is crucial. The main components of a typical AWES are: tether, flyer, and ROTORs. The flyer is designed to have a tether-constrained flight across the wind in a circular path. Consequently, the mounted ROTORs on the flyer’s wings will capture energy and this mechanical/electrical energy would be sent back to the ground via the same tether. It is notable that the flight path and the special design of the flyer, would make it capable to have a sustained motion in the circular loop with no energy consumption. A tethered drone equipped with several ROTORs is an example of such devices, already has been built and tested. In previous literature, the flight simulators usually contain some simple aerodynamic models for predicting the forces and moments generated by the ROTORs. It is derived by constant aerodynamic coefficients. In the current study, it has been developed a flight simulator for a typical AWES having onboard ROTORs. To make this flight simulator more accurate and to improve its fidelity in different environmental conditions, proper estimation of the external forces, particularly the aerodynamic forces and moments, seems to be necessary. Therefore, toward developing a high-fidelity simulator, Lagrangian DYNAMICS and a new algorithm for estimation of the ROTOR aeroDYNAMICS, has been utilized. This new method is shown to have more accurate approximations of the system performance and also better description of the vehicle trajectory. By this framework, one could design optimized blades of the ROTORs and also the ROTORs arrangement. Implementing the new simulator, a single drone, as the flyer in AWES, having 3m wing span, would experience 40 percent improvement in the average power extracted which is near 2 KW.

The helicopter ROTOR blade flapping results in a helicopter ROTOR symmetry lift and has a significant impact on stability and control. In this paper, the modeling of helicopter flapping in the presence of aerodynamic forces and moments and the effect of offset, blade torque, hinge resistant spring, blade geometry, natural frequency effect, and forward ratio to achieve reliable relief from flapping was investigated. In the simulation, the effects of small and large flapping angles and the role of offset on the momentum entered on the blade, as well as the role of the forward ratio in moments were investigated. Different models of flapping DYNAMICS and equations for the flight of a hover and cruise helicopter are fully presented and all of the important issues are examined for a numerical example. Also, the effect of non-uniform flow in the flapping equations of the blade is the effect of the natural frequency of the flapping motion with the blade offset. This leads to increasing the accuracy in modeling the phenomenon of flapping on a helicopter. Simulation results show the importance and impact of offsets, moments and forces imposed on the blade in the motion of the flapping, which leads to an increase of accuracy in modeling.

In the present study, the effect of stator DYNAMICS on the chaotic behavior of a ROTOR-diskbearing system with rub-impact between disk and stator is investigated. The governing equations of motion are derived using Jeffcott model and Newton’s second law and then are made dimensionless. In the beginning, the system is modeled regardless of stator DYNAMICS, and then the stator DYNAMICS is also considered in the modeling of the system. In both cases, the system behavior is studied by bifurcation diagrams, time series diagrams, phase plane diagrams, power spectrum diagrams, Poincaré maps, and maximum Lyapunov exponent, respectively. The obtained results show that the type of stator DYNAMICS modeling has a significant effect on the prediction of the response of a disk-bearing system with rubimpact between disk and stator. In other words, the results show the system has a chaotic behavior without considering the DYNAMICS of the stator in mathematical modeling, while in the case of considering the stator DYNAMICS and using the suitable values for the stator stiffness, the motion behavior of the system can be changed from the chaotic to the regular and periodic motion.

The Counter-Rotating Fan (CRF) offers higher aerodynamic performance, in terms of pressure head and aerodynamic efficiency, compared to the single ROTOR fan, thus making it an attractive solution for equipment cooling and ventilation of mines and tunnels. Nevertheless, further investigations are required to understand the flow interactions between the front ROTOR (FR) and the rear ROTOR (RR), as these interactions are sources of noise emission. This numerical study used the Unsteady Reynolds Average Navier-Stokes (URANS) flow simulations and the Fast Fourier transformation (FFT) to analyse the ROTOR-ROTOR interactions and consequences on the aero-acoustic performance. The static pressure fluctuations were recorded at several locations and analysed by FFT to reveal the mechanisms of flow interactions and the effects of axial inter-distance between the two ROTORs. The inter-distance seems to influence the aerodynamic loading of RR more than that of FR and the total-to-static isentropic efficiency tends to drop. Over one chord distance, the noise level decreases but at the expense of isentropic efficiency. The balanced performance does not seem to improve for an inter-distance greater than 1. 5 chords, considered the optimum distance in this study. Finally, a graphical correlation which can be used to estimate the Sound Pressure Level (SPL) is developed for this category of CRF.

Turbochargers are most widely used in automotive, marine and locomotive applications with diesel engines. To increase the engine performance nowadays, in aerospace applications also turbochargers are used. Mostly the turbocharger ROTORs are supported over the fluid film bearings. With the operation, lubricant properties continuously alter leading to different load bearing capacities. This paper deals with the diagnostic approach for prediction of shaft unbalance and the bearing parameters using the measured frequency responses at the bearing locations. After validating the natural frequencies of the ROTOR finite element model with experimental analysis, the response histories of the ROTOR are recorded. The influence of the parameters such as bearing clearance, oil viscosity and casing stiffness on the unbalance response is studied. By considering three levels each for shaft unbalance and oil viscosity, the output data in terms of four statistical parameters of equivalent Hilbert envelopes in the frequency domain are measured. The data are inversely trained using Radial Basis Function (RBF) neural network model to predict the unbalance and oil viscosity indices from given output response characteristics. The outputs of the RBF model are validated thoroughly. This approach finds changes in the ROTOR bearing parameters from the measured responses in a dynamic manner. The results indicate that there is an appreciable effect of lubricant viscosity at two different temperatures compared to other parameters within the operating speed range. The identification methodology using the neural network is quite fast and reliable.

In this research the effect of combing process on physical and mechanical properties of cotton ROTOR yams and the fabrics woven from these yams is studied. Also, the effect of ROTOR diameter and combination of ROTOR diameter and ROTOR groove angle on the yam properties are studied. For this purpose, combed and carded ROTOR yams were produced with the count of 30Ne from a blend of 4 types of cotton and then were used in woven fabrics construction as weft yam.The results show that combing process reduces the CV% of yarns and improves the strength. It also decreases the twist insertion ratio and hairiness of yams. The dye absorption of combed yams is better than the carded one.It was also seen that the strength, bending and abrasion resistance of fabrics woven from combed yams is more than carded yarns, but the drape is less. Furthermore, It was considered that the air permeability of fabrics woven from combed yams is higher than carded ones. The statistical t-student tests were carried out in 95% confidence interval by using SPSS 9.0 software to evaluate the combed and carded yarn properties. The obtained results confirm the statistical difference between the produced yarn and fabric samples of combed and carded ROTOR yarns.

The scope of this paper is to consider two-dimensional flows in a ROTOR-stator blade rows and to analyze their effects on each other. The control volume approach based on Jameson's technique is used to solve two-dimensional unsteady compressible Euler equations in a stage of an axial flow turbine. The computational speed. At the intersection of the domains, a slip grid technique is used. The equations are solved simultaneously for both domains. The method is used in this paper for slipping of the grid has some advantages over the other slipping techniques with regard to the accuracy and CUP time. In this technique, transferring the information from the moving mesh to the stationary mesh is done by using some imaginary cells. The cubic spline interpolation is employed in such a way that the conservation laws to be satisfied. The results obtained for an axial flow turbine in this work, are compared with other's results and good agreement is obtained. Finally, the effects of row spacing between the stator and ROTOR blades are considered and analyzed.

In this paper, the nonlinear vibration behavior of a ROTOR with asymmetric shaft considering misalignment is studied. The system consists of a rectangular shaft and a disk, which is connected to a motor through a flexible coupling. In order to consider higher order deformations, nonlinear Bernoulli beam is used for modeling the shaft. Gibbons’ equations are utilized to apply misaligned coupling forces. The equations of motion of the system are derived using the Lagrangian method and then discretized by the Rayleigh-Ritz method. In order to solve nonlinear equations and hence obtaining nonlinear responses, multiple scales method is used. The vibration behavior of the system near the resonance frequencies is studied by taking into account various parameters including unbalance forces and the effect of the asymmetry of cross section of the shaft. The analytical results are consistent with those of numerical method with a good accuracy. In addition, the effects of variations of the system parameters on the ROTOR vibration behavior have been shown graphically. In the end, the changes in the various parameters of the system and their effects on the ROTOR vibration response are discussed.

Wound ROTOR induction machine (WRIM) has been extensively used in different applications such as medium-power wind turbines and traction systems. Since these machines work under harsh and difficult conditions, condition monitoring of such systems is crucial. Different electrical and mechanical signatures of machines were used for electrical and mechanical fault detection in electrical machines such as vibration, acoustic emission, stray flux, and stator current signature. In recent years, stator current signature analysis due to simplicity, cost-effectiveness, and availability has been considered for fault detection process in comparison with previous conventional methods such as acoustic and vibration. In this paper, a high-resolution technique based on the chirp-Z transform is used for ROTOR asymmetry fault (RAF) detection in induction machines through stator current signature analysis. In this regard, the Teager-Kaiser energy operator (TKEO) technique for demodulation fault characteristic frequency is used as a pre-processing stage to avoid leakage of the supply frequency. The method has better accuracy due to better spectral resolution and resolvability. Furthermore, computational complexity in the proposed method will be reduced in comparison to the previous conventional ones which have used the Fast Fourier transform (FFT). The proposed technique is tested through synthetic and experimental stator current of WRIM in healthy and faulty conditions with different rotational speeds and fault severities. The results show the validity of the proposed method in ROTOR asymmetry fault detection through the stator current signature of WRIM.