**In depth analysis of the working principle of Roots blower**
Roots blower is a type of volumetric gas conveying equipment that achieves forced gas delivery through the rotation of two interlocked impellers. Its core features are * * no internal compression, constant flow rate, and simple structure * *. The following is a detailed analysis of its working principle:
---
**1、 Core work process**
1. * * Inhalation stage**
-When the impeller rotates, the volume of the intake chamber increases → negative pressure is formed → gas is sucked in
-* * Key Parameters * *:
-Inlet pressure: normal pressure (or slight negative pressure)
-Impeller clearance: 0.1~0.4mm (ensuring airtightness)
2. * * Closed conveying stage**
-The gas is enclosed within the cavity formed by the impeller and the casing
-* * No internal compression * *: Gas is only pushed inside the chamber and not actively compressed
-Synchronous gear ensures non-contact rotation of impeller (clearance fit)
3. * * Exhaust Stage**
-The volume of the exhaust chamber decreases → the gas is forcibly discharged
-* * Exhaust pressure * *: depends on system resistance (usually 9.8~98kPa)
```mermaid
graph LR
A [Inhalation] -->B [Closed Conveyor] -->C [Exhaust]
```
---
**2、 Dynamic characteristics**
1. * * Traffic calculation**
\[
Q = 4 \times \lambda \times n \times V_{th}
\]
-(Q): Actual flow rate (m3/min)
-\ (\ lambda \): Volumetric efficiency (0.75~0.85)
-(n): Speed (rpm)
-\ (V_ {th} \): Theoretical displacement (m3/rev, related to the geometric dimensions of the impeller)
2. * * Pressure characteristics**
-Theoretical pressure depends only on system resistance
-Actual limiting factors:
-Gear strength (usually limited to within 98kPa)
-Bearing bearing capacity
---
**3、 The essential difference from centrifugal fans**
|* * Features * * | * Roots blower * * | * * Centrifugal blower * *|
|----------------|--------------------------|--------------------------|
|* * Working principle * * | Volumetric (forced delivery) | Kinetic (centrifugal force)|
|* * Flow Curve * * | Steep Drop (Constant Flow) | Smooth (Pressure Sensitive)|
|Efficiency range * * | 60~75 | 80~90|
|* * Noise characteristics * * | High frequency pulsation (requires muffler) | Wide frequency noise|
---
**4、 Collaborative effect of key components**
1. * * Impeller**
-Profile design: involute (low noise) or cycloid (rate)
-Material: Cast iron (HT250), stainless steel (316L)
2. * * Synchronous gear**
-Hard tooth surface quenching (C58~62)
-Accuracy level: ISO level 5 (ensuring impeller synchronization)
3. * * Sealing system**
-Shaft seal: mechanical seal (pressure resistance 0.6MPa)
-Wall panel sealing: Fluororubber O-ring
---
**5、 Typical application scenarios**
1. * * Sewage treatment aeration**
-Requirement: Constant flow oxygen supply (pressure 49~78.4kPa)
-Advantage: Not affected by changes in water level
2. * * Pneumatic conveying**
-Powder conveying (solid to gas ratio of 20~30)
-Anti static design is required (surface resistance<10 Ω)
3. * * Vacuum system**
-Reverse use can achieve a vacuum degree of -50kPa
-Case: Medical Center Gas Supply System
---
**6、 Technological Evolution Trends**
1. * * Translation**
-Three element flow impeller design (efficiency improvement of 8-12)
2. * * Intelligentization**
-Integrated vibration/temperature wireless monitoring
3. * * Low noise**
-Twisted blade design (noise<75dB (A))
---
**Note: The incompressible characteristics of Roots blowers make them irreplaceable in scenarios where stable flow is required, but their efficiency is lower than that of centrifugal blowers. When selecting, it is important to consider the system's resistance characteristics and flow requirements.
