BTech Tuition

BTech Civil Engineering

Trending Questions and Lessons

Follow 57,950 Followers

Ask a Question

Feed

All

All

Lessons

Discussion

Asked on 05/07/2017 Tuition/BTech Tuition/BTech Civil Engineering

M.tech Structures or M.arch in Planning? What has more demand nowadays?

Answer

Lesson Posted on 27/05/2017 Tuition/BTech Tuition Tuition/BTech Tuition/BTech Civil Engineering Exam Coaching/Engineering Entrance Coaching/GATE Coaching +2 Exam Coaching/Engineering Entrance Coaching/GATE Coaching/Civil Tuition/BTech Tuition/Basic Mechanical Engineering less

Drag And Its Classifications

BATTA SHIVAJI

I was completed B.Tech, recently qualified in GATE exam and completed IES coaching in Made Easy center....

Introduction Drag is the enemy of flight and its cost. One group of those forces is aerodynamic forces that split into two forces: Lift force or lift, and Drag force or drag. A pre-requisite to aircraft performance analysis is the ability to calculate the aircraft drag at various flight conditions.... read more

Introduction

Drag is the enemy of flight and its cost. One group of those forces is aerodynamic forces that split into two forces: Lift force or lift, and Drag force or drag. A pre-requisite to aircraft performance analysis is the ability to calculate the aircraft drag at various flight conditions. One of the jobs of a performance engineer is to determine drag force produced by an aircraft at different altitudes, speeds and configurations. This is not an easy task, since; this force is a function of several parameters including aircraft configuration and components. As it was discussed in chapter 2, the drag is a function of aircraft speed, wing area, air density, and its configuration. Each aircraft is designed with a unique configuration, thus, aircraft performance analysis must take into account this configuration. The configuration effect of aircraft drag is represented through the drag coefficient (CD), plus a reference area that relates to the aircraft.

An aircraft is a complicated three-dimensional vehicle, but for simplicity in calculation, we assume that the drag is a function a two-dimensional area and we call it the reference area. This area could be any area including tail area, wing area and fuselage cross sectional area (i.e., fuselage cross section), fuselage surface area, and even aircraft top-view area. No matter what area is selected, the drag force must be the same. This unique drag comes from the fact that the drag coefficient is a function of the reference area. Therefore, if we select a small reference area, the drag coefficient shall be large, but if we choose a large reference area, the drag coefficient shall be small. In an air vehicle with a small wing area (e.g., high-speed missile), the fuselage cross-sectional area (normal to the flow) is often considered as the reference area. However, in an aircraft with a large wing, the top-view of wing; plan form area (in fact gross wing area) is often assumed to be the reference area.

 

The drag coefficient (CD) is a non-dimensional parameter, but it takes into account every aerodynamic configuration aspect of the aircraft including large components as wing, tail, fuselage engine, and landing gear; and small elements such as rivets and antenna. This coefficient has two main parts (as will be explained in the next section). The first part is referred to as lift-related drag coefficient or induced drag coefficient (CDi) and the second part is called zero-lift drag coefficient (CDo). The calculation of the first one is not very hard, but it takes a long time and energy to determine the second part. In large transport aircraft, this task is done by a group of engineers up to twenty engineers for a time period of up to six months. For this reason, a large portion of this chapter is devoted to the calculation of CDo. This calculation is not only time consuming, but also is very sensitive, since it influences every aspect of aircraft performance.

One of the occasions in which the drag is considered a beneficial factor and is effectively used is in parachute. A parachute is a device employed to considerably slow the motion of an object/vehicle through an atmosphere (e.g., Earth or Mars) by increasing drag. Parachutes are used with a variety of loads, including people, food, equipment, and space capsules. Drogue chutes are used to sometimes provide horizontal deceleration of a vehicle (e.g., space shuttle after a touchdown). The parachute is utilized by paratroopers to extremely reduce the terminal speed for a safe landing.

One of the primary functions of aerodynamicists and aircraft designers is to reduce this coefficient. Aircraft designers are very sensitive about this coefficient, because any change in the external configuration of aircraft will change this coefficient and finally aircraft direct operating cost. As a performance engineer, you must be able to estimate the CDo of any aircraft just by looking at its three-view with an accuracy of about 30%. As you spend more time for calculation, this estimation will be more accurate, but will never be exact, unless you use an aircraft model in a wind tunnel or flight test measurements with real aircraft model. The method presented in this chapter is about 90% accurate for subsonic aircraft and 85% for supersonic aircraft.

Drag Classification

Drag force is the summation of all forces that resist against aircraft motion. The calculation of the drag of a complete aircraft is a difficult and challenging task, even for the simplest configurations. We will consider the separate sources of drag that contribute to the total drag of an aircraft. The variation of drag force as a function of airspeed looks like a graph of parabola. This indicates that the drag initially reduces with airspeed, and then increases as the airspeed increases. It demonstrates that there are some parameters that will decrease drag as the velocity increases; and there are some other parameters that will increase drag as the velocity increases. This observation shows us a nice direction for drag classification. Although the drag and the drag coefficient can be expressed in a number of ways, for reasons of simplicity and clarity, the parabolic drag polar will be used in all main analyses. Different references and textbooks use different terminology, so it may confuse students and engineers. In this section, a list of definitions of various types of drag is presented, and then a classification of all of these drag forces is described.

Induced Drag:

The drag that results from the generation of a trailing vortex system downstream of a lifting surface with a finite aspect ratio. In another word, this type of drag is induced by the lift force.

Parasite Drag:

The total drag of an airplane minus the induced drag. Thus, it is the drag not directly associated with the production of lift. The parasite drag is composed of drag of various aerodynamic components; the definitions of which follow.

Skin Friction Drag:

The drag on a body resulting from viscous shearing stresses (i.e., friction) over its contact surface (i.e., skin). The drag of a very streamlined shape such as a thin, flat plate is frequently expressed in terms of a skin friction drag. This drag is a function of Reynolds number. There are mainly two cases where the flow in the boundary layer is entirely laminar or entirely turbulent over the plate. The Reynolds number is based on the total length of the object in the direction of the velocity. In a usual application, the boundary layer is normally laminar near the leading edge of the object undergoing transition to a turbulent layer at some distance back along the surface.

A laminar boundary layer begins to develop at the leading edge and its thickness grows in downstream. At some distance from the leading edge the laminar boundary becomes unstable and is unable to suppress disturbances imposed on it by surface roughness or fluctuations in the free stream. In a distance the boundary layer usually undergoes a transition to a turbulent boundary layer. The layer suddenly increases in thickness and is characterized by a mean velocity profile on which a random fluctuating velocity component is superimposed. The distance, from the leading edge of the object to the transition point can be calculated from the transition Reynolds number. Skin friction factor is independent of surface roughness in laminar flow, but is a strong function of surface roughness in turbulent flow due to boundary layer.

Form Drag (sometimes called Pressure Drag):

The drag on a body resulting from the integrated effect of the static pressure acting normal to its surface resolved in the drag direction. Unlike the skin friction drag that results from viscous shearing forces tangential to a body’s surface, form drag results from the distribution of pressure normal to the body’s surface. In an extreme case of a flat plate normal to the flow, the drag is totally the result of an imbalance in the pressure distribution. As with skin friction drag, form drag is generally dependent on Reynolds number. Form drag is based on the projected frontal area. As a body begins to move through the air, the vorticity in the boundary layer is shed from the upper and lower surfaces to form two vortices of opposite rotation. A number of symmetrical shapes having drag values at low speed are illustrated in Table 3.1. The drag coefficient values in this table are based on the frontal area. In this table, the flow is coming from left to the right.

Interference Drag:

The increment in drag resulting from bringing two bodies in proximity to each other. For example, the total drag of a wing-fuselage combination will usually be greater than the sum of the wing drag and fuselage drag independent of each other.

Trim Drag:

The increment in drag resulting from the (tail) aerodynamic forces required to trim the aircraft about its center of gravity. Trim drag usually is a form of induced and form drag on the horizontal tail.

Profile Drag:

Usually taken to mean the total of the skin friction drag and form drag for a two-dimensional airfoil section.

Cooling Drag:

The drag resulting from the momentum lost by the air that passes through the power plant installation for the purpose of cooling the engine.

Wave Drag:

This drag; limited to supersonic flow; is a form of induced drag resulting from non-canceling static pressure components to either side of a shock wave acting on the surface of the body from which the wave is emanating.

 

read less
Comments
Dislike Bookmark

Lesson Posted on 19/05/2017 Tuition/BTech Tuition Tuition/Engineering Diploma Tuition Tuition/Engineering Diploma Tuition/Civil Construction And Survey +3 Tuition/BTech Tuition/BTech Civil Engineering Exam Coaching/Engineering Entrance Coaching/GATE Coaching Exam Coaching/Engineering Entrance Coaching/GATE Coaching/Civil less

Types of Survey

BATTA SHIVAJI

I was completed B.Tech, recently qualified in GATE exam and completed IES coaching in Made Easy center....

Surveying Surveying is defined as a measurement of any two relative positions on the Earth or below the Earth or above the Earth. Types of Surveying On the basis of whether the the curvature of the earth is taken into account or not, surveying can be devided into two main catrgories; 1) Plane Surveying Plane... read more

Surveying

Surveying is defined as a measurement of any two relative positions on the Earth or below the Earth or above the Earth.

Types of Surveying

On the basis of whether the the curvature of the earth is taken into account or not, surveying can be devided into two main catrgories;

1) Plane Surveying

  • Plane surveying is the type of surveying where the mean surface of the earth is considered as a plane
  • For small areas less than 250 square kilometer plane surveying can safely be used

2) Geodetic Surveying

Geodetic Surveying is that branch of surveying which takes into account the true shape of the Earth (spheriod)

Surveying may be classified on the basis of nature of the survey field, object of survey, instruments used and the methods employed.

Classification Based on Nature of Survey Field

This basis survey may be classified as land survey, marine or hydraulic survey and astronomical survey.

Land Survey: It involves measurement of various objects on land. This type of survey may be further classified as given below:

(a) Topographic Survey: It is meant for plotting natural features like rivers, lakes, forests and hills as well       as man made features like roads, railways, towns, villages and canals.

(b) Cadastral Survey: It is for marking the boundaries of municipalities, villages, talukas, districts, states        etc. The survey made to mark properties of individuals also come under this category.

(c) City Survey: The survey made in connection with the construction of streets, water supply and sewage      lines fall under this category.

Marine or Hydrographic Survey

Survey conducted to find depth of water at various points in bodies of water like sea, river and lakes fall under this category. Finding depth of water at specified points is known as sounding.

Astronomical Survey

Observations made to heavenly bodies like sun, stars etc., to locate absolute positions of points on the earth and for the purpose of calculating local time is known as astronomical survey

Classification Based on Object of Survey

On the basis of object of survey the classification can be as engineering survey, military survey, mines survey, geological survey and archeological survey. (a) Engineering Survey: The objective of this type of survey is to collect data for designing civil engineering projects like roads, railways, irrigation, water supply and sewage disposals. These surveys are further sub-divided into: Reconnaissance Survey for determining feasibility and estimation of the scheme. Preliminary Survey for collecting more information to estimate the cost of the project, and Location Survey to set the work on the ground.

(b) Military Survey: This survey is meant for working out plans of strategic importance.

(c) Mines Survey: This is used for exploring mineral wealth.

(d) Geological Survey: This survey is for finding different strata in the earth’s crust.

(e) Archeological Survey: This survey is for unearthing relics of antiquity.

Classification Based on Instruments Used

Based on the instruments used, surveying may be classified as:

(i) Chain survey (ii) Compass survey (iii) Plane table survey (iv) Theodolite survey (v) Tacheometric survey (vi) Modern survey using electronic distance meters and total station (vii) Photographic and Aerial survey

The survey is taught to civil engineering students mainly based on this classification.

Classification Based on Methods Employed

On this basis surveying is classified as triangulation and traversing.

(i) Triangulation: In this method control points are established through a network of triangles

(ii)Traversing : In this scheme of establishing control points consists of a series of connected points established through linear and angular measurements. If the last line meets the starting point it is called as closed traverse. If it does not meet, it is known as open traverse.

read less
Comments
Dislike Bookmark

Looking for BTech Tuition

Find best BTech Tuition in your locality on UrbanPro.

FIND NOW

Lesson Posted on 22/02/2017 Tuition/BTech Tuition/BTech Civil Engineering Tuition/Engineering Diploma Tuition Tuition/Engineering Diploma Tuition/Civil Engineering Diploma

Strain Energy Stored Due To Axial Loading

Raviteja

Let us assume a member with uniform cross section A and of lenth l, be subjected to external axial load W as shown in the figure. As the load is gradually applied the load is incresed from 0 to W, due to which the member is gradually extended by Δ. Work done due to load is given by the product... read more

Let us assume a member with uniform cross section A and of lenth l, be subjected to external axial load W as shown in the figure.

As the load is gradually applied the load is incresed from 0 to W, due to which the member is gradually extended by Δ.

Work done due to load is given by the product of avarage load and the displacement Δ.

   work done = 1/2 * W * Δ

Let the tenstion developed in the member be T, @ Equilibrium W = T

   Tensile stress (ƒ) = T/A

   Tensile strain(e) = ƒ/E = T/AE

   Δ = el = S/AE *l]

Strain Energy Stored = Work Done = 1/2*W*Δ = 1/2*T*Tl/AE = T2l/2AE

 

Strain Energy Stored per unit volume = (T2l/2AE)/V =T2/2A2E=ƒ2/2E)

                                        

read less
Comments
Dislike Bookmark

Lesson Posted on 02/01/2017 IT Courses/ETABS Cad Staad Pro classes Tuition/BTech Tuition +5 Tuition/BTech Tuition/BTech Civil Engineering Tuition/MTech Tuition Tuition/MTech Tuition/Civil Engineering Tuition/BTech Tuition/Civil Engineering Materials And Construction IT Courses/Autocad less

ETABS vs Other Analysis Software

Premjit Vasudevan

I am chartered Engineer with 17 years of experience in analysis and design of civil structures using...

ETABS is a powerful tool for Analysis and it wins hands down over many other analysis tools in tall building structural analysis and design. The main advantages are 1) Its modelling and result interpretation interface is one of the easiest 2) It can perform P -Delta and response spectrum analysis/dynamic... read more

ETABS is a powerful tool for Analysis and it wins hands down over many other analysis tools in tall building structural analysis and design.

The main advantages are

1) Its modelling and result interpretation interface is one of the easiest

2) It can perform P -Delta and response spectrum analysis/dynamic analysis.

3) Construction sequencing loading can be done.

4) Latest 2016 version of ETABS comes with many options available in SAFE

5) Compatible with REVIT 

 

read less
Comments
Dislike Bookmark

Answered on 23/11/2016 Tuition/BTech Tuition Tuition/BTech Tuition/BTech Civil Engineering

Rajesh Talluri

Geotechnical Engineer

Learn how to understand the concept by taking tutorials from Geo technical engineering background tutor.
Answers 20 Comments
Dislike Bookmark

Looking for BTech Tuition

Find best BTech Tuition in your locality on UrbanPro.

FIND NOW

Lesson Posted on 30/08/2016 Cad Staad Pro classes Tuition/MTech Tuition/Civil Engineering Tuition/BTech Tuition +5 Tuition/BTech Tuition/BTech Civil Engineering IT Courses/CAD IT Courses/ETABS Tuition/MTech Tuition Tuition/Engineering Diploma Tuition less

DUCTILE DETAILING AND ITS SIGNIFICANCE + HOW TO ACHIEVE DUCTILITY

Premjit Vasudevan

I am chartered Engineer with 17 years of experience in analysis and design of civil structures using...

Ductility of Buildings is a key virtue. Ductility is the ability to prolong yielding or in simple words, prolonging deformation and failure.Why should we prolong yielding of steel?As we know, we design to resist a certain earth quake acceleration/ground movement (based on zone where the building is located)... read more

Ductility of Buildings is a key virtue. Ductility is the ability to prolong yielding or in simple words, prolonging deformation and failure.Why should we prolong yielding of steel?As we know, we design to resist a certain earth quake acceleration/ground movement (based on zone where the building is located) and not for unlimited ground acceleration.The zoning of places is done by looking at the history of seismic activity in the region and by studying the soil strata. This does not mean that an earth quake of more severity will never occur. Earth quake is a natural occurrence and we can only have an approximate estimation and hence ductility is as much important. What if in a location like Bangalore where it is zoned as Zone 2,experiences a larger seismic acceleration similar to that expected in Zone 3.The building would have been designed only for a seismic acceleration expected in Zone 2.However due to larger acceleration, chances of irreparable damages are more.

By plugging in a certain ductility will help in reducing the irreparable damages.

Also in case of a larger ground movement, it helps in increasing the evacuation time there by saving lives.


How do we achieve ductility and will this cost more?A structural engineer builds up a model and simulate the acceleration  and compute the deformation and the related forces developed in all members and designs. There are some design considerations and detailing principles  for achieving ductility and it is mandatory to do so in Zone 3 and above for all buildings irrespective of size or height.Basically, the overall amount of shear steel ie the links/stirrups increases and the overall amount of longitudinal steel slightly reduces when we do ductility design+ductile detailing.ie, Between, Just a seismic design vs seismic design + ductile consideration will keep the total steel quantity almost same. In zone 2 , seismic resistant design is mandatory irrespective of size or height of the building. Ductility design/detailing is not mandatory. However as mentioned before, zone 2 may experience larger scale acceleration and to prevent damages, a little addition of ductility is desirable. This can be achieved by using Fe500 D steel instead of Fe500 at a nominal additional cost. Also the stirrups in joints and laps shall be closely spaced.Conclusion : Safety is a virtue as much important as function and a nominal increase or sometimes no increase in cost  can ensure this. All required is a careful attention and consideration.

DUCTILE DETAILING

read less
Comments
Dislike Bookmark

Answered on 09/07/2016 Tuition/BTech Tuition Tuition/BTech Tuition/BTech Civil Engineering Tuition/MTech Tuition +1 Tuition/MTech Tuition/Civil Engineering less

K.naresh

YOU HAVE IIT'S NIT'S AND JNTU'S and lot of private colleges
Answers 4 Comments
Dislike Bookmark

Asked on 03/06/2016 Tuition/BTech Tuition Tuition/BTech Tuition/BTech Civil Engineering

hello sir i am very confused which courses i will do after 12 pass [PCM] PLEASE SUGGEST ME

Answer

Looking for BTech Tuition

Find best BTech Tuition in your locality on UrbanPro.

FIND NOW

Asked on 15/03/2016 Tuition/BTech Tuition Tuition/BTech Tuition/BTech Civil Engineering

In force method of analysis how to use virtual work principle?

Answer

About UrbanPro

UrbanPro.com helps you to connect with the best BTech Tuition in India. Post Your Requirement today and get connected.

Overview

Lessons 11

Total Shares  

Related Topics

Top Contributors

Connect with Expert Tutors & Institutes for BTech Civil Engineering

x

Ask a Question

Please enter your Question

Please select a Tag

UrbanPro.com is India's largest network of most trusted tutors and institutes. Over 25 lakh students rely on UrbanPro.com, to fulfill their learning requirements across 1,000+ categories. Using UrbanPro.com, parents, and students can compare multiple Tutors and Institutes and choose the one that best suits their requirements. More than 6.5 lakh verified Tutors and Institutes are helping millions of students every day and growing their tutoring business on UrbanPro.com. Whether you are looking for a tutor to learn mathematics, a German language trainer to brush up your German language skills or an institute to upgrade your IT skills, we have got the best selection of Tutors and Training Institutes for you. Read more