Wind Tunnel Balances (Experimental Fluid Mechanics)

✍ Scribed by Klaus Hufnagel

• Publisher: Springer
• Year: 2022
• Tongue: English
• Leaves: 294
• Category: Library

✦ Synopsis

This Handbook helps to design and build any kind of force measurement equipment for the use in a wind tunnel. It is of interest to those who want to build multi-component force measurement sensors for other applications as well. The book describes the basic relations for the design and presents handbook formulas that can be used to perform a primary determination of main dimensions of a specified multi-component force sensor. This Handbook describes material and manufacturing particularities, instrumentation techniques and methods for the compensation of environmental influences. It also discusses calibration problems of multi-component force sensors and methods for the evaluation of the data.

✦ Table of Contents

Preface
Contents
List of Figures
List of Tables
1 Historical Review
1.1 Introduction
1.2 From Fundamental Physics to the First Force Transducers
1.3 Force Measurement in Wind Tunnels
References
2 Basics
2.1 Basics of Wind Tunnel Balance System
2.2 Basic Terms of Balance Metrology
2.3 Definition of Axis Systems
2.4 Signal Conventions
2.5 Relevant Wind Tunnel Standards
References
3 Balance Types
3.1 External Balances
3.1.1 Weigh Beam Balances
3.1.2 Pyramidal Balance
3.1.3 Platform Balance
3.1.4 Coaxial Balances
3.1.5 Yoke Balance
3.1.6 Spiral Spring Type Balance
3.1.7 Half Model and Side Wall Balances
3.1.8 Three-Flange Balance
3.2 Internal Balances
3.2.1 Sting Balances
3.2.2 Box Balances
3.2.3 Floating Frame Balances
3.2.4 Rotating Balances
3.2.5 Hinge Moment Balances
3.2.6 Rudder Balances
3.2.7 Missile Balances
3.3 Magnetic Suspension Balances
3.4 Electromagnetic Balances
References
4 Model Mounting
4.1 Mounting of Models to External Balances
4.2 Mounting Models to Internal Balances
4.3 Correction of Mounting and Balance Elasticity
4.3.1 Correction by Sting Deformation Measurement
4.3.2 Correction by Model Position Measurement
4.3.3 Correction of Vibration by Active Sting Damping
4.4 Internal Balance Joints
4.4.1 Cone
4.4.2 Cylinder
4.4.3 Bloc
4.4.4 Flange
4.4.5 Summary Balance Joints
4.4.6 Adapters for the Use of Internal Balances as Box Balances and Vice Versa
References
5 Specification
5.1 Definition of Load
5.2 Specification of Balance Load Ranges
5.3 Dynamic Loads
5.4 Maximum Combined Load; Maximum Single Load
5.5 Safety Factors
5.6 Deflections
5.7 Constraints Due to Model Design (Space and Position)
5.8 Specific Load Parameter
5.9 Principle Design Equations (Feasibility)
5.10 Specification of Resolution, Repeatability and Sensitivities
5.10.1 Resolution
5.10.2 Repeatability
5.10.3 Sensitivity
5.11 Specification of Uncertainty
5.12 Specification of Thermal Characteristics
5.12.1 Operating Temperature Range
5.12.2 Zero Drift
5.12.3 Sensitivity Drift
5.12.4 Temperature Gradients
5.13 Balance Interfaces
5.14 Miscellaneous Specifications
5.14.1 Reference Planes and Reference Point
5.14.2 Moisture Protection
References
6 Design of Balances
6.1 Internal Balances
6.1.1 Moment and Force Separation Basic Design Equation
6.1.2 Specific Load Parameter
6.1.3 Routine Design Methods for Internal Balances
6.1.4 Design of Solid Bending Section of Internal Balances
6.1.5 Design of Cage Bending Section
6.1.6 Design of Axial Force Section
6.2 External Balances
6.2.1 Load Cells and Load Cell Arrangement
6.2.2 Weighbridge
6.2.3 Connecting Rods and Flexures
6.2.4 Temperature Problems of External Balances
6.3 Semi-span Balances
6.3.1 Thermal Problems of Semi-span Balances
6.4 Bridging
6.4.1 Model Data Bridging
6.4.2 Air Supply Bridging
6.5 Life Time and Fatigue Calculations
6.5.1 Determination of the Wöhler-Curve (S-N-Curve)
6.5.2 Stress Collective
6.5.3 Linear Damage Accumulation (Miner Rule)
6.5.4 Summary
References
7 Balance Material and Fabrication Methods
7.1 Balance Material
7.2 Material Characteristics
7.2.1 Tensile Strength and Yield Strength
7.2.2 Dynamic Stability and Fracture Toughness
7.2.3 Young's Module
7.2.4 Thermal Expansion Coefficient
7.2.5 Hysteresis
7.2.6 Creep
7.2.7 Heat Treatment
7.3 Maraging Steels
7.3.1 Heat Treatment of Maraging Steels
7.4 Stainless Steels
7.4.1 Heat Treatment of Stainless Steels
7.5 Copper Beryllium
7.5.1 Heat Treatment of Copper-Beryllium
7.6 Titanium Alloys
7.6.1 Heat Treatment of TiAl6V4
7.7 Aluminum Alloys
7.7.1 Heat Treatment of Aluminum Alloys
7.8 Balance Body Fabrication Methods
7.9 One Piece Fabrication
7.10 Multi-component Balances
7.11 Surface Protection
References
8 Strain Measurement
8.1 Strain Gauge
8.1.1 Wire Strain Gauge Fundamentals
8.1.2 Semiconductor Strain Gauge Fundamentals
8.1.3 Fiber Optic Strain Gauge Fundamentals
8.2 Strain Gauge Selection
8.3 Strain Gauge Application
8.3.1 Bonding
8.4 Wheatstone Bridge Wiring
8.4.1 Notation of Gauging and Wiring
8.4.2 Relation Between Signal and Resistance
8.4.3 Electrical Influence of Bridge Wires
8.4.4 Mechanical Influence of Bridge Wiring
8.5 Compensation of Bridge Zero Output
8.6 Compensation of Thermal Effects
8.6.1 Compensation of Zero Drift for Metal Foil Strain Gauges
8.6.2 Compensation of Sensitivity Shift of Metal Foil Strain Gauges
8.6.3 Computational Correction Methods of Temperature Effects
8.7 Direct Read Balance Wiring
8.8 Moment Balance Wiring
8.9 Insulation and Moisture Proofing
8.10 Connectors
8.11 Signal Conditioning Units
References
9 Calibration
9.1 Calibration Fundamentals
9.1.1 Calibration Theory and Problems
9.1.2 Mathematical Models
9.1.3 Description of Interactions
9.1.4 Tare Load Handling
9.1.5 Asymmetric Sensitivity
9.1.6 Verification and Accuracy
9.1.7 Traceability
9.1.8 Realignment
9.1.9 Signal Conditioning
9.2 Calibration Equipment
9.2.1 Calibration Sleeve
9.2.2 Weights
9.2.3 Position Measurement Equipment
9.2.4 Water Levels
9.2.5 Inclinometers; Accelerometers
9.2.6 Theodolite
9.2.7 Laser Based Position Measurement
9.2.8 Reference Load Cells
9.2.9 Cantilevers
9.2.10 Knife-Edge Bearings
9.2.11 Ball-Socket Bearings
9.2.12 Ball Bearings
9.2.13 Flexures
9.3 Calibration Principles
9.4 Direct Manual Calibration
9.4.1 Calibration Program
9.4.2 Evaluation Process
9.5 Calibration Machines
9.5.1 Indirect Automatic Calibration
9.5.2 Direct Automatic Calibration
References
10 Utilization of Balances in the Wind Tunnel
10.1 Rigging and Test Preparation
10.2 Damping Systems
References