Finite Cavity Cascades With Low-Drag Pressure Distributions

1973 ◽  
Vol 95 (1) ◽  
pp. 8-16
Author(s):  
B. Yim
Keyword(s):  
Pressure Distribution ◽  
Finite Length ◽  
Nonlinear Approximation ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Two Dimensional ◽  
Method Of Calculation ◽  
Pressure Distributions

A method of calculation is presented for the flow characteristics of a two-dimensional supercavitating cascade with finite-length cavities and with an arbitrary pressure distribution. The principle of hydrofoil-airfoil correspondence of the infinite-cavity cascade is utilized. Simplified formulas for the drag and the cavity and foil shapes are derived, and several sample calculations are made. A nonlinear approximation for a thick leading-edge shape is also considered.

Two-dimensional planing at high Froude number

1958 ◽  
Vol 4 (5) ◽  
pp. 466-478 ◽  
Author(s):  
E. Cumberbatch
Keyword(s):  
Integral Equation ◽  
Pressure Distribution ◽  
Flat Plate ◽  
Froude Number ◽  
Water Surface ◽  
Flow Characteristics ◽  
Iteration Process ◽  
Leading Edge ◽  
Two Dimensional ◽  
High Froude Number

This paper examines the flow characteristics of a body of small slope planing at high Froude number over a water surface. An equation is obtained relating the slope of the planing surface to an integral containing the pressure distribution on the planing surface. The equation is expanded for large Froude number and a solution is obtained by an iteration process. At each stage of the iteration process the integral equation of ordinary thin aerofoil theory is solved. The pressure distribution on the planing surface is derived as a series in inverse powers of the Froude number F, as far as the F−4 term. Computations are performed for the planing of a flat plate, a parabolic surface, and a suitable linear combination of these shapes which results in a flow without a splash at the leading edge.

scholarly journals Dynamic flight load measurements with MEMS pressure sensors

2021 ◽  
Author(s):  
Christian Raab ◽  
Kai Rohde-Brandenburger
Keyword(s):  
Pressure Distribution ◽  
Pressure Sensors ◽  
Flow Characteristics ◽  
Flight Test ◽  
Measurement Technology ◽  
Test Program ◽  
Aerodynamic Pressure ◽  
Pressure Distributions ◽  
Time Histories ◽  
Mems Pressure Sensors

AbstractThe determination of structural loads plays an important role in the certification process of new aircraft. Strain gauges are usually used to measure and monitor the structural loads encountered during the flight test program. However, a time-consuming wiring and calibration process is required to determine the forces and moments from the measured strains. Sensors based on MEMS provide an alternative way to determine loads from the measured aerodynamic pressure distribution around the structural component. Flight tests were performed with a research glider aircraft to investigate the flight loads determined with the strain based and the pressure based measurement technology. A wing glove equipped with 64 MEMS pressure sensors was developed for measuring the pressure distribution around a selected wing section. The wing shear force determined with both load determination methods were compared to each other. Several flight maneuvers with varying loads were performed during the flight test program. This paper concentrates on the evaluation of dynamic flight maneuvers including Stalls and Pull-Up Push-Over maneuvers. The effects of changes in the aerodynamic flow characteristics during the maneuver could be detected directly with the pressure sensors based on MEMS. Time histories of the measured pressure distributions and the wing shear forces are presented and discussed.

Effect of Compressibility on Gaseous Flows in a Micro-Tube

2003 ◽  
Author(s):  
Yutaka Asako ◽  
Kenji Nakayama
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Pressure Distribution ◽  
Flow Characteristics ◽  
Fused Silica ◽  
Two Dimensional ◽  
Arbitrary Lagrangian Eulerian ◽  
Gaseous Flow ◽  
Gaseous Flows ◽  
Energy Equations

The product of friction factor and Reynolds number (f·Re) of gaseous flow in the quasi-fully developed region of a micro-tube was obtained experimentally and numerically. The tube cutting method was adopted to obtain the pressure distribution along the tube. The fused silica tubes whose nominal diameters were 100 and 150 μm, were used. Two-dimensional compressible momentum and energy equations were solved to obtain the flow characteristics in micro-tubes. The numerical methodology is based on the Arbitrary-Lagrangian-Eulerian (ALE) method. The both results agree well and it was found that (f·Re) is a function of Mach number.

Generalisation of the Condition for Waviness in the Pressure Distribution on a Cambered Plate

1963 ◽  
Vol 67 (632) ◽  
pp. 529-530 ◽  
Author(s):  
E. Angus Boyd
Keyword(s):  
Pressure Distribution ◽  
Surface Pressure ◽  
Leading Edge ◽  
Metal Plate ◽  
Two Dimensional ◽  
Striking Result ◽  
Surface Pressure Distribution

Recently some data from tests done on a cambered plate have been published. The shape of metal plate aerofoil tested matched that taken up by a flexible two-dimensional sail. The most striking result in the rneasurements was the waviness present near the leading edge in the upper surface pressure distribution. To find the theoretical conditions under which such a waviness would occur a parabolic skeleton aerofoil was investigated, as this shape differed little from the actual aerofoil tested.

Application of a Two-Dimensional Supersonic Passage Analysis to the Design of Compressor Rotors

1974 ◽  
Author(s):  
R. G. Hantman ◽  
A. A. Mikolajczak ◽  
F. J. Camarata
Keyword(s):  
Leading Edge ◽  
Inviscid Flow ◽  
Two Dimensional ◽  
Compressor Rotor ◽  
Pressure Distributions ◽  
Displacement Thickness ◽  
Blade Section ◽  
Comparison Of The Results ◽  
Rotational Method ◽  
Good Agreement

A description of a two-dimensional supersonic cascade passage analysis and its application to the design of a high hub-to-tip ratio supersonic compressor rotor is presented. The analysis, applicable to the case in which the inviscid flow is everywhere supersonic, includes an entrance region calculation which accounts for blade leading edge bluntness effects, and a passage and wake region calculation. The inviscid part of the analysis is solved using a rotational method of characteristics. The effect of the blade boundary layer displacement thickness is taken into consideration. Comparison of the results of the analysis with supersonic cascade data is made, showing good agreement in overall performance prediction, in blade surface static pressure distributions, and in achievement of the desired shock wave patterns. A comparison of the results of the analysis is made also with the performance of a blade section of a high hub-to-tip ratio supersonic compressor and acceptable agreement obtained.

The Normal Approach, Contact, and Rebound of Lubricated Cylinders

1983 ◽  
Vol 105 (2) ◽  
pp. 271-279 ◽  
Author(s):  
A. Chandra ◽  
R. J. Rogers
Keyword(s):  
Experimental Data ◽  
Pressure Distribution ◽  
Constant Load ◽  
Contact Forces ◽  
Solid Model ◽  
Two Dimensional ◽  
Load Case ◽  
Inertia Effects ◽  
Pressure Distributions ◽  
Present Technique

An algorithm has been developed to simulate the normal approach, contact, and rebound of lubricated cylinders. The detailed interaction between the lubricated cylinders is predicted, thus providing the pressure distribution, contact forces, and other variables useful in predicting rates of wear. The present technique improves on the existing elastohydrodynamic (EHD) models in the following areas: (1) during contact a solid-solid model is used; (2) a two-dimensional analysis is used to obtain the pressure distributions in both the circumferential and axial directions; (3) inertia effects are approximated; and (4) any specified load can be treated. The simulated results for the constant load case are compared with the results of Wada and Tsukijihara and a formula developed by Cameron. For sinusoidal loads the results are compared with experimental data from a cylinder and sleeve apparatus.

ANALYSIS OF THE EFFECTS OF MASS-INJECTION AT THE LEADING EDGE ON CAVITY FLOW CHARACTERISTICS

2009 ◽  
Vol 23 (03) ◽  
pp. 413-416 ◽  
Author(s):  
JI FEI WU ◽  
ZHAO LIN FAN ◽  
XIN FU LUO
Keyword(s):  
High Speed ◽  
Static Pressure ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Cavity Flow ◽  
Fluctuating Pressure ◽  
Pressure Distributions ◽  
Mass Injection ◽  
Varying Mass ◽  
Hole Number

An experimental investigation was conducted in a high speed wind tunnel to explore the effects of mass-injection on cavity flow characteristics. Detailed static-pressure and fluctuating pressure measurements were obtained at the cavity floor to enable the effects of the mass-injection at the leading edge to be determined. Results indicate that varying mass-injection hole number and the flux rate of mass-injection has no significant effect on cavity flow characteristics. However, mass-injection can reduce the cavity static pressure gradient when the cavity flow type is transitional-cavity flow. The study also indicates that Mach number can influence the effect of mass-injection on cavity fluctuating pressure distributions, and at supersonic speeds, mass-injection can suppress the cavity tones effectively.

Pressure Distributions and Forces on Rectangular and D-shaped Cylinders

1972 ◽  
Vol 23 (1) ◽  
pp. 1-6 ◽  
Author(s):  
B R Bostock ◽  
W A Mair
Keyword(s):  
Boundary Layer ◽  
Circular Cylinder ◽  
Drag Coefficient ◽  
Pressure Distribution ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Pressure Distributions ◽  
Two Dimensional Flow ◽  
Rectangular Cylinders ◽  
Shaped Section

SummaryMeasurements in two-dimensional flow on rectangular cylinders confirm earlier work of Nakaguchi et al in showing a maximum drag coefficient when the height h of the section (normal to the stream) is about 1.5 times the width d. Reattachment on the sides of the cylinder occurs only for h/d < 0.35.For cylinders of D-shaped section (Fig 1) the pressure distribution on the curved surface and the drag are considerably affected by the state of the boundary layer at separation, as for a circular cylinder. The lift is positive when the separation is turbulent and negative when it is laminar. It is found that simple empirical expressions for base pressure or drag, based on known values for the constituent half-bodies, are in general not satisfactory.

Two-Dimensional Contact Pressure Distribution of a Radial Tire in Motion

1996 ◽  
Vol 24 (4) ◽  
pp. 294-320 ◽  
Author(s):  
H. Shiobara ◽  
T. Akasaka ◽  
S. Kagami
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Fundamental Property ◽  
Leading Edge ◽  
Static Case ◽  
Two Dimensional ◽  
Contact Pressure Distribution ◽  
Radial Tire ◽  
Spring System ◽  
Tread Rubber

Abstract The two-dimensional contact pressure distribution of a running radial tire under load is a fundamental property of the tire structure. The two-dimensional contact pressure distribution in the static case and the one-dimensional contact pressure distribution in the dynamic case were previously analyzed for a spring bedded ring model consisting of a composite belt ring and a spring system for the sidewall and the tread rubber. In this paper, a Voigt-type viscoelastic spring system is assumed for the sidewall and the tread rubber. We analyzed the dynamic deformation of the belt ring in a steady state, and obtained the two-dimensional dynamic contact pressure distribution at speeds up to approximately 60 km/h. The predicted contact pressure distribution for a model with appropriate values for the damping coefficient of each constituent rubber is shown to be in good agreement with experimental results. It is a characteristic feature that increasing velocity yields an increase in the pressure at the leading edge of the crown centerline in the contact area and at the trailing edge of the shoulder line.

Rotor-Stator Interactions in a Four-Stage Low-Speed Axial Compressor—Part I: Unsteady Profile Pressures and the Effect of Clocking

2004 ◽  
Vol 126 (4) ◽  
pp. 507-518 ◽  
Author(s):  
Ronald Mailach ◽  
Konrad Vogeler
Keyword(s):  
Pressure Distribution ◽  
Axial Compressor ◽  
Leading Edge ◽  
Suction Side ◽  
Experimental Investigations ◽  
Low Speed ◽  
Unsteady Aerodynamic ◽  
Pressure Distributions ◽  
Blade Row ◽  
Pressure Changes

This two-part paper presents detailed experimental investigations of unsteady aerodynamic blade row interactions in the four-stage Low-Speed Research Compressor of Dresden. In part I of the paper the unsteady profile pressure distributions for the nominal setup of the compressor are discussed. Furthermore, the effect of blade row clocking on the unsteady profile pressures is investigated. Part II deals with the unsteady aerodynamic blade forces, which are calculated from the measured profile pressure distributions. The unsteady pressure distributions were analyzed in the first, a middle and the last compressor stage both on the rotor and stator blades. The measurements were carried out on pressure side and suction side at midspan. Several operating points were investigated. A complex behavior of the unsteady profile pressures can be observed, resulting from the superimposed influences of the wakes and the potential effects of several up- and downstream blade rows of the four-stage compressor. The profile pressure changes nearly simultaneously along the blade chord if a disturbance arrives at the leading edge or the trailing edge of the blade. Thus the unsteady profile pressure distribution is nearly independent of the convective wake propagation within the blade passage. A phase shift of the reaction of the blade to the disturbance on the pressure and suction side is observed. In addition, clocking investigations were carried out to distinguish between the different periodic influences from the surrounding blade rows. For this reason the unsteady profile pressure distribution on rotor 3 was measured, while stators 1–4 were separately traversed stepwise in the circumferential direction. Thus the wake and potential effects of the up- and downstream blade rows on the unsteady profile pressure could clearly be distinguished and quantified.

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