Browse Topic: Stall
Regular readers of Supplier Eye will note that this author tries to outline the positives and the negatives of supplier strategies. It's a moving target. A recent deluge of negative headlines with respect to EVs has OEMs, suppliers and other participants re-evaluating their strategies. Slower consumer acceptance and stalled sales of some EVs - in combination with the recent eye-popping labor agreements with the UAW and Unifor unions - underscore that return on capital and labor-cost challenges will be core considerations going forward. At no point was this transition going to be smooth - “lumpy” is a better description. While there are several positives with the ICE-to-EV transition (emissions, efficiency, reduction of carbon-fuel dependence and running costs), there are hurdles that cannot be dismissed. Of late, several of these concerns have become more prominent. One surrounds the ability for government and industry to effectively bridge the higher costs (due to scale economies) of
Passengers would always like to reach their destinations with minimum commute time. Generating a higher thrust is a necessity. This implies that the turbomachinery associated with the power plant has to rotate faster and with higher efficiencies. However, high rotational speeds, mainly in the transonic regime, often lead to boundary layer separation, shocks, compressor stall, and surge. The current investigation is an attempt to reduce the abovementioned phenomena. It involves the performance study of a smoothened controlled diffusion airfoil (CDA) blade that has been optimized by “Multi-Objective Genetic Algorithm” (MOGA) by altering maximum camber location and stagger angle. Inlet pressure is varied from 15 kPa to 30 kPa and the angle of attack ranging from 40.4° to 56.4°. C48-S16-BS1 is validated and considered as the baseline profile, and all other blades are collated to this. It is observed that shifting the location of the maximum camber close to the leading edge and increasing
Dual mass flywheel (DMF) is an excellent solution to improve the noise, vibration and harshness (NVH) characteristic of any vehicle by isolating the driveline from the engine torsional vibrations. For the same reason, DMFs are widely used in high power-density diesel and gasoline engines. However, the real-world usage conditions pose a lot of challenges to the structural robustness of the DMF. In the present work, a new methodology is developed to evaluate the robustness of a DMF fitted in a compact sports utility vehicle (SUV) with rear-wheel drive architecture. The abuse conditions (mis-gear, sudden braking, etc) in the real-world usage could lead to a sudden engine stall leading to an abnormally high angular deceleration of the driveline components. The higher rate of deceleration coupled with the higher rotational moment of inertia of the systems might end up in introducing a significantly high impact torque on the DMF. Hence, prolonged usage of the vehicle in abuse conditions
The present work is focussed on the real-world challenges of a dual mass flywheel (DMF) equipped vehicle in the Indian market. DMFs are widely used to isolate the drivetrain from the high torsional vibrations induced by the engine. While DMFs can significantly improve noise, vibration and harshness (NVH) characteristics of a vehicle, there are multiple challenges experienced in real-world operating conditions when compared with the single mass flywheel (SMF). The present work explains the challenges of using a DMF in a high power-density diesel powertrain for a multi-purpose vehicle (MPV) application in the Indian market. Measurements on the flat-road operating conditions revealed that the DMF vehicle is very sensitive for launch behaviour and requires a higher clutch modulation. Vibration measurements at the driver’s seat confirm that the SMF vehicle could be launched more comfortably at the engine idle speed of 850 RPM. However, the DMF vehicle needs a "launch assist" of an
Since the torque converter and fluid coupling are commonly used components of automatic transmissions in industry, the SAE appointed a committee to standardize terminology, test procedure, data recording, design symbols, and so forth, in this field. The following committee recommendations will facilitate a clear understanding for engineering discussions, comparisons, and the preparation of technical papers. The recommended usages represent the predominant practice or the acceptable practice. Where agreement is not complete, alternates have been included for clarification. EXAMPLE: Two systems of blade angle designations are described. Consequently, when a blade angle is specified, the system should be designated. This SAE Recommended Practice deals only with the physical parts and dimensions and does not attempt to standardize the design considerations, such as the actual fluid flow angle resulting from the physical blade shape
This test code describes tests for determining characteristics of hydraulic positive displacement motors as used on off-road self-propelled work machines as referenced in SAE J1116
This paper presents a coupled numerical and experimental study of an unconventional wing profile such as cp-180-050-gn (Cambered plate C = 18% T = 5% R = 0.78). This wing profile deals with low speeds. It is not currently used on any aircraft model. Otherwise, it presents interesting performances that can be exploited for the design of low-speed STOL or VTOL aircraft by mean of the very high lift that it can generate and can fit with different uses such as VAWT, cyclorotors drones, which are designed explicitly for low-speed operations. After a preliminary CFD assessment of the wing a complete experimental characterisation also at high angles of attack has been performed. The excellent agreement between CFD and experiments has allowed producing a complete analysis of the behaviour of the wing profile both before and after stall conditions. This study has the objective of analysing the viability of such an unconventional wing in traditional or over-stalling conditions. A complete
Cars in several motor sports series, such as Formula 1, make use of multi-element front wings to provide downforce. These wings also provide onset flows to other surfaces that generate downforce. These elements are highly loaded to maximise their performance and are generally operating close to stall. Rubber debris, often known as marbles, created from the high slip experienced by the soft compound tyres can become lodged in the multiple elements of a front wing. This will lead to a reduction in the effectiveness of the wing over the course of a race. This work will study the effect of such debris, both experimentally and numerically, on an inverted double element wing in ground effect at representative Reynolds numbers. The wing was mounted at two different ride heights above a fixed false-floor in the Loughborough University wind tunnel and the effect of debris blockage modelled by closing sections of the gap between elements with tape. The reduction in downforce compared to the
This recommendation establishes objectives for high performance control motors to be used with aeronautical and associated equipment in protective enclosures or completely within the shell of the aircraft so that they are subjected only to the internal climatic conditions of heat, cold, shock, vibration, altitude, and humidity. Control motors larger than size #23 are not covered in this document
The scope of this SAE Aerospace Information Report (AIR) is to present a guide for the determination of probable power output and the effect on the aircraft system that will be experienced when operating three-phase motors with one phase open. Unfortunately, the above subject cannot be resolved by specific rules. Modern aircraft or missile electrical systems are composed of a wide variety of electrical and electronic components. These components react differently under identical impetus due to the latitude of their design. This latitude of design must be allowed wherever possible to the accessory designer due to the various specification requirements. Therefore, it cannot be over-emphasized that the effect on the airplane or missile system, as well as motor operation, of three-phase motors on two-phase power must be thoroughly investigated
This SAE Aerospace Recommended Practice (ARP) defines minimum requirements for an aircraft transport ULD to transport horses properly and safely by air, to protect the horse(s) from injuries, and to protect the aircraft from corrosion created by waste spill. The ULD is designed to accommodate one horse or several. There are two types of ULDs for aircraft transportation of horses
The main objective of this research was to better understand the flow physics of aircraft wings undergoing highly unsteady maneuvers. Reduced-order models play a central role in this study, both to elucidate the overall dynamical mechanisms behind various flow phenomena (such as dynamic stall and vortex shedding), and ultimately to guide flight control design for vehicles for which these unsteady phenomena are important
As the cost and complexity of modern aircraft systems increases, emphasis has been placed on model-based design as a means for reducing development cost and optimizing performance. To facilitate this, an appropriate modeling environment is required that allows developers to rapidly explore a wider design space than can cost effectively be considered through hardware construction and testing. This wide design space can then yield solutions that are far more energy efficient than previous generation designs. In addition, non-intuitive cross-coupled subsystem behavior can also be explored to ensure integrated system stability prior to hardware fabrication and testing. In recent years, optimization of control strategies between coupled subsystems has necessitated the understanding of the integrated system dynamics. To this end, a dynamic vapor cycle modeling toolset known as the AFRL Transient Thermal Management and Optimization (ATTMO) toolset was developed to address two-phase flow
The Learjet 85 is a business jet with an unpowered manual elevator control and is designed for a maximum dive Mach number of 0.89. During the early design, it was found that the stick force required for a 1.5g pull-up from a dive would exceed the limit set by FAA regulations. A design improvement of the tailplane was initiated, using 2D and 3D Navier-Stokes CFD codes. It was discovered that a small amount of positive camber could reduce the elevator hinge moment for the same tail download at high Mach numbers. This was the result of the stabilizer forebody carrying more of the tail download and the elevator carrying less. Consequently, the elevator hinge-moment during recovery from a high-speed dive was lower than for the original tail. Horizontal tails are conventionally designed with zero or negative camber since a positive camber can have adverse effects on tail stall and drag. The tailplane sections for the Learjet 85 were tailored to minimize these adverse effects while achieving
The innovative highly flexible wings made of extremely light structures, yet still capable of carrying a considerable amount of non- structural weights, requires significant effort in structural simulations. The complexity involved in such design demands for simplified mathematical tools based on appropriate nonlinear structural schemes combined with reduced order models capable of predicting accurately their aero-structural behaviour. The model presented in this paper is based on a consistent nonlinear beam-wise scheme, capable of simulating the unconventional aeroelastic behaviour of flexible composite wings. The partial differential equations describing the wing dynamics are expanded up to the third order and can be used to explore the effect of static deflection imposed by external trim, the effect of gust loads and the one of nonlinear aerodynamic stall. As to provide a rationale evaluation of the important nonlinear contributions in aeroelastic wing simulations, the aeroelastic
Flow control over aerodynamic shapes in order to achieve performance enhancements has been a lively research area for last two decades. Synthetic Jet Actuators (SJAs) are devices able to interact actively with the flow around their hosting structure by providing ejection and suction of fluid from the enclosed cavity containing a piezo-electric oscillating membrane through dedicated orifices. The research presented in this paper concerns the implementation of zero-net-mass-flux SJAs airflow control system on a NACA0015, low aspect ratio wing section prototype. Two arrays with each 10 custom-made SJAs, installed at 10% and 65% of the chord length, make up the actuation system. The sensing system consists of eleven acoustic pressure transducers distributed in the wing upper surface and on the flap, an accelerometer placed in proximity of the wing c.g. and a six-axis force balance for integral load measurement. A dSPACE™ hardware connected to the software environment Matlab/Simulink® and
This SAE Aerospace Recommended Practice (ARP) defines minimum requirements for an aircraft transport ULD to transport horses properly and safely by air, to protect the horse(s) from injuries, and to protect the aircraft from corrosion created by waste spill. The ULD is designed to accommodate one horse or several. There are two types of ULDs for aircraft transportation of horses: a Type 1: The ULD is an airworthiness certified structural container, satisfying the requirements of NAS 3610 for the appropriate base size. b Type 2: The ULD consists of a self-contained stall which is positioned on a standard aircraft pallet and restrained to the pallet by means of a cargo pallet net or by straps. WARNING: It is the carrier’s responsibility to obtain airworthiness approval for a Type 2 unit using strap-restraint. Refer to 7.1 b (Documentation
A stall prediction method based on unsteady hinge moment measurements was previously developed from experimental hinge moment measurements on a NACA 3415 airfoil model under a clean configuration and four iced configurations. The stall prediction algorithm was based on three separate detector functions. Additional hinge moment measurements have been obtained experimentally for a NACA 23012 airfoil model, using these same clean and iced configurations. Tests were also conducted with boundary-layer trips on the model upper and lower surfaces. The addition of simulated icing degraded the performance of the NACA 23012. Upon application of the hinge moment stall prediction method, two of the six configurations provided detector function outputs that were inconsistent with the other four configurations. Further investigation revealed differences in the hinge moment signal between contamination configurations due to the presence of different types and extents of primary stall mechanisms
In this article, a methodology for flight tests to determine the stall speed is adapted for UAVs (unmanned aerial vehicles). The UAV is equipped with a system of data acquisition to store the variables related to the stall speed during the flight of the aircraft. Next the data is processed to determine the stall characteristics of the aircraft and consequently its stall speed. The results are compared with analytical calculations to validate the proposed methodology
The scope of this SAE Aerospace Information Report (AIR) is to present a guide for the determination of probable power output and the effect on the aircraft system that will be experienced when operating three-phase motors with one phase open. Unfortunately, the above subject cannot be resolved by specific rules. Modern aircraft or missile electrical systems are composed of a wide variety of electrical and electronic components. These components react differently under identical impetus due to the latitude of their design. This latitude of design must be allowed wherever possible to the accessory designer due to the various specification requirements. Therefore, it cannot be over-emphasized that the effect on the airplane or missile system, as well as motor operation, of three-phase motors on two-phase power must be thoroughly investigated
This recommendation establishes objectives for high performance control motors to be used with aeronautical and associated equipment in protective enclosures or completely within the shell of the aircraft so that they are subjected only to the internal climatic conditions of heat, cold, shock, vibration, altitude, and humidity. Control motors larger than size #23 are not covered in this document
This test code describes tests for determining characteristics of hydraulic positive displacement motors as used on construction and industrial machinery as referenced in SAE J1116. These characteristics are to be recorded on data sheets similar to the one shown in Figure 1. Two sets of data sheets are to be submitted: one at 49 °C (120 °F) and one at 82 °C (180 °F
The Traction Control Systems (TCS) for the FSAE car were developed with the Fuel/Ignition Cut (FIC) method and the Ignition Retard (IR) method. A slip speed was used for the TCSs and a custom Engine Control Unit (KF-ECU07) was developed with commercial devices. With the FIC TCS, the engine was stalled and the IR TCS worked better. KF-ECU07 was 7.6% of the commercial high-quality ECU in price and contributed to the cost event point gain in FSAE. The driver load was evaluated with the duration ratio of the partial throttle aperture. The duration ratio of the partial throttle aperture was 52% with the IR-TCS compared with 64% without IR-TCS and 19% driver load was decreased
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