Mekanika Fluida FM01 (Lecture3: 7/8). Static-Pitot Tube

Introduction

This tutorial provides a comprehensive guide on the concepts presented in the lecture about static-Pitot tubes in fluid mechanics. Understanding these principles is essential for students and professionals in engineering fields such as mechanical, chemical, aerospace, and environmental engineering. This guide will cover the fundamentals of fluid behavior, pressure measurement, and practical applications of static-Pitot tubes.

Step 1: Understand Fluid Concepts

Before diving into the static-Pitot tube, it's crucial to grasp the basic principles of fluid mechanics.

• Viscosity: This property describes how a fluid resists flow. Higher viscosity means the fluid flows less easily.
• Newton's Law of Viscosity: Relates shear stress to shear strain rate in fluids, which is foundational for understanding fluid behavior.

Practical Tip

Familiarize yourself with charts or tables that provide viscosity values for common fluids, as this will help in practical applications.

Step 2: Explore Hydrostatics

Hydrostatics is the study of fluids at rest, and it includes key concepts that are important for measuring pressure.

• Hydrostatic Pressure: The pressure exerted by a fluid at rest due to the weight of the fluid above it.
• Pascal’s Principle: States that changes in pressure applied to an enclosed fluid are transmitted undiminished throughout the fluid.

Common Pitfall

Avoid neglecting the effects of fluid density and height in pressure calculations, as these factors significantly impact measurements.

Step 3: Learn About Manometry

Manometry involves measuring fluid pressure using a manometer, which is essential for understanding how static-Pitot tubes function.

• Types of Manometers: Open and closed manometers can be used depending on the application.
• Measurement Technique: The height difference in the manometer fluid indicates the pressure difference.

Practical Application

Use manometers in laboratory settings to measure the pressure of various fluids, which enhances your understanding of hydrostatic principles.

Step 4: Introduction to Bernoulli's Equation

Bernoulli's Equation relates pressure, velocity, and elevation in flowing fluids.

• Equation: [ P + \frac{1}{2} \rho v^2 + \rho g h = \text{constant} ] Where:
  • (P) is the pressure,
  • (\rho) is fluid density,
  • (v) is flow velocity,
  • (g) is gravitational acceleration,
  • (h) is height above a reference point.

Real-World Application

Apply Bernoulli's equation to analyze fluid flow in pipes, which is particularly useful in engineering design.

Step 5: Understanding Static-Pitot Tubes

Static-Pitot tubes are instruments used to measure fluid velocity by comparing static and dynamic pressures.

• Components: The Pitot tube consists of a tube with two openings; one measures static pressure and the other measures total pressure.
• Operation: The difference in pressure readings allows for the calculation of fluid velocity.

Calculation Example

To find the fluid velocity ((v)):

1. Measure (P_t) (total pressure) and (P_s) (static pressure).
2. Calculate the dynamic pressure: [ P_d = P_t - P_s ]
3. Use the equation: [ v = \sqrt{\frac{2(P_d)}{\rho}} ]

Conclusion

Understanding the principles of fluid mechanics, hydrostatics, and the operation of static-Pitot tubes is crucial for students in engineering disciplines. By mastering these concepts, you will be equipped to apply them in practical scenarios, such as designing systems involving fluid flow. For further study, explore advanced topics related to viscous flow and the applications of Bernoulli's equation in real-world engineering problems.