Kingery-Bulmash Blast Wave Characteristics Calculator

Python implementation of the Simplified Kingery Airblast Formulas and Coefficients from:

Simplified Kingery Airblast Calculations

Swisdak, Jr, Michael M.
NAVAL SURFACE WARFARE CENTER INDIAN HEAD DIV MD
1994 Aug 01
Accession Number: ADA526744
Security Classification: UNCLASSIFIED

Applicable for TNT equivalent NEQ (Net Explosive Quantity) and hemispherical surface bursts.

Installation

Using pip to install from PyPI:

pip install kingery-bulmash

Usage

import kingery_bulmash as kb

Use prefix kb. to import all required objects. An example for a TNT eqivalent NEQ of 10,000 kg at 500 m:

import kingery_bulmash as kb

# for metric units: 10000kg at 500m
res = kb.Blast_Parameters(unit_system=kb.Units.METRIC, 
                          neq=10000, 
                          distance=500)

print(res)

Expand to see console output

Blast Parameters (Kingery-Bulmash)
NEQ: 10000 kg
Distance: 500 m
Time of Arrival: 1276.1650108864796 ms
Incident Pressure: 5.0549639655028455 kPa
Reflected Pressure: 10.244621193146642 kPa
Positive Phase Duration: 133.23344980362697 ms
Incident Impulse: 295.87689480141484 kPa-ms
Reflected Impulse: 1063.0270073779907 kPa-ms
Shock Front Velocity: 347.3295095310771 m/s

kb.Units

The kb.Units Enum is how we select the units for the calculation, it needs to be passed to kb.Blast_Parameters as either kb.Units.METRIC or kb.Units.IMPERIAL.

• kb.Units.METRIC

  for neq in kg and distance in m.

• kb.Units.IMPERIAL

  for neq in lb and distance in ft.

Important

The library does not convert between units. Rather, it uses the metric and imperial parameters from the paper directly, therefore there might be slight differences between the results.

kb.Blast_Parameters

class kb.Blast_Parameters(unit_system, neq, distance, safe=True)

The Blast_Parameters dataclass calculates all the Kingery-Bulmash parameters from the paper.

Attributes:

• unit_system : kb.Units.METRIC or kb.Units.IMPERIAL

  Defines the unit system of the imput and calculated results. See kb.Units section here.

• neq: float

  TNT equivalent net explosive quantity. kg or lb based on unit_system.

• distance: float

  Distance from the explosive. m or ft based on unit_system.

• safe: bool, optional

  When True (default), kb.Blast_Parameters will raise a ValueError if any attribute is out of range. When False any attribute out of range will be set to None without raising a ValueError, this allows to significantly expand the range of values for less sensitive attributes. Default is True.

Tip

Blast_Parameters can raise Exception and ValueError, it is recommended to use try and except to handle this this behaviour. Python Errors Tutorial.

__post_init__ attributes:

• time_of_arrival: float, None

  Time of arrival in ms.

• incident_pressure: float, None

  Incident pressure in kPa or psi based on unit_system.

• reflected_pressure: float, None

  Reflected pressure in kPa or psi based on unit_system.

• positive_phase_duration: float, None

  Positive phase duration in ms.

• incident_impulse: float, None

  Incident inpulse in kPa-ms or psi-ms based on unit_system.

• reflected_impulse: float, None

  Reflected impulse in kPa-ms or psi-ms based on unit_system.

• shock_front_velocity: float, None

  Shock front velocity in m/s or ft/s based on unit_system.

• all_units: dict

  Dictionary containing key: value pairs where the key is the attribute name as a str and the value is the unit as str.

Methods:

• to_dict()

  Returns a dict representation of the dataclass

• __repr__()

  Inherits the default dataclass behaviour

• __str__()

  "Pretty" representation of the data as str

Examples:

Example 1: Single Attribute

import kingery_bulmash as kb

res = kb.Blast_Parameters(unit_system=kb.Units.METRIC, 
                          neq=10000, 
                          distance=500, 
                          safe=True)

#getting only incident pressure
pr = res.incident_pressure

#getting the units of incident pressure
pr_u = res.all_units['incident_pressure']

print(pr, pr_u)

Expand to see console output

5.0549639655028455 kPa

Example 2: Loop Over Range (safe=False)

In this example we set safe=False as the range of scaled distances allowed by incident_impulse is larger than shock_front_velocity which would cause a ValueError sooner if safe=True. Try and except used to handle when distance is 0.

import kingery_bulmash as kb

NEQ = 5000
for dist in range(0, 10000, 1000):
    try:
        RES = kb.Blast_Parameters(unit_system=kb.Units.IMPERIAL,
                                  neq=NEQ,
                                  distance=dist,
                                  safe=False)
        
        i_imp = RES.incident_impulse
        i_imp_u = RES.all_units["incident_impulse"]
        
        print(f'{dist} ft: {i_imp} {i_imp_u}')
    
    except ValueError as err:
        print(f'{dist} ft: {err}')

Expand to see console output

0 ft: 'distance' must be > 0.
1000 ft: 26.167261959845302 psi-ms
2000 ft: 12.835212556333252 psi-ms
3000 ft: 8.344381432625331 psi-ms
4000 ft: 6.147651070542891 psi-ms
5000 ft: 4.8505476573514335 psi-ms
6000 ft: 3.99668842429768 psi-ms
7000 ft: None psi-ms
8000 ft: None psi-ms
9000 ft: None psi-ms

Build/Install/Test From Source

The build-system is Hatch.

To build and install from source, clone the repository and in the root folder run:

hatch build

To install with pip, also from the root folder, run:

pip install dist\kingery_bulmash-X.X.X-py3-none-any.whl

Adjust the file name/path accordingly.

To run tests:

hatch test