Bezplatný inženýrský nástroj #037
Kalkulačka frekvence průchodu lopatek
Calculate the kinematic passage frequency for a known integer blade or vane count and measured shaft speed. Frequency alone does not predict amplitude or identify a fault.
Výsledky
Harmonické BPF
| Harmonická | Frekvence (Hz) | Násobek (× hřídel) | Perioda (ms) |
|---|
Passage frequency
Z is the integer number of recurring rotor elements, n is shaft speed in r/min, and fs is shaft rotational frequency. For a fixed observation point, Z equally recurring elements produce Z passages per revolution. ANSI/AMCA 301-22 gives this same fan blade-pass equation in its sound-rating method (Eq. 5.7).
Harmonické a postranní pásma
The table lists mathematical integer harmonics h·fBPF. Real spectra may contain BPF, harmonics and modulation components, but their presence and amplitude depend on rotor/stator geometry, flow, loading, sensor location, structure and acoustic response. A calculated line is a frequency marker, not a predicted spectral amplitude.
Diagnostic boundary
Do not diagnose from one line. A BPF peak, its harmonics or shaft-spaced sidebands do not uniquely prove clearance error, blade damage, fouling, resonance, recirculation or cavitation. Compare like-for-like operating points with baseline/trend data and use corroborating phase, waveform, pressure, acoustic, process and inspection evidence. Cavitation assessment also requires hydraulic operating and NPSH evidence.
Worked calculation
fs = 2950/60 = 49.1667 Hz
fBPF = 6 × 49.1667 = 295 Hz
Perioda = 1/295 = 3.3898 ms; 2×BPF = 590 Hz; 3×BPF = 885 Hz.
Sources and standard scope
- ANSI/AMCA Standard 301-22, Eq. 5.7 — fan blade-pass frequency.
- NASA technical report 20030064154 — BPF/harmonics in rotor–stator forced response and modulation context.
- Grundfos cavitation reference — cavitation and NPSH context.
Rozsah: steady shaft speed and one integer count of equally recurring elements. Variable speed smears or sweeps the frequency; nonuniform pitch can create additional components. This calculator is not an ISO severity or acceptance assessment.
Profesionální přístroje pro analýzu vibrací pro diagnostiku ventilátorů a čerpadel, vyvažování v provozu a monitorování stavu. Používají se ve více než 50 zemích.
