Flame Height (Heskestad)
Estimate the mean height of a diffusion flame by the Heskestad correlation, L = 0.235·Q̇^(2/5) − 1.02·D, from the heat release rate Q̇ (kW) and the fire base diameter D (m). The result, in metres, is the visible flame height above the base — essential to assess the risk of fire spread by radiation, the thermal reach over structures and the activation of detectors and sprinklers. Height grows with the fire power to the 2/5 power and decreases with the base diameter. It is one of the classic fire dynamics correlations. Enter the heat release rate and the base diameter.
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Altura de chama (correlação de Heskestad)
A altura da chama de um incêndio não é um detalhe estético — ela determina o quão longe o fogo alcança por radiação e contato direto, se vai atingir o teto (espalhando-se horizontalmente), e quando aciona detectores e chuveiros. A correlação mais usada para estimá-la é a de Heskestad: L = 0,235·Q̇^(2/5) − 1,02·D, onde Q̇ é a taxa de liberação de calor (potência do fogo, em kW) e D é o diâmetro (ou dimensão característica) da base do fogo (m). O resultado é a altura média visível da chama acima da base, em metros. A física por trás é elegante: a altura cresce com a potência elevada a 2/5 (um fogo 32× mais potente tem chama só 4× mais alta), e o termo −1,02·D reflete que, para uma mesma potência, um fogo espalhado numa base larga produz chamas mais baixas que um fogo concentrado (a combustão se distribui). Chamas reais tremulam, então 'altura média' significa a altura em que a chama está presente cerca de 50% do tempo. Essa correlação é uma das pedras angulares da dinâmica do fogo e alimenta os cálculos de propagação, de fluxo de calor sobre estruturas e paredes vizinhas, e de ativação de sistemas de detecção e supressão. Informe a taxa de liberação de calor e o diâmetro da base.
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Heat Release Rate (HRR)
Calculate the heat release rate of a fire (HRR), Q̇ = ṁ × ΔH_c, multiplying the fuel burning rate (kg/s) by the effective heat of combustion (MJ/kg). The result, in MW, is the fire's power — the single most important quantity in fire science, governing gas temperatures, flame height, smoke production and spread rate. It is the fundamental input to fire safety engineering models and to the design of smoke control and detection systems. Enter the burning rate and the heat of combustion.
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L10 Life in Hours (Bearing)
Calculate a bearing's nominal L10 life in HOURS of operation, L10h = (10⁶ ÷ (60·n))·(C/P)^p, from the dynamic load rating C (N), the equivalent dynamic load P (N), the rotation n (rpm) and the exponent p (3 for ball bearings, 10/3 for roller bearings). L10 life is the core of bearing selection: the number of revolutions (or hours) that 90% of a batch of identical bearings reaches or exceeds before FATIGUE failure (spalling of races and rolling elements) — i.e., only 10% fail earlier (hence 'L10', the life with 90% reliability). The basic formula L10 = (C/P)^p gives life in MILLIONS of revolutions; dividing by the rotation (rpm × 60 min/h) converts to hours, the practical unit for machines. The result shows the huge load sensitivity: since the exponent is 3 (balls), DOUBLING the load cuts life to 1/8! So a slightly overloaded bearing lasts far less. The capacity C is tabulated in each bearing's catalog. This calculation decides whether a bearing meets the application's required life (typically 20,000-100,000 h for industrial machines) or whether a larger one is needed. Enter the dynamic capacity, the equivalent load, the rotation and the exponent.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.