Browse Topic: Propellers and rotors
This document provides the specifications of horizontal hard-bearing balancing machines, which make such machines suitable for gas turbine rotor balancing
The modern luxurious electric vehicle (EV) demands high torque and high-speed requirements with increased range. Fulfilling these requirements gives rise to the need for increased efficiency and power density of the motors in the Electric Drive Unit (EDU). Internal Permanent Magnet (IPM) motor is one of the best suited options in such scenarios because of its primary advantages of higher efficiency and precise control over torque and speed. In the IPM motor, permanent magnets are mounted within the rotor body to produce a resultant rotating magnetic field with the 3-phase AC current supply in the stator. IPM configuration provides structural integrity and high dynamic performance as the magnets are inserted within the rotor body. Adhesive glue is used to install the magnets within the laminated stack of rotor. High rotational speed of rotor introduces centrifugal loading on the magnets which can result in multiple failure modes such as the debonding of the magnet, and high radial
Additive manufacturing (AM) is currently the most sought-after production process for any complex shaped geometries commonly encountered in Aerospace Industries. Although, several technologies of AM do exits, the most popular one is the Direct Metal Laser Sintering (DMLS) owing to its high versatility in terms of precision of geometries of components and guarantee of highest levels of reduction in production time. Further, metallic component of any complex shape such as Gas Turbine Blades can also be developed by this technique. In the light of the above, the present work focuses on development of iron silicon carbide (Fe-SiC) complex part for ball screw assembly using DMLS technique. The optimized process parameters, hardness and wear resistance of the developed iron-SiC composite will be reported. Further, since the material chosen is a metallic composite one, the effect of SiC on the thermal stresses generated during the DMLS processing of Fe-SiC composite will also be discussed. A
CFM International Cincinnati, OH 513-552-3272
Brake squeal is a common phenomenon across all types of vehicles. It becomes prominent in the absence of other noise sources, as in the case of electric vehicles. Earlier simulation attempts date back to late nineties and early 2000s. Identification of unstable modes of the coupled system of brake rotor and pads, and occasionally some caliper components, was the primary goal. Simulating the rotation of the rotor along with squeezing of the pads was attempted in a multi-body dynamics tools with flexible representation of rotor and pads. Though this gave some insights into the dynamics of stopping mechanism, squeal required capturing the nonlinearities of the contact in a more rigorous sense. Also, efforts were made to capture noise from vibrations using boundary- and finite- element methods [1]. In this attempt at digitalizing a brake dynamometer, the author used a nonlinear implicit solver to mimic the dynamics and transient vibro-acoustic solver to convert transient vibrations to
During validation of a new brake lining on a light duty truck application, the brake rotor exhibited high lateral runout on the friction surfaces. As the engineering team investigated the issue more carefully, they noticed the rotor lateral runout was also changing from revolution to revolution. The team ran testing on multiple light pickup vehicles and found differences in the amount of rotor runout variation. The rotor lateral runout and runout variation can cause vibration and pulsation of the passenger seat and the steering wheel. To identify the root cause of the high level of rotor lateral runout and runout variation, measurement data was collected and analyzed from the vehicle level test. During further analysis, some of the runout variation corresponded to a wheel bearing internal frequency. The bearing internal geometry was studied to confirm what factors affected the runout variation. The team also conducted testing to see how the mating components may have affected the wheel
Electrification is seen as having an important role to play in the fossil-free aviation of tomorrow. But the more energy-efficient an electric aircraft is, the noisier its propellers get. Now, researchers at Chalmers University of Technology have developed a propeller design optimization method that paves the way for quiet, efficient electric aviation
This SAE Aerospace Information Report (AIR) defines the helicopter bleed air requirements which may be obtained through compressor extraction and is intended as a guide to engine designers
Turboprop aircraft have the capability of reversing thrust to provide extra stopping power during landing. Reverse thrust helps save the wear and tear on the brakes and reduces the landing distance under various conditions. The article explains a methodology to predict the disking drag (reverse thrust) from the Computational Fluid Dynamics (CFD) technique using Blade Element Momentum (BEM) theory and estimation of the same from high-speed taxiing trial (HSTT) and ground roll data for a turboprop aircraft using system identification techniques. One-dimensional kinematic equation was used for modeling the aircraft dynamics, and the error between measured and estimated responses was optimized using the Output Error Optimization Method (OEOM). The estimated propeller drag was matched with CFD predictions to arrive at a relation between the propeller blade pitch angle and throttle position. The present study also investigates the estimation of the braking friction coefficient from the
This SAE Aerospace Recommended Practice (ARP) provides a guide for the preparation of a helicopter engine/airframe interface document and checklist. This document and checklist should identify the information needed by the engine manufacturer and the aircraft manufacturer to integrate the engine design with the aircraft design and either provide this information or give reference to where this information is located. The intent is to assure that the engine manufacturer and the airframe manufacturer identify and make provision for this information so it can be easily accessible to either manufacturer as needed in the development stages of an engine-airframe integration project. A related document, SAE Aerospace Information Report AIR6181, provides guidance on creating an interface control document (ICD) which addresses a subset of the aircraft-engine interface information concerning the physical and functional interfaces of the electronic engine control system (EECS) with the aircraft
Titan, Saturn’s largest moon and the only celestial body which is found to have a landmass composed of liquid hydrocarbons. Nitrogen - The building block of all life that exists on earth is found to be abundant in Titan’s atmosphere of up to 97%. Aerobots provide a great platform for exploring a celestial body with an atmosphere such as Titan. They have modest power requirements, longer mission duration, and can cover a longer distance in a shorter time. They are powered by a Radioisotope Thermoelectric Generator for optimal mission life. Aerobot’s altitude can be altered by varying the temperature of the air inside the balloon and yaw can be controlled using a Reaction Wheel and a motor-driven propeller for forwarding thrust. The proposed Aerobot will be equipped with four miniature deployable fixed weather stations that can be dropped from the aerobot to Titan's surface. They can be deployed at diverse locations such as the equator and Polar Regions to deeply explore the Titan’s
This research evaluates the entanglement of an unmanned underwater vehicle (UUV) operating in marine vegetation common to littoral environments. Entanglement was assessed for a traditional UUV with an open, three-bladed propeller transiting a vegetation field at a constant heading and depth. Factors such as the vegetation density, vegetation placement and configuration, propeller revolutions per minute (RPM), and vehicle speed were varied to determine their impact on vehicle entanglement. Results provide insight to the mechanism of entanglement and operating conditions that result in a high or low likelihood of entanglement. These results are of particular interest to the Department of Defense as the military's use of UUVs in littoral environments becomes more prevalent
In this article, we study the problem of axial and radial coupling rub-impact faults based on a full degree-of-freedom rotor system, which has not been extensively discussed in previous literature. An improved magnetorheological (MR) damper configuration is proposed in order to study its effect on the inhibition of coupling rub-impact faults. The Lagrange method is used to establish the finite element model of a rotor-bearing system under radial, axial, and radial-axial coupling rub-impact. At the same time, based on the bilinear constitutive equation of the MR fluid, the dynamic model of the MR damper is established. Through using the Newmark-β method to present a numerical solution, the nonlinear dynamic behaviors of the rotor system under different rub-impact faults are studied; also, the influence of the MR damper on the rub-impact fault dynamic behavior is investigated. The results show that the radial rub-impact makes the system produce rich dynamic behaviors such as period-2 and
Slowed rotors – traditionally associated with autogyros and gyroplanes – have long been recognized as one potential solution for high-speed helicopters (200-300 knots). During the 1950s–70s, there were several significant programs that led to the development of high-speed helicopters with thrust and lift compounding. The key technology barriers common to all were extremely high fuel consumption due to high advancing side drag and large reverse flow, complexities associated with RPM reduction, large blade motions during RPM reduction, and unexplained but catastrophic aeroelastic instabilities of rigid rotors (Cheyenne). None of these helicopters entered regular production
Items per page:
50
1 – 50 of 812