scholarly journals Design of distributed propulsion system for general aviation airplane

2019 ◽  
Vol 304 ◽  
pp. 03009
Author(s):  
Pavel Hospodář ◽  
Jan Klesa ◽  
Nikola Žižkovský
Keyword(s):  
Combustion Engine ◽  
Dynamic Pressure ◽  
Design Procedure ◽  
Leading Edge ◽  
General Aviation ◽  
Local Dynamic ◽  
Wing Area ◽  
Sufficient Power ◽  
Distributed Propulsion ◽  
Electrical Propulsion

In this paper, a small airplane is redesigned by using a distributed electrical propulsion (DEP) system. The design procedure is focused on the reduction of fuel consumption in cruise regime with constrained parameters of take-off/landing. In this case, a one half wing area compared to an original airplane is used. Take-off distance and minimum airspeed for landing is achieved by distributed propellers mounted on the leading edge of the wing. These propellers induce velocity on the wing and thereby increase local dynamic pressure, thus the required lift force can be reached with smaller wing area. Moreover, the distributed propellers are assumed as folded in cruise regime to minimize drag when the main combustion engine provides sufficient power.

scholarly journals Towards higher aerodynamic efficiency of propeller-driven aircraft with distributed propulsion

2021 ◽  
Author(s):  
Dennis Keller
Keyword(s):  
Performance Indicator ◽  
Leading Edge ◽  
Substantial Improvement ◽  
Initial Assessment ◽  
Local Flow ◽  
Propulsive Efficiency ◽  
Thrust Distribution ◽  
Distributed Propulsion ◽  
Wing Tip ◽  
Cruise Flight

AbstractThe scope of the present paper is to assess the potential of distributed propulsion for a regional aircraft regarding aero-propulsive efficiency. Several sensitivities such as the effect of wingtip propellers, thrust distribution, and shape modifications are investigated based on a configuration with 12 propulsors. Furthermore, an initial assessment of the high-lift performance is undertaken in order to estimate potential wing sizing effects. The performance of the main wing and the propellers are thereby equally considered with the required power being the overall performance indicator. The results indicate that distributed propulsion is not necessarily beneficial regarding the aero-propulsive efficiency in cruise flight. However, the use of wing tip propellers, optimization of the thrust distribution, and wing resizing effects lead to a reduction in required propulsive power by $$-2.9$$ - 2.9 to $$-3.3\,\%$$ - 3.3 % compared to a configuration with two propulsors. Adapting the leading edge to the local flow conditions did not show any substantial improvement in cruise configuration to date.

Inflight icing data gathering during routine flight operations — a case study

2001 ◽  
Vol 105 (1051) ◽  
pp. 501-516 ◽  
Author(s):  
A. P. Brown
Keyword(s):  
Data Gathering ◽  
Winter Season ◽  
Leading Edge ◽  
General Aviation ◽  
Data Sets ◽  
Large Droplet ◽  
Event Data ◽  
Flight Operations ◽  
Lower Corner

Abstract For the purpose of the design and certification of inflight icing protection systems for transport and general aviation aircraft, the eventual re-definition/expansion of the icing environment of FAR 25/JAR 25, Appendix C is under consideration. Such a re-definition will be aided by gathering as much inflight icing event data as reasonably possible, from widely-different geographic locations. The results of a 12-month pilot programme of icing event data gathering are presented. Using non-instrumented turboprop aircraft flying upon mid-altitude routine air transport operations, the programme has gathered observational data from across the British Isles and central France. By observing a number of metrics, notably windscreen lower-corner ice impingement limits, against an opposing corner vortex-flow, supported by wing leading edge impingement limits, the observed icing events have been classified as ‘small’, ‘medium’ or ‘large’ droplet. Using the guidance of droplet trajectory modelling, MVD values for the three droplet size bins have been conjectured to be 15, 40 and 80mm. Hence, the ‘large’ droplet category would be in exceedance of FAR/JAR 25, Appendix C. Data sets of 117 winter-season and 55 summer-season icing events have been statistically analysed. As defined above, the data sets include 11 winter and five summer large droplet icing encounters. Icing events included ‘sandpaper’ icing from short-duration ‘large’ droplets, and a singular ridge formation icing event in ‘large’ droplet. The frequency of ‘large’ droplet icing events amounted to 1 in 20 flight hours in winter and 1 in 35 flight hours in summer. These figures reflect ‘large’ droplet icing encounter probabilities perhaps substantially greater than previously considered. The ‘large’ droplet events were quite localised, mean scale-size being about 6nm.

Generation Mechanism of Broadband Whoosh Noise in an Automotive Turbocharger Centrifugal Compressor

2021 ◽  
pp. 1-35
Author(s):  
Rick Dehner ◽  
Pranav Sriganesh ◽  
Ahmet Selamet ◽  
Keith Miazgowicz
Keyword(s):  
Centrifugal Compressor ◽  
Combustion Engine ◽  
Three Dimensional ◽  
Leading Edge ◽  
Broadband Noise ◽  
Rotor Blades ◽  
Generation Mechanism ◽  
Primary Concern ◽  
Frequency Range ◽  
Modal Decomposition

Abstract The present study focuses on the acoustics of a turbocharger centrifugal compressor from a spark-ignition internal combustion engine. Whoosh noise is typically the primary concern for this type of compressor, which is loosely characterized by broadband sound elevation in the 4 to 13 kHz range. To identify the generation mechanism of broadband whoosh noise, the present study combines three approaches: three-dimensional (3D) computational fluid dynamics (CFD) predictions, experiments, and modal decomposition of 3D CFD results. After establishing the accuracy of predictions, flow structures and time-resolved pressures are closely examined in the vicinity of the main blade leading edge. This reveals the presence of rotating instabilities that may interact with the rotor blades to generate noise. An azimuthal modal decomposition is performed on the predicted pressure field to determine the number of cells and the frequency content of these rotating instabilities. The strength of the rotating instabilities and the frequency range in which noise is generated as a consequence of the rotor-rotating instability interaction, is found to correspond well with the qualitative trend of the whoosh noise that is measured several duct diameters upstream of the rotor blades. The variation of whoosh frequency range between low and high rotational speeds is interpreted through this analysis. It is also found that the whoosh noise primarily propagates along the duct as acoustic azimuthal modes. Hence, the inlet duct diameter, which governs the cut-off frequency for multi-dimensional acoustic modes, determines the lower frequency bound of the broadband noise.

Wing Mechanics and Take-Off Preparation of Thrips (Thysanoptera)

1980 ◽  
Vol 85 (1) ◽  
pp. 129-136 ◽  
Author(s):  
C. P. ELLINGTON
Keyword(s):  
Leading Edge ◽  
Morphological Features ◽  
Inertial Forces ◽  
Wing Area ◽  
Trailing Edge ◽  
Lateral Projection ◽  
Parking Problem ◽  
Closed Position ◽  
Open Position ◽  
Fringe System

1. All of the wing fringe cilia of Thrips physapus, except those along the hindwing leading edge, pivot in elongated sockets which lock them into two positions. 2. The wings lie parallel over the abdomen when not in use, with the cilia locked in the closed position at an angle of 15-20° to the wing axis. The closing of the fringes prevents entanglement of the trailing edge cilia and lateral projection of the forewing leading edge cilia. 3. During flight the cilia are locked in the open position, doubling the wing area. The locking force is stronger than the combined aerodynamic and inertial forces on the cilia. 4. The fringes are opened by abdominal combing and closed by tibial combing. 5. The same morphological features are found in other members of the sub-order Terebrantia. Parallel wings at rest are characteristic of this suborder, and the collapsible fringe system is viewed as an effective method for parking the wings. 6. The fringes of the sub-order Tubulifera are not collapsible. The wings overlap on the abdomen at rest and a similar parking problem does not arise.

scholarly journals Analysis of the Application of Distributed Propulsion to the AOS H2 Motor Glider

2019 ◽  
Vol 26 (2) ◽  
pp. 85-92
Author(s):  
Michał Kuźniar ◽  
Marek Orkisz
Keyword(s):  
Combustion Engine ◽  
Electric Motors ◽  
Flight Duration ◽  
Electric System ◽  
University Of Technology ◽  
Distributed Propulsion ◽  
Small Set ◽  
And Performance ◽  
Fitting In ◽  
Selection Of

Abstract The paper describes the selection of a distributed propulsion for the AOS H2 motor glider (selection of engines, their number, and propellers) and determination of its performance. This analysis is related to the research conducted on environment friendly and hybrid propulsions in various research centres. The main aim of the analyses conducted is to increase the performance of vehicles powered by electric motors. The batteries have a low density of energy, i.e. the ratio of mass to cumulated energy. Instead of a battery set, it is possible to apply a hybrid-electric system, where the combustion engine works as a generator or an electric-hydrogen generator, where the hydrogen cell supports a small set of batteries. One of such flying vehicles, fitting in this trend, is the AOS H2 motor glider built at the Rzeszow University of Technology in cooperation with other universities. It is a hybrid aircraft, equipped with a hydrogen cell, which together with a set of batteries is a source of electricity for the Emrax 268 electric motor. To increase the vehicle's performance (the range and flight duration), it is possible to use a distributed propulsion. This type of propulsion consists in placing many electric motors along the wingspan of the aircraft. Appropriate design of such a system (propeller diameters, engine power, number of engines) can improve the aerodynamic and performance parameters of the airframe. An analysis of the performance for the selected flight trajectory for this propulsion variant was conducted and compared to the performance of the AOS H2 motor glider equipped with traditional propulsion. The consumption of hydrogen was also determined for both systems. The results obtained were presented in the diagrams and discussed in the conclusions.

scholarly journals Unsteady Pressure Measurements on a Biconvex Airfoil in a Transonic Oscillating Cascade

1986 ◽  
Vol 108 (1) ◽  
pp. 53-59 ◽  
Author(s):  
L. M. Shaw ◽  
D. R. Boldman ◽  
A. E. Buggele ◽  
D. H. Buffum
Keyword(s):  
Mach Number ◽  
Incidence Angle ◽  
Dynamic Pressure ◽  
Leading Edge ◽  
Pressure Transducers ◽  
High Incidence ◽  
Shock Motion ◽  
Plate Analysis ◽  
Phase Angles ◽  
Unsteady Pressure Measurements

Flush-mounted dynamic pressure transducers were installed on the center airfoil of a transonic oscillating cascade to measure the unsteady aerodynamic response as nine airfoils were simultaneously driven to provide 1.2 deg of pitching motion about the midchord. Initial tests were performed at an incidence angle of 0.0 deg and a Mach number of 0.65 in order to obtain results in a shock-free compressible flow field. Subsequent tests were performed at an angle of attack of 7.0 deg and a Mach number of 0.80 in order to observe the surface pressure response with an oscillating shock near the leading edge of the airfoil. Results are presented for interblade phase angles of 90 and −90 deg and at blade oscillatory frequencies of 200 and 500 Hz (semichord reduced frequencies up to about 0.5 at a Mach number of 0.80). Results from the zero-incidence cascade are compared with a classical unsteady flat-plate analysis. Flow visualization results depicting the shock motion on the airfoils in the high-incidence cascade are discussed. The airfoil pressure data are tabulated.

Inverse Design and Optimization of a Return Channel for a Multistage Centrifugal Compressor

2004 ◽  
Vol 126 (5) ◽  
pp. 799-806 ◽  
Author(s):  
A´rpa´d Veress ◽  
Rene´ Van den Braembussche
Keyword(s):  
Design Method ◽  
Design Procedure ◽  
Leading Edge ◽  
Secondary Flows ◽  
Inverse Design ◽  
Navier Stokes ◽  
Design And Optimization ◽  
The Cross ◽  
Return Channel ◽  
The Impact

The design and optimization of a multistage radial compressor vaneless diffuser, cross-over and return channel is presented. An analytical design procedure for 3D blades with prescribed load distribution is first described and illustrated by the design of a 3D return channel vane with leading edge upstream of the cross-over. The analysis by means of a 3D Navier–Stokes solver shows a substantial improvement of the return channel performance in comparison with a classical 2D channel. Most of the flow separation inside and downstream of the cross-over could be avoided in this new design. The geometry is further improved by means of a 3D inverse design method to smooth the Mach number distribution along the vanes at hub and shroud. The Navier–Stokes analysis shows a rather modest impact on performance but the calculated velocity distribution indicates a more uniform flow and hence a larger operating range can be expected. The impact of vane lean on secondary flows is investigated and further performance improvements have been obtained with negative lean.

Dynamic Pressure Measurement and Uncertainty Analysis Using a Piezoelectric Transducer for a Combustion Engine

2016 ◽  
Vol 827 ◽  
pp. 77-82 ◽  
Author(s):  
Andrzej Bąkowski ◽  
Leszek Radziszewski ◽  
Milan Žmindák
Keyword(s):  
Pressure Measurement ◽  
Combustion Engine ◽  
Dynamic Pressure ◽  
Type A ◽  
Standard Uncertainty ◽  
Maximum Pressure ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Dynamic Pressure Measurement ◽  
Engine Type

This paper analyses the uncertainty of pressure measurements in-cylinder and in injection pipe conducted during the studies of a compression ignition engine. Type A and type B evaluations were used to determine the uncertainties of the results. The results are presented for the engine running on diesel or bio-fuel and operating under full load conditions. The results of normality tests provide grounds to reject H0 in some cases. Slightly lower standard uncertainty of the maximum pressure measurement calculated using type A evaluation were acquired for the engine running on bio-fuel.

Unsteady Forces of Rotor Blades in Full and Partial Admission Turbines

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Narmin Baagherzadeh Hushmandi ◽  
Jens E. Fridh ◽  
Torsten H. Fransson
Keyword(s):  
Pressure Field ◽  
Dynamic Pressure ◽  
Turbine Blades ◽  
Leading Edge ◽  
Rotational Frequency ◽  
Rotor Blades ◽  
Computational Domain ◽  
Unsteady Forces ◽  
Partial Admission ◽  
Unsteady Force

A numerical and experimental study of partial admission in a low reaction two-stage axial air test turbine is performed in this paper. In order to model one part load configuration, corresponding to zero flow in one of the admission arcs, the inlet was blocked at one segmental arc, at the leading edge of the first stage guide vanes. Due to the unsymmetrical geometry, the full annulus of the turbine was modeled numerically. The computational domain contained the shroud and disk cavities. The full admission turbine configuration was also modeled for reference comparisons. Computed unsteady forces of the first stage rotor blades showed cyclic change both in magnitude and direction while moving around the circumference. Unsteady forces of first stage rotor blades were plotted in the frequency domain using Fourier analysis. The largest amplitudes caused by partial admission were at first and second multiples of rotational frequency due to the existence of single blockage and change in the force direction. Unsteady forces of rotating blades in a partial admission turbine could cause unexpected failures in operation; therefore, knowledge about the frequency content of the unsteady force vector and the related amplitudes is vital to the design process of partial admission turbine blades. The pressure plots showed that the nonuniformity in the static pressure field decreases considerably downstream of the second stage’s stator row, while the nonuniformity in the dynamic pressure field is still large. The numerical results between the first stage’s stator and rotor rows showed that the leakage flow leaves the blade path down into the disk cavity in the admitted sector and re-enters downstream of the blocked channel. This process compensates for the sudden pressure drop downstream of the blockage but reduces the momentum of the main flow.

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